City University of Hong Kong

Designing efficient and stable electrocatalysts for the hydrogen and oxygen evolution reactions (HER and OER) is crucial for green hydrogen production via the water‐splitting system. The bifunctional electrocatalyst offers a promising strategy due to the simplified preparation process and reduced expenses. However, the single‐component bifunctional catalysts often struggle to match the redox potential of water and to achieve proper adsorption/desorption of Gibbs free energy for both hydrogen and oxygen intermediates simultaneously. Herein, through precisely controlling the topological transformation path of the RuNiOx precursor, we successfully prepared high‐performance RuNi/Ni and Ru/NiO heterostructure electrocatalysts for the HER and OER, respectively. The energy level matching between the fabricated electrocatalyst and water oxidation/reduction potential confirms the feasibility of HER and OER. The synergistic effect between the active sites ensures rapid intermediate adsorption/desorption kinetics. As a result, the assembled alkaline overall water splitting setup achieves a current density of 1 A cm⁻² at 2 V and maintains stable operation at 100 mA cm⁻² for 100 hours.

Metallic materials serving as indispensable conductors critically influence the performance of flexible electronics. Conventional structural designs have restricted metallic materials to exhibiting pure elastic deformation, but recent developments have emphasized an increased significance of plastic deformation, showing great potential for new breakthroughs in developing novel flexible electronics. This review first introduces the elastoplastic behavior of metallic materials, especially those capable of withstanding remarkable plastic deformation. The main design strategies toward flexible and stretchable electronics expanding elastic deformation range are then summarized, incorporating both strain alleviation and strain delocalization. Innovative studies exploiting plasticity for enhancing device performances or achieving shape‐forming and reconfigurable electronics are further highlighted. Some perspectives on utilizing the elastoplastic behavior of metallic materials to innovate the next generation of flexible electronics are finally provided.

Integrating semitransparent organic photovoltaics (ST‐OPVs) into building structures is a promising technology that serves aesthetic purposes while retaining window functionality, and it also facilitates solar energy harvesting and heat insulation. However, balancing power conversion efficiency (PCE), visible light transmittance (VLT), infrared radiation rejection (IRR), and color rendering index (CRI) for window applications remains a significant challenge. In this study, ST‐OPVs are developed that feature innovative near‐infrared‐absorbing materials. These devices are further coupled with an optical layer optimized through high‐throughput optical modeling to fine‐tune and enhance the different properties of the ST‐OPVs. Specifically, ST‐OPVs are achieved with a VLT of over 30%, a PCE of 12.5%, an IRR of over 90%, and a CRI of over 80. Furthermore, higher PCE of over 14% and IRR of over 95% can also be achieved, demonstrating the tunability of these photovoltaic properties. These figures highlight the exceptional performance of specialized ST‐OPVs for window applications, demonstrating their dual function of generating electricity and energy saving. Additionally, simulations show that replacing traditional heat insulation films with the ST‐OPVs can reduce annual energy demand by up to 60%, using Hong Kong as an example, underscoring their significant potential in sustainable building‐integrated photovoltaic (BIPV) applications.

The COVID-19 pandemic transformed homes into multifunctional spaces, highlighting their readiness to serve as informal workplaces and impacting the health of their inhabitants. Therefore, this study explores how architectural attributes influence self-perceived physical, mental, and social health and examines the mediated relationships among these health dimensions while working from home. Using survey data from 261 participants, we employed multiple regression and Partial Least Square Structural Equation Modeling (PLS-SEM) analyses to address two key questions: Which combination of health dimensions best explains the work-from-home situation? What housing attributes directly and indirectly foster physical, mental, and social health? Our findings showed the full mediation and sequential precedence of mental health prior to physical and social health in the work-from-home situation, offering the most robust model for linking built environment features to health dimensions. The implications for architectural design and the importance of creating health-supportive environments, primarily through improving indoor environmental quality and sociospatial features, are elaborated in the discussion, providing a detailed analysis of how different features impact health.

Wireless Power Transfer (WPT) technology, which can charge IoT devices over the air, has become a promising technology for IoT networks. In wireless-powered IoT networks, broadcasting is a fundamental networking service for disseminating messages to the whole network. To seek a fast and collision-free broadcast schedule, the problem of Minimum Latency Broadcast Scheduling (MLBS) has been well studied when nodes are energy-abundant. However, in wireless-powered networks, a node can only receive or transmit packets after it has harvested enough energy. In such networks, it is of great importance to exploit the divergent harvested energy to reduce the broadcast latency. Unfortunately, existing works always assume a predetermined tree and a fixed transmission power for broadcast scheduling, which greatly limits their performance. Thus, in this paper, we investigate the first work for the MLBS problem in wireless-powered networks without relying on predetermined trees. Firstly, the problem is formulated and proved to be NP-hard. Then, two structure-adaptive scheduling algorithms are proposed with a theoretical bound, which can intertwine the construction of broadcast tree with the computation of an energy-aware schedule simultaneously. Furthermore, a power-aware scheduling method is also proposed to take the structure of the broadcast tree, the adjustment of nodes’ transmission powers, and the interference during transmissions into account simultaneously. Additionally, the algorithm for the MLBS problem under the physical interference model is also studied. Finally, the theoretical analysis and simulation results verify that the proposed algorithms have high performance in terms of latency.

In this study, we investigate the effect of firm's business strategy on an important feature of chief executive officer (CEO) incentive compensation – the pay duration. Drawing on archival data collected from a large sample of US listed firms, we find that firms following a prospector strategy grant longer‐duration compensation to their CEOs than firms following a defender strategy. We further show that this effect of business strategy on pay duration is more pronounced for firms with higher information asymmetry and firms managed by CEOs with higher revealed ability. Our results are robust to alternative business strategy measures, an entropy balancing approach, alternative fixed‐effects models and an alternative pay duration measure that excludes performance‐vesting grants. Overall, the findings are consistent with prospector firms using longer pay duration to extend managers' investment horizon and to retain managerial talent.

Ionogel polymer electrolyte (IPE), incorporating ionic liquid (IL) within a polymer matrix, presents a promising avenue for safe solid‐state lithium metal batteries. However, sluggish Li+ kinetics, resulting from the formation of [Li(anion)n]‐(n‐1) clusters and the occupation of Li+ transport sites by organic cations, limit their practical applications. In this study, we have developed zwitterionic bottlebrush polymers‐based IPE with promoted Li+ conduction by employing poly(sulfobetaine methacrylate)‐grafted poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) (PVC‐g‐PSBMA) bottlebrushes as matrices of IL. The grafted zwitterionic side chains greatly facilitate the dissociation of [Li(anion)n]‐(n‐1) clusters to produce more movable Li+. Moreover, the positively charged −NR4+ groups in zwitterionic side chains effectively restrain anions migration, while the negatively charged −SO3− groups immobilize IL cations, preventing them from occupying Li+ hopping sites and reducing the energy barrier for Li+ migration. These synergistic effects contribute to a notable ionic conductivity (7.5×10−4 S cm−1) and lithium transference number (0.63) of PVC‐g‐PSBMA IPE at 25 oC. As a result, PVC‐g‐PSBMA IPE enables ultralong‐term (over 6500 h) reversible and stable Li plating/stripping in Li||Li symmetric cells. Remarkably, the assembled Li||LiFePO4 full batteries demonstrate unprecedented cycling stability of more than 2000 cycles with a superior capacity retention of 93.7%.

In recent years, self‐assembled monolayers (SAMs) anchored on metal oxides (MO) have greatly boosted the performance of inverted (p‐i‐n) perovskite solar cells (PVSCs) by serving as hole‐selective contacts due to their distinct advantages in transparency, hole‐selectivity, passivation, cost‐effectiveness, and processing efficiency. While the intrinsic monolayer nature of SAMs provides unique advantages, it also makes them highly sensitive to external pressure, posing a significant challenge for long‐term device stability. At present, the stability issue of SAM‐based PVSCs is gradually attracting attention. In this minireview, we discuss the fundamental stability issues arising from the structural characteristics, operating mechanisms, and roles of SAMs, and highlight representative works on improving their stability. We identify the buried interface stability concerns in three key aspects: 1) SAM/MO interface, 2) SAM inner layer, and 3) SAM/perovskite interface, corresponding to the anchoring group, linker group, and terminal group in the SAMs, respectively. Finally, we have proposed potential strategies for achieving excellent stability in SAM‐based buried interfaces, particularly for large‐scale and flexible applications. We believe this review will deepen understanding of the relationship between SAM structure and their device performance, thereby facilitating the design of novel SAMs and advancing their eventual commercialization in high‐efficiency and stable inverted PVSCs.

Photodynamic therapy (PDT) is attracting widespread attention as a promising strategy for tumor treatment. However, the efficacy of PDT is severely limited by the insufficient tissue penetration depth of the light source and low reactive oxygen species (ROS) generation efficiency. Herein, the metal doping strategy is reported to construct a series of defect‐rich M‐doped amorphous CoMo‐layered double hydroxide (a‐M‐CoMo‐LDH, M = Mn, Cu, Al, Ni, Mg, Zn) photosensitizers (PSs) for NIR‐II PDT. Especially, M‐doped CoMo‐LDH nanosheets are synthesized through a simple hydrothermal method and then etched by acid treatment to prepare defect‐rich a‐M‐CoMo‐LDH nanosheets. Under NIR‐II 1270 nm laser irradiation, the defect‐rich a‐Zn‐CoMo‐LDH nanosheets exhibit the optimal PDT performance compared with other a‐M‐CoMo‐LDH nanosheets, and also possess much higher ROS production activity (3.9 times) than that of the pristine a‐CoMo‐LDH, with a singlet oxygen quantum yield up to 1.86, which is the highest among all the reported PSs. After polyethylene glycol (PEG) modification, the a‐Zn‐CoMo‐LDH‐PEG nanosheets can function as an effective inorganic PS for PDT, effectively inducing cell apoptosis in vitro and eradicating tumors in vivo. Notably, transcriptome sequencing analysis and further molecular validation highlight the critical role of the apoptotic/p53/AMPK/oxidative phosphorylation signaling pathways in a‐Zn‐CoMo‐LDH‐PEG‐induced cancer cell apoptosis.

This work proposes a novel thermal-metallurgical model (TMM) that integrates the flat-top laser (FTL) heat source model with the non-isothermal Johnson–Mehl–Avrami (JMA) phase transformation model. The TMM can predict the phase composition of selective FTL melting (SFLM) high-performance superalloys from the mesoscale, providing insights for customized component properties. We apply the TMM to quantitatively predict the solid-state phase transformation behavior (SPTB) and final phase distribution in a three-layer, two-track SFLM process of IN738 superalloy. Additionally, we investigate the dependency of SPTB on process parameters. The results indicate that during the printing process, based on the relative sizes of the peak temperature and phase transformation temperature ranges during material cyclic heating, the precipitation of γ′ phase can be divided into precipitation-dissolution stage, precipitation stage, and stable stage, with the precipitation phase exhibiting a non-uniform distribution after the printing. Regarding laser power, scanning speed, and substrate preheating temperature, the substrate preheating temperature parameter significantly impacts the average volume fraction of γ′ phases (AVFG). When the substrate preheating temperature changes from 200 to 600 °C, the AVFG increases from 3.480 × 10⁻¹⁰ to 2.724 × 10⁻⁵. The FTL heat source model within the TMM was validated with data reported in the literature.

Single-pixel imaging (SPI) stands out in computational imaging for its simplicity and adaptability, yet its performance has been hampered by artifacts from translational motion. Existing solutions heavily rely on accurate motion modeling, requiring additional hardware and computational costs. In this Letter, we propose translational motion-agnostic SPI (TMA-SPI), a novel, to the best of our knowledge, single-object SPI framework agnostic to arbitrary translational motion. Our dual-domain optimization method leverages the translation invariance property of the amplitude spectrum in the Fourier domain, combined with the spatially finite and nonnegative constraints in the image domain, to produce a clear image of the moving object without any motion estimation or compensation. Through both simulation and the deployment of a real imaging prototype, we demonstrate its superior performance over the conventional SPI method. Our framework is expected to extend the applicability of SPI, offering significant improvements for dynamic sensing applications.

Sodium‐ion batteries (SIBs) suffer from sluggish kinetics, large volume change, and limited specific capacity due to the large radius of Na⁺. These issues can be solved through using covalent organic frameworks (COFs) as electrodes. Herein, an azatriangulenetrione‐containing COF (denoted as CityU‐33) was designed and synthesized as an electrode material for SIBs. Due to its inherent abundance of multiple redox‐active sites and fast intercalation kinetics, CityU‐33 delivered a high discharge capacity of 410.4 mAh g⁻¹ at 0.1 A g⁻¹ and showed remarkable long‐term cycling stability, where a discharge capacity of 288 mAh g⁻¹ at 0.2 A g⁻¹ with 97 % retention over 2000 cycles was achieved, making it the top COF electrode material for SIBs.

A meta-lens array-based Shack-Hartmann wavefront sensor has been developed to break the limits imposed by the size and curvature of traditional micro-lenses, which significantly improves both sampling density and angular resolution of phase measurement. Metasurface advances the field of optical phase measurement to smaller-scale complex wavefront characterization.

Image fusion aims to combine information from multiple source images into a single one with more comprehensive informational content. Deep learning-based image fusion algorithms face significant challenges, including the lack of a definitive ground truth and the corresponding distance measurement. Additionally, current manually defined loss functions limit the model’s flexibility and generalizability for various fusion tasks. To address these limitations, we propose ReFusion, a unified meta-learning based image fusion framework that dynamically optimizes the fusion loss for various tasks through source image reconstruction. Compared to existing methods, ReFusion employs a parameterized loss function, that allows the training framework to be dynamically adapted according to the specific fusion scenario and task. ReFusion consists of three key components: a fusion module, a source reconstruction module, and a loss proposal module. We employ a meta-learning strategy to train the loss proposal module using the reconstruction loss. This strategy forces the fused image to be more conducive to reconstruct source images, allowing the loss proposal module to generate a adaptive fusion loss that preserves the optimal information from the source images. The update of the fusion module relies on the learnable fusion loss proposed by the loss proposal module. The three modules update alternately, enhancing each other to optimize the fusion loss for different tasks and consistently achieve satisfactory results. Extensive experiments demonstrate that ReFusion is capable of adapting to various tasks, including infrared-visible, medical, multi-focus, and multi-exposure image fusion. The code is available at https://github.com/HaowenBai/ReFusion.

The efficiency of nitrate reduction reaction (NO3RR) at low nitrate concentration is predominantly hindered by the poor affinity of nitrate ions and competitive hydrogen evolution reaction (HER), particularly in neutral and acidic media. Here, an innovative strategy to leverage the interfacial electric field (IEF) is introduced to boost the NO3RR performance. By in situ constructing tannic acid‐metal ion (TA‐M²⁺) crosslinked structure on the electrode surface, the TA‐M²⁺‐CuO NW/Cu foam sample exhibits an exceptional Faraday efficiency of 99.4% at −0.2 V versus reversible hydrogen electrode (RHE) and 83.9% at 0.0 V versus RHE under neutral and acidic conditions, respectively. The computational studies unveil that the TA‐Cu²⁺ complex on the CuO (111) plane induces the increasing concentration of nitrate at the interface, accelerating NO3RR kinetics over HER via the IEF effect. This interfacial modulation strategy also contributes the enhanced ammonia production performance when it is employed on commercial electrode materials and flow reactors, exhibiting great potential in practical application. Overall, combined results illustrated multiple merits of the IEF effect, paving the way for future commercialization of NO3RR in the ammonia production industry.

The coupling between sound and flow likely influences the aerodynamics of bluff bodies, which deserves in-depth investigations. This paper presents a comprehensive experimental study of the effects of sound on the near wake flow and aerodynamic forces of a finite three-dimensional (3D) square cylinder in smooth flow and grid-generated turbulent flows. The study centers on the respective influences of a wider range of sound frequencies (1–2000 Hz) and sound pressure levels (60–100 dB) compared to previous studies. Employing a combination of particle image velocimetry and pressure measurements, the effects of sound on the aerodynamic characteristics, specifically, the near wake flow field, vortex shedding dynamics and pressure distributions are investigated. The spectral analysis and proper orthogonal decomposition analysis are conducted to gain deeper insights into the effects of sound on the coherent structures of the aerodynamic forces around the square cylinder. The results demonstrate that the influences of sound in modulating the wind pressure distributions on the cylinder are dependent on both the sound frequency and sound pressure level. The findings also highlight the occurrence of acoustic resonance and its impact on vortex-shedding behaviors and flow fields, demonstrating the sensitivity of these phenomena to specific sound frequencies and sound pressure levels. Furthermore, these sound-induced change phenomena can be weakened when turbulence is added to the approaching flows. The degree of this attenuation is found to vary depending on specific characteristics of a turbulent flow, such as turbulence intensities and integral length scales.