Sintering-induced aggregation of active metals is a major cause of catalyst deactivation. Catalysts that can operate above 800°C are rare. Here, we report an unusual noble metal catalyst with sintering-induced activation at temperatures up to 1,000°C. The catalyst consists of atomically dispersed palladium embedded in a reducible SnO2 support designated for lean methane combustion. High temperature reaction simultaneously causes favorable changes of palladium ensemble state combining synergistically with lattice oxygen activation. Such changes lead to at least one order of magnitude improvement of the intrinsic reactivity, which compensates the surface area loss. Extensive characterizations such as atom probe tomography, X-ray absorption spectroscopy, and isotope tracking together with theoretical calculations illustrate the structure and surface chemistry changes and their impacts on the reaction mechanism. The catalyst also shows notable long-term stability and facile regeneration after poisoning. Our work may provide new insights into designing active and thermally stable catalysts.
Organic photovoltaics (OPVs) have developed rapidly since the advent of fused-ring electron acceptors (FREAs). FREAs bearing bulky fused-ring cores, end-capped with electron-withdrawing groups, present advantages such as broad absorption, tunable frontier orbital levels, and good thermal stability. Recent breakthroughs demonstrate that FREA-based OPVs have achieved more than 17% efficiency, among which the end groups (EGs) of 1,1-dicyanomethylene-3-indanone (IC) and derivatives are critical for the performance enhancement. To date, more than 50 IC derivatives have been reported to construct high-performance FREA-based OPVs. In this review, we first introduce the chemical structure and synthesis route of the IC group. We discuss and classify the recent progress of FREAs based on IC and its derivatives, as well as the impact of IC on the morphology. We consider the issues the IC EGs face, including stability, isomerism, and EG redistribution, finally proposing some future directions for FREAs based on IC and its derivatives.
Chiral 1,3-propanediamine moieties are present in a range of bioactive small molecules, chiral catalysts, and ligands. The enantioselective desymmetrization of 2-substituted 1,3-propanediamines is a straightforward and efficient method to give access to these types of enantioenriched compounds. However, the state of the art of this strategy is limited to enzymatic catalysis and 2-monosubstituted substrates. Herein, we report the nonenzymatic desymmetrization of C-2-substituted 1,3-propanediamines through chiral phosphoric-acid-catalyzed asymmetric para-aminations of anilines with azodicarboxylates. Both C-2-monosubstituted and C-2-disubstituted 1,3-propanediamine substrates are compatible with this method, providing chiral 1,3-propanediamines bearing C-2 tertiary and quaternary stereocenters with high enantioselectivities. Preliminary mechanistic studies are performed to shed light on the reaction mechanism and the key asymmetric induction transition state.
Developing high-efficiency blue thermally activated delayed fluorescence (TADF) emitters is still a formidable challenge. Here, we report five blue TADF emitters designed by simply changing the frequently used methyl group (C1) to a longer one gradually to subtly adjust the energy levels. DAc-C1–DAc-C5 are developed by using diphenylsulfone (DPS) as the acceptor and acridine with different-length alkyl chains on C(9) as the donor groups. These five compounds have high photoluminescence quantum yields (PLQYs) (75%–84%) with blue emission. The DAc-C2-based OLED device exhibits the maximum external quantum efficiency (EQE) of up to 24.1% with CIE (0.15, 0.19), which is 1.42 times higher than that of state-of-the-art TADF OLEDs based on DAc-C1 (EQE: 17.0%) under the same conditions, confirming the power of the molecular design strategy. Furthermore, the crystal analyses partially explain the influence of the alkyl chain on the device property, demonstrating a new approach for achieving TADF luminogens with high performance.
Among several major unresolved challenges in reaction chemistry, controlling the yield and selectivity is particularly crucial. For on-surface synthesis (OSS), a prototype for basic understanding of reaction mechanisms, such control remains elusive. Here, using olefin cyclization, an important reaction in organic synthesis yet unknown for OSS to the best of our knowledge, as the model system, we propose a strategy to address this challenge by introducing carbon into the subsurface of Cu(111) (C-Cuδ+) and UV irradiation. The total olefin coupling rate on C-Cuδ+ increases to 10.1- and 5.3-fold higher than that on pristine Cu(111) at 298 and 323 K, respectively. The initial cyclization temperature reduces by 55 K on C-Cuδ+. UV irradiation further promotes the cyclization ratio from 22% to 40.3%. By integrating surface catalysis of the substrate with photochemistry of light-absorbing reactants, our results may open up a promising route for overcoming high reaction barriers and regulating selectivity in OSS.
Forming light-transmitting structures on c-Si photovoltaics to transmit visible light without wavelength dependency is a promising strategy to realize neutral-color transparent c-Si photovoltaics (c-Si TPVs). However, dry etching, which is used to form a light-transmitting structure on c-Si, inevitably causes nanoscale surface damages such as scallops and plasma-induced damage in c-Si. This aggravates carrier recombination, which decreases power conversion efficiency (PCE) of c-Si TPVs. Here, we propose an effective chemical treatment method for removing nanoscale surface damage from c-Si microholes. A large neutral-color c-Si TPV after the chemical treatment exhibits a high PCE of 14.5% at a transmittance of 20%. The chemical treatment also enables systematic control of the hole size (167 nm/s), and, thus, the transmittance is easily tuned from 10% to 70%. The proposed chemical treatment satisfies the three development factors of (1) high PCE, (2) opportunity for scale up, and (3) facile light transmittance tuning of c-Si TPVs.
State-of-the-art p-i-n-based 3D perovskite solar cells (PSCs) use nickel oxide (NiOX) as an efficient hole transport layer (HTL), achieving efficiencies >22%. However, translating this to phase-pure 2D perovskites has been unsuccessful. Here, we report 2D phase-pure Ruddlesden-Popper BA2MA3Pb4I13 perovskites with 17.3% efficiency enabled by doping the NiOX with Li. Our results show that progressively increasing the doping concentration transforms the photoresistor behavior to a typical diode curve, with an increase in the average efficiency from 2.53% to 16.03% with a high open-circuit voltage of 1.22 V. Analysis reveals that Li doping of NiOX significantly improves the morphology, crystallinity, and orientation of 2D perovskite films and also affords a superior band alignment, facilitating efficient charge extraction. Finally, we demonstrate that 2D PSCs with Li-doped NiOX exhibit excellent photostability, with T99 = 400 h at 1 sun and T90 of 100 h at 5 suns measured at relative humidity of 60% ± 5% without the need for external thermal management.
While splice modulators have entered clinical trials, limited clinical efficacy in splicing factor mutation-driven malignancies, such as acute myeloid leukemia, has remained a challenge. There is a pressing unmet medical need for developing potent small molecule splice modulators for the treatment of a broad array of malignancies characterized by splicing deregulation. However, the inability to practically access gram-scale lead molecules with viable pharmacological properties continues to hinder their application. Here, we report a scalable approach to prepare 17S-FD-895, a potent in vivo active splice modulator. The strategy described herein not only provides material to enable clinical translation but also furthers lead validation by expanding the structure-activity relationships that guide splice modulation.
The availability of MXenes and other two-dimensional conductive nanomaterials with tunable surface chemistry has reshaped the field of electromagnetic protection. However, the high electrical conductivity and low dielectric loss of titanium-based MXenes lead to strong reflection of electromagnetic waves, even when combined with polymers to form composites. Here, we report on the ability of vanadium-based MXenes to provide broadband microwave absorption. Polyurethane composites with ∼2 wt % Vn+1CnTx can absorb 90% of electromagnetic waves covering the entire X band. In addition, pure Vn+1CnTx films of submicrometer thickness can provide effective electromagnetic interference shielding. The free electron transport, surface terminations, native defects, and layers arrangement in composites have profound effects on electronic and dielectric properties of Vn+1CnTx MXenes. This study points toward a new frontier for development of thin and highly absorbing MXene-based electromagnetic protection materials.
Real-time diagnosis is required to ensure the safety, reliability, and durability of the polymer electrolyte membrane fuel cell (PEMFC) system. Two categories of methods are (1) intrusive, time consuming, or require alterations to the cell architecture but provide detailed information about the system or (2) rapid and benign but low-information-yielding. A strategy based on alternating current (AC) voltage response and one-dimensional (1D) convolutional neural network (CNN) is proposed as a methodology for detailed and rapid fuel cell diagnosis. AC voltage response signals contain within them the convoluted information that is also available via electrochemical impedance spectroscopy (EIS), such as capacitive, inductive, and diffusion processes, and direct use of time-domain signals can avoid time-frequency conversion. It also overcomes the disadvantage that EIS can only be measured under steady-state conditions. The utilization of multi-frequency excitation can make the proposed approach an ideal real-time diagnostic/characterization tool for fuel cells and other electrochemical power systems.
Extensive efforts are currently underway to develop safe and cost-effective electrolytes for large-scale energy storage. In this regard, water-based electrolytes may be an attractive option, but their narrow electrochemical stability window hinders their realization. Although highly concentrated fluorinated electrolytes have been shown to be highly effective in suppression of water splitting, enabling significant widening of the applied potential range, they utilize expensive salts (e.g., lithium bis(trifluoromethane sulfonyl) imide [LiTFSI] or lithium trifluoromethane sulfonate [LiOTf]); hence, they cannot be considered for practical applications. Here, we demonstrate a cost-effective aqueous electrolyte solution combining 14 M LiCl and 4 M CsCl that allows stable operation of a 2.15-V battery comprising a TiO2 anode and LiMn2O4 cathode. Addition of CsCl to the electrolyte plays a double role in system stabilization: the added chloride anions interact with the free water molecules, whereas the chaotropic cesium cations adsorb at the electrified interface, preventing hydrogen formation.
Supramolecular chemistry has gone from strength to strength in recent decades, with its impact felt from catalysis to materials science to chemical biology. This Voices article, published to coincide with the 2022 Macrocyclic and Supramolecular Chemistry Group meeting at the University of Nottingham, UK, asks speakers from the meeting: what are the major challenges and opportunities facing the field in coming years?
Expanding decarbonization efforts beyond the power sector are contingent on cost-effective production of energy carriers, like H2, with near-zero life-cycle carbon emissions. Here, we assess the levelized cost of continuous H2 supply (95% availability) at industrial-scale quantities (∼100 tonnes/day) in 2030 from integrating commodity technologies for solar photovoltaics, electrolysis, and energy storage. Our approach relies on modeling the least-cost plant design and operation that optimize component sizes while adhering to hourly solar availability, production requirements, and component inter-temporal operating constraints. We apply the model to study H2 production costs spanning the continental United States and, through extensive sensitivity analysis, explore system configurations that can achieve $2.5/kg levelized costs or less for a range of plausible 2030 technology projections at high-irradiance locations. Notably, we identify potential sites and system configurations where PV-electrolytic H2 could substitute natural gas-derived H2 at avoided CO2 costs (≤$120/ton), similar to the cost of deploying carbon capture and sequestration.
Doped polysilicon-based passivating contacts are expected to be a key technology to enable higher efficiency in mass-produced silicon solar cells in coming years, with the world market share expected to increase almost 9-fold to 35% in 2031. The excellent carrier selectivity of passivated contacts enables low-resistance extraction of carriers without compromising surface passivation and has been instrumental in recent advances in high-efficiency solar cells. Here, we report on the application of phosphorus-doped polysilicon passivating contacts on large-area screen-printed n-type silicon solar cells, using industrially viable fabrication processes. A champion cell efficiency of 24.79% is reported, as independently measured by ISFH-CalTeC on a 163.75 × 163.75-mm solar cell. Detailed characterization and simulation are applied to investigate the primary losses and pathways for further improvement of the state-of-the-art industrial high-efficiency solar cell, revealing that the front-side boron-diffused region accounts for around 63% of the electrical losses.
III–V/Si epitaxial tandems with a 1.7-eV GaAsP top cell promise stable power conversion efficiencies above the fundamental limit of Si single-junction cells. However, III–V/Si epitaxial tandems have suffered from limited minority carrier diffusion length in the top cell, leading to reduced short-circuit current densities (JSC) and efficiencies. While conventional wisdom dictates that dislocation density in III–V/Si tandems must be reduced to boost efficiency, here, we show that heterointerface design and growth sequence also play critical roles in reducing recombination losses. Our improved GaAsP cells make use of a wide-band gap AlGaAsP electron-blocking layer that forms a pristine interface with GaAsP, resulting in a 10%–20% (absolute) boost in quantum efficiency over previous work in the critical red wavelength range (600–725 nm), despite similar dislocation density. Combining the improved top cell carrier collection with Si backside texturing, we obtain 25.0% efficient GaAsP/Si tandem cells with a closely matched JSC of 18.8 mA/cm².
Discovering new inorganic photovoltaic materials becomes an efficient way for developing a new generation of solar cells with high efficiency and environmental stability. Using machine learning (ML) and density functional theory calculations, we report four promising inorganic photovoltaic materials—Ba4Te12Ge4, Ba8P8Ge4, Sr8P8Sn4, and Y4Te4Se2—demonstrating notable theoretical photovoltaic performance for use in solar cells. The symmetry-allowed optical transition probability, the large amount of density of states near the conduction band minimum (CBM) and the valence band maximum (VBM), and the strong p-p transition across the band edge contribute to the large optical absorption coefficient, leading to the outstanding theoretical power conversion efficiency (PCE). The separation of the VBM and CBM wave function distributions contribute to the fast separation of the photogenerated electrons and holes and the enhanced carrier lifetimes. Our ML model is an efficient method for fast and atomic-level accuracy prediction of photovoltaic materials with different crystal structures.
Two-dimensional (2D) π-conjugated polymers are promising electronic materials with diverse properties controlled by varying the structure of organic building blocks. We here report an organic framework with perchlorotriphenylmethyl (PTM) radical nodes, synthesized through dehalogenative thermolysis polymerization of tris(iodotetrachlorophenyl)methane. The resulting C-C-linked P²PTM is characterized by X-ray photoelectron, NMR, Raman, and FTIR spectroscopies and X-ray diffraction. Exfoliated, layered 2D sheets can be imaged with TEM and AFM. N2 adsorption experiment indicates a permanent porosity with a surface area of 150 m²/g, and dynamic vapor sorption shows a specific adsorption of one chloroform molecule per P²PTM unit cell, in line with modeling. DFT calculations predict degenerate Mott-insulating antiferromagnetic and ferromagnetic states, while the semi-metallic closed-shell configuration is less stable by ∼1 eV. Experimentally, P²PTM is a low-bandgap black solid with moderate electrical conductivity (∼4 × 10⁻⁴ S cm⁻¹), gate-modulated ambipolar charge transport and paramagnetic behavior down to 1.9 K.
The atomistic design of positive electrode materials requires understanding of (1) how guest cations diffuse through an intercalation host to fill empty interstices and (2) the distortions of the host lattice induced as a result of ion intercalation. Here, we report the use of topochemistry to access single-crystals of a metastable 2D van der Waals solid, γʹ-V2O5, and examine its single-crystal-to-single-crystal transformations upon lithiation up to γ-LiV2O5. High-resolution single-crystal diffraction provides an atomistic view of preferred interstitial sites occupied by Li ions and distortions of the 2D lattice in an extended solid-solution lithiation regime, which stands in stark contrast to the thermodynamic α-V2O5 phase. These results illustrate the potential of metastable compounds with reconfigured atomic connectivity to unlock lithiation pathways and mechanisms that are profoundly different from their thermodynamic counterparts. The study furthermore demonstrates the viability of combining topochemical modification with single-crystal diffraction to image intercalation phenomena with atomic resolution.
Well-defined aerosols pave the way for versatile basic and applied research. Here, we demonstrate a unique whipping instability that generates from a high-aspect-ratio microfluidic device resulting in a unique steady-state gas-focused whipping jet (WJ) without any need for electrification. This WJ device emanates a multi-monodisperse whipping spray jet with a two-dimensional (2D) profile. We demonstrate this phenomenon based on various fluidic parameters theoretically and experimentally. The 2D WJ’s unique behavior is derived using analytical fluid dynamics to explain jet diameter, whipping regime, and spreading angle. The phenomenon is further characterized experimentally by measuring the angle with respect to the flow rate, the distances between droplets, the droplet shapes, and the reproducibility of these parameters. We also explain the precise fabrication of such inexpensive devices. Lastly, we highlight these devices’ potential use as sample environments in versatile applications ranging from cryoelectron microscopy over mass spectrometry to drug formulation and structural studies at X-ray free-electron lasers.
To date, MXene dispersions have been mostly limited to polar solvents. Here, we show that when the lithium cations present between MXene multilayers after etching are exchanged with di(hydrogenated tallow)benzyl methyl ammonium chloride (DHT), they become organophilic and form highly stable colloidal suspensions in nonpolar solvents. The rapid cation exchange occurs under ambient conditions and the resulting two-dimensional flakes are well dispersed and remain oxide free. A 142 ± 0.7-μm thick film (≈10 mg ⋅ cm⁻²) made from a DHT-Ti3C2Tz suspension in toluene exhibits pseudocapacitive behavior, with a capacitance of 305 F ⋅ g⁻¹ at a scan rate 2 mV ⋅ s⁻¹. The moduli and tensile strengths of solution-processed polyethylene nanocomposites are increased by ≈11% and 32% with a loading of ≈1 vol% DHT-Ti3C2Tz. Our approach may enable the use of MXenes in multiple research and industrial fields.
Quasi-two-dimensional (2D) organic-inorganic hybrid tin perovskites have emerged as promising alternatives to lead-based perovskites in thin-film photovoltaics because of their reduced toxicity and improved stability. However, the undesired small n-value 2D phases and disordered crystal orientation enormously restrict the efficiency of quasi-2D tin perovskite solar cells (PSCs) due to uncontrollable nucleation and crystal growth processes. Here, we propose a mixed pseudo-halide anion engineering approach by using acetate (Ac⁻) and tetrafluoroborate (BF4⁻) anions to make quasi-2D Ruddlesden-Popper perovskites with a target formula of PEA2FA4Sn5I16. We find that the mixed Ac⁻ and BF4⁻ anions can not only promote homogeneously distributed PEA⁺ cations in the precursor by effectively breaking the PEA⁺···PEA⁺ stacking but also retard the crystallization process by coordinating with unbonded SnI2, thereby, significantly reducing small n-value 2D phases, improving the crystal orientation, and suppressing the Sn²⁺ oxidation. The resulting PSC exhibits up to 9% power conversion efficiency and 400 h stability.
The unique properties of two-dimensional (2D) materials have boosted intensive interests in combining distinct 2D materials into van der Waals heterojunctions for novel device structures. The organic-inorganic heterojunctions, integrating atomically thin inorganic materials with an unlimited variety of organic molecules, provide an ideal platform for broader, superior, and on-demand functional applications by incorporating customized organic molecules that particularly exhibit decent optoelectronic properties, promising scalability and remarkable flexibility. In this Review, emerging 2D organic-inorganic heterojunctions from the perspectives of materials, manufacturing, structures, and interfaces, as well as recent progress in functional applications, are provided. Two prototypical construction approaches are summarized—epitaxy growth and molecular doping—followed by four directions of device applications, including electronic device, optoelectronic device, energy harvesting device, and memory and neuromorphic device. Finally, the frontier challenges and future outlook associated with the organic-inorganic heterojunctions are highlighted, which is critical for the further development of this cross-fertilized research field.
Roll-to-roll (R2R) fabrication of flexible and transparent all-solid-state supercapacitors (FT-ASSCs) is extremely challenging because of the classic trade-off between transparency and capacitance. In this work, we develop fully three-dimensional (3D)-printed, sandwich-type FT-ASSCs comprised of 3D line-patterned carbon black (CB)/Ag/CB electrodes on a transparent dialysis membrane (DM) separator. By tailoring the line pitch of the 3D electrodes, our FT-ASSC is able to achieve more than 80% optical transmittance and significantly higher areal capacitance than an opaque ASSC. More importantly, the performance of 3D-printed FT-ASSCs is unrestricted by the transparency-capacitance trade-off, and they exhibit a superior capacitive figure of merit value compared with state-of-the-art FT-ASSCs reported in the literature. Additionally, our FT-ASSCs demonstrate excellent cyclic stability and mechanical robustness because of the chemical and mechanical stability of the DM separator and effective encapsulation of polyurethane. The single-flow 3D printing technique introduced here can meet the requirements for industrial-scale R2R manufacturing of energy storage devices.
Organizing colloidal particles into 3D superstructures is a promising strategy for fabricating functional metamaterials with novel optical, electric, and catalytic properties. The rich surface properties of colloidal particles provide many ways to manipulate their assembly behavior. Emulsion droplets are ideal microspaces for confining colloidal self-assembly, offering many advantages such as versatility, scalability, and controllability over size, shape, and composition. In this review, we first introduce recently developed strategies for the emulsion-confined assembly of colloidal particles into 3D superstructures by manipulating the interfacial properties of the emulsion droplets and colloidal particles, then demonstrate the novel collective properties of the assembled superstructures and highlight some of their unique optical and catalytic properties andapplications in bioimaging, diagnosis, drug delivery, and therapy.
Light-based 3D bioprinting is an emerging technology to engineer cellular constructs toward functional tissues. However, there is still an urgent need for materials with high printing resolution and allow cell-laden printing. Here, we report a biomacromolecule additive, which can efficiently improve the photocuring resolution of commonly used bioinks, mainly by inhibiting the free radical polymerization at unexposed areas during patterned photoinitiation. Fine structures can be manufactured by digital light processing (DLP) 3D printing and the resolution can reach a 10 μm level. Besides, CSNB can increase the mechanical property of amino-containing materials. CSNB reduces cytotoxicity by avoiding the burst release of photoabsorbers and shows good biocompatibility. GelMA/CSNB bioink was used to print multicell-laden hydrogels with complex patterns and supported the proliferation of encapsulated cells. CSNB thus represents a biocompatible bioink additive that provides an easy approach to improving printing resolution and supports cell-laden printing with multiple cell types.
Opening the graphene zero bandgap and simultaneously keeping its linear electronic dispersion has been widely accepted as a very challenging scientific puzzle. Moreover, one of the biggest obstacles for all-perovskite tandem solar cells is the lack of perovskite semiconductors with a narrow bandgap (<1.2 eV). Here we examine these two issues and theoretically identify the environmentally friendly perovskite A2HfTe4 (A = Ca, Sr, Ba), especially Ba2HfTe4. This material is a good candidate for three-dimensional graphene-like semiconductors with two-dimensional electronic dimensionality, linear band-edge dispersion, a direct bandgap of 0.77–0.96 eV, carrier effective mass and mobility similar to graphene, visible-light absorption beyond Pb-based perovskites, and power conversion efficiency approaching ∼28%. A2HfTe4 is a promising bottom-cell material that helps achieve all-perovskite tandem solar cells thanks to its narrow bandgap and acts as a potential alternative to the currently popular perovskite-silicon tandem solar cells.
Abundant sodium resources provide compelling competitive advantage for sodium-ion battery (SIBs) applications. Correspondingly, it is urgently required to develop high-performance and low-cost anode materials for SIBs. Here, we report a composite of antimony nanoparticles anchored on N/S co-doped 3D carbon for superior SIB anodes. During the synthesis, NaCl exerts a “pinning effect” to restrict the growth of antimony in the carbon matrix and results in nano-sized antimony particles. Given the enhanced-charge/ion-transfer kinetics ensured by nano-Sb and the structural advantages derived from the N/S co-doped 3D porous carbon, which not only remain robust upon cycling but also undergo graphitization by the ion shuttle effect to stimulate a stronger electrochemical response during the activation process, this composite maintains a 98.9% capacity ratio over 20,000 cycles at 10 A g⁻¹. Furthermore, molecular dynamics simulations reveal that the degree of graphitization has a linear relationship with the ionic radius.
The realization of actuators that can output thrust is critical for improving the comprehensiveness of actuator functions and broadening the range of soft robot applications. Thrust actuation can be achieved by the volume expansion of active materials under the stimulus, but most expandable materials suffer from the low rate of volume change and/or uncontrollable expansion directions. Here, we design a 3D network of carbon nanotubes with gradient stiffness. By synergistically utilizing the different responses of each stiffness layer to solvent stimuli, a solvent-responsive actuator that can deform rapidly and output thrust directionally is prepared. By adjusting the parameters of the actuator, it can achieve a variety of complex actuations such as multidirectional actuation, multifunctional actuation, sequential actuation, and programmable actuation.
Additively manufactured (AM) three-dimensional (3D) mesostructures exhibit geometrically optimal mechanical, thermal, and optical properties that could drive future microrobotics, energy harvesting, and biosensing technologies at the micrometer to millimeter scale. We present a strategy for transforming AM mesostructures into 3D electronics by growing nanoscale conducting films on 3D-printed polymers. This highly generalizable method utilizes precision atomic layer deposition (ALD) of conducting metal oxides on ultrasmooth photopolymer lattices printed by high-resolution microstereolithography. We demonstrate control of 3D electronic transport by tuning conformal growth of ultrathin amorphous and crystalline conducting metal oxides. To understand the scaling of 3D electrical properties, we apply graph theory to compute network resistance and precisely design the 3D mesostructures' conductivity. Finally, we demonstrate 3D-enhanced multimodal sensing of chemical, thermal, and mechanical stimuli, geometrically boosting sensitivity by 100× over 2D films and enabling a new class of low-power, 3D-printable sensors.
Predicting metal-binding sites in proteins is critical for understanding the protein’s biological function. Here, we develop an ensemble deep convolutional neural network (CNN) method for predicting metal-binding sites based on their three-dimensional (3D) structure. We build multi-channel 3D voxels based on biophysical characteristics obtained from raw atom coordinates of each protein-binding pocket. Then, we use these 3D voxels as the input of an ensemble 3D CNN model. We train and evaluate the model using a curated dataset of 3D protein structures. Our proposed model shows high performance in predicting metal-binding sites for Zn, Fe, Mg, Mn, Ca, and Na. Our approach offers a framework to use 3D spatial features to train 3D-CNN, which may be used to predict complicated metal-binding sites directly from their biophysical characteristics. The source code and webserver of the model are publicly available.
Acute myocardial infarction (AMI) is one of the highest mortality diseases in the world. It is critical to treat AMI patients within a few hours, which can explain the high mortality. However, timely diagnosis of AMI out of hospital is still challenging because of low accuracy, sophisticated testing procedures, and requirement of experienced professionals. Here, we propose ultra-sensitive, facile, and rapid detection of the AMI biomarker by using a three-dimensional affinity biosensor (3DA-biosensor), which uses a graphene field-effect transistor constructed with a superwetting hydrogel-aptamer hybrid layer. The 3DA-biosensor exhibits the high sensitivity, adjustable sensitive range, and self-filtration ability, evidenced by a limit of detection down to 1.08 × 10⁻⁹ nM in whole blood. Through preliminary application tests, the 3DA-biosensor enables the identification of positive or negative for patient samples within 5 min, with the accuracy rate over 94%, paving a way for convenient self-screening of AMI for the patients with suspected symptoms.
Development of efficient and stable electrodes for hydrogen and oxygen evolution from water constituted of abundant elements and prepared by sustainable and scalable procedures is of considerable importance for producing green hydrogen from renewable electricity. Herein, a method for the preparation of Ni2P, Fe2P, and FeP supported on N-doped graphene (NiP/NG and FeP/NG) is reported. The procedure uses metal salts, phosphorous oxide, and chitosan as precursors of metal phosphide and N-doped graphene, avoiding the use of undesirable and hazardous precursors, such as PH3 or NaH2PO2, and rendering a material with a strong metal phosphide-graphene interaction. Moreover, NiP/NG and FeP/NG electrodes are demonstrated to be more efficient than the benchmark catalysts Pt/C and RuO2, for hydrogen evolution reaction and oxygen evolution reaction, respectively, at a large current density (300 mA/cm²). In addition, water electrolysis was carried out using NiP/NG//FeP/NG electrodes, also demonstrating improved efficiency and stability compared with Pt/C//RuO2 at a current density (400 mA/cm²) near industrial requirements.
Solid-state lithium-metal batteries possess intrinsic advantages in terms of both safety and energy density. However, the fundamental origin of electrochemical lithium deposition heterogeneity in solid-state batteries is much less understood than that in lithium-metal batteries using a liquid electrolyte, partly due to the difficulties of directly mapping lithium-deposition reaction fronts and the associated changes in local stress of the solid-state electrolyte. Here, we trace the evolution of three-dimensional microscopic stress and demonstrate that the stress distribution is rather broad in a garnet solid-state electrolyte during processing and battery cycling using confocal Raman spectroscopy. We further discuss the effect of local stress variations on the overpotential of lithium deposition as the most likely origin of lithium-deposition heterogeneity in garnet systems. The ex situ stress-mapping tool developed in this work provides a strong basis for understanding the electromechanical effects, a prerequisite to fully unlock the potential of solid-state lithium-metal batteries.
Maintaining a high working frequency is one of the critical technical solutions to the triboelectric nanogenerator (TENG) for improving its output power. Herein, we propose a bearing structural TENG (BS-TENG), which achieves a speed of nearly 1,500 rpm based on the diversified design of 3D printing. It is vital that a BS-TENG unit delivers a peak power of 0.96 mW under an external load of 8 MΩ and, in addition, charges a capacitor of 1,000 μF to reach a voltage of 4 V that takes merely 80 s at a rotational speed of 600 rpm. The integrated BS-TENG network serves as both an energy harvester and a self-powered high-speed sensing system for the safe operation of vehicles. This study presents an approach for upgrading the working frequency of TENGs and may provide new opportunities for TENGs in intelligent automobile driving systems.
The regulation of fluorescence color and wavelength of organic luminescent materials is important for their practical applications. However, the aggregation-caused quenching (ACQ) effect in the aggregate state, complex synthesis, sophisticated regulations, and abrupt color transitions of most materials have made such a mission challenging. Here, we develop a color-tunable solid-emitters system based on mechanochromic aggregation-induced emission luminogens (AIEgens). By changing the molecular structure and molecular packing of AIEgens, the wavelength and color of emissions can be adjusted smoothly and easily across the entire visible spectrum. In addition to their reversible, tunable, and highly efficient fluorescence, these AIEgens have the advantage of being difficult to quantify and imitate because of their force response. Taking advantage of these excellent performances, we develop three applications based on the advanced solid optical materials: (1) 4D code, (2) anti-counterfeiting patterns, and (3) full-color light-emitting diodes.
While lithium-oxygen batteries exhibit high theoretical energy densities that by far exceed those of conventional lithium-ion batteries, there are a limited number of examples that actually demonstrate cells with high energy density. The limitation of the positive electrode with a capacity high enough to sustain repeated discharge/charge cycles under high areal capacity conditions hinders the implementation of the lithium-oxygen batteries with practically high energy density. In this study, we develop a carbon black powder-based self-standing membrane, which exhibits a discharge capacity of ~7,000 mAh/gelectrode even under high current density conditions (>0.4 mA/cm²). Using the developed self-standing carbon membrane as the positive electrode, a 500-Wh/kg class rechargeable lithium-oxygen battery was fabricated and a repeated discharge/charge cycle was demonstrated at 0.1 C-rate. The results obtained in this study provide new material research directions to realize high energy density rechargeable lithium-oxygen batteries and facilitate their future development.
Engineering icephobic surfaces has been a long-standing effort to address the challenges of ice prevention and removal in our daily life and industrial applications. Superhydrophobic surfaces and photothermal effect have shown their distinct merits in anti-icing and deicing. It is highly desirable to exploit their mutual benefits to realize passive, durable, and sustainable icephobicity even at extremely low temperatures. We report on a superhydrophobic selective surface constructed with a hierarchical architecture to enable stable superhydrophobicity and high-efficiency solar-thermal conversion. The surface spectral selectivity is deliberately designed to maximize solar harvesting while minimizing the thermal re-radiation loss. The boosted solar-thermal conversion empowers remarkable anti-icing of a sessile droplet at a record-low temperature of −60°C under 1-sun illumination. The synergy of solar-thermal conversion and superhydrophobicity endows the surface with superior and durable icephobicity. Moreover, the presented icephobic surface shows great potential and broad impacts, owing to its all-solution-based scalable fabrication method.
Owing to multiple-electron transfer of producing CH4 from photocatalytic CO2 reduction (CO2PR), a great challenge is achieving high selectivity of CH4, especially under long-wavelength irradiation. Herein, we synthesize a series of monolayer Ni3X-layered double hydroxide (LDH) (m-Ni3X-LDH, X = Cr, Mn, Fe, Co). When applied for CO2PR, the selectivity of CH4 exhibits a volcano-like trend with the highest point at m-Ni3Mn-LDH using Ru-complex as the photosensitizer. After further optimization, nearly 99% selectivity of CH4 is achieved under irradiation with λ = 600 nm. Accordingly, structural characterizations prove the presence of metal and hydroxyl defect sites, in which the surface valence states of Ni and O exhibit a volcano-like trend with the lowest point at m-Ni3Mn-LDH. Thus, the high selectivity of CH4 could be attributed to the efficient electron-hole migration and separation in m-Ni3Mn-LDH. Moreover, the electron-rich Ni-O bond in m-Ni3Mn-LDH may act as the adsorption site for CO∗, promoting the further hydrogenation of CO to CH4 and improving the selectivity of CH4.
The low-temperature direct ammonia fuel cell (DAFC) is an attractive option for zero-emission transportation. However, the demonstration of high-performance and durable DAFCs and the identification of their suitable market are not yet reported. Here, we show a high-performance DAFC enabled by a hydrophobic spinel cathode, which achieves peak power density of 410 mW cm⁻² and continuous operation for 80 h at 300 mA cm⁻². We assemble five 50 cm² cells into a 75 W DAFC stack, showing a comparable area-specific performance to that of the single cell. The best combination of performance and durability for the single cell and, particularly, the demonstration of, to the best of our knowledge, the world’s first DAFC bipolar stack constitute a significant development of DAFC technology. We also perform an in-depth techno-economic analysis of a 2 kW, 10 kWh DAFC system serving for drones. DAFC systems with the performance obtained herein could be a competitive power source alongside hydrogen fuel cells and Li-ion batteries.
Electrokinetic energy conversion by streaming current was proposed for energy harvesting for >50 years; however, it proved to be of limited use due to low efficiencies. The recent emergence of nanomaterials and related technologies significantly increased these efficiencies. Here, we report an electrokinetic energy conversion system using a single stream of ballistic droplets from which we obtain close to 80% efficiency with 25 kV generated voltage. The voltage can be reduced to a minimum of 4 kV while maintaining ∼40% efficiency, a promising feature from the point of view of applications. Furthermore, we investigate the possibility of integration with 9 microjets as a conversion unit, which generates 1.9 mW with an efficiency of 35%. We experimentally achieve a power density of 8.4 kW/m² under 0.4 bar pressure and an upper limit of 84 kW/m² using denser pore arrays. Our results demonstrate efficient ballistic energy conversion, as well as the potential for integrated applications.
Flexible electronics have been rapidly developed in recent years. However, there are still some concerns about the degradation and short life caused by mechanical damage during their operation. Here, we present a self-healing electret nanogenerator (SENG) that can restore its structure and function after mechanical damage, benefiting from a healable polymer with reversible imine bond and the instantaneous healing ability of liquid metal. After destructive testing comprising four cutting-healing cycles the output current of the SENG autonomously recovers to the original values before damage. Finally, as a practical device, the SENG is demonstrated to work in both energy harvesting and human physiology-monitoring applications. This research offers a feasible route for improving reliability and lifetime of electret generators or other flexible electronics that suffer from mechanical damage.
Latent Mycobacterium tuberculosis (Mtb) shielded in macrophages is hard to detect and eradicate, causing lethal respiratory failure and systemic inflammation. Here, we synthesize an aggregation-induced emission luminogen (AIEgen) with metabolic labeling and in situ photodynamic scavenging functions via click chemistry. By participating in cytoderm peptidoglycan biosynthesis, the wash-free AIEgen presents quick (10 min) and selective metabolic labeling to live Mtb and obtains 50-fold better detection sensitivity of tuberculosis compared with acid-fast bacilli (AFBs). Notably, the AIEgen demonstrates accurate (>96%), sensitive (>96%), and specific (100%) clinical tuberculosis diagnosis using bronchoalveolar lavage fluid (BALF) and sputum samples. Upon low-power light irradiation, the AIEgen generates lethal-dose reactive oxygen species (ROS) to break the bacterial cytoderm and significantly improves the sensitivity of Mtb to rifampicin via photodynamic ablation. The AIEgen is a clinically oriented diagnostic for tuberculosis mass screening in regions with low income and a high tuberculosis burden and shows excellent potential for photodynamic ablation of drug-resistant tuberculosis.