Dong Liu

Nanjing University of Science and Technology | NJUST · School of Energy and Power Engineering

Microfluidics refers to the technology of controlling or operating minute amounts of fluids in microchannels with the characteristic dimension of the submillimeter scale. Ascribing to the extremely large specific surface area, microfluidics inherently allows the potential in facilitating energy and mass transport. To date, microfluidic devices have...

Plasmon-mediated photocatalytic water splitting holds promise for efficient solar energy harvesting. Experimental studies have shown that “hot spots” in an assembly of plasmonic nanoclusters, which is the real case for practical applications, are beneficial for photocatalysis, but the interactions between different nanoclusters are difficult to obs...

The community of electrochemical CO2 reduction is almost exclusively focused on gaseous CO2-fed electrolyzers. Here, we proposed a pressurized CO2-Captured solution electrolyzer to produce solar Fuel of CO (abbreviated "CCF") without the need to regenerate gaseous CO2. Specifically, we developed an experimentally validated multiscale model to quant...

As a promising technology, microreactors have been regarded as a potential candidate for heterogeneous catalytic reactions as they inherently allow the superior advantages of precise flow control, efficient reactant transfer, flexible operation, etc. However, the wide market penetration of microreactors is still facing severe challenges. One of the...

Studies on the thermophysical properties of H2O/CO2 mixtures for supercritical conditions, typical for a promising power generation system are far fewer than those for typical conditions of CO2 capture and storage (lower temperatures and pressures). In the previous heat transfer studies, we have set up a high-temperature and high-pressure apparatus...

Hydrogen production from water electrolysis provides an effective bridge between the existing energy system and the layout of green renewable energy. Electrochemical hydrogen gas evolution on the electrode surface will occupy the limited active sites thus significantly increasing the reaction overpotential. It is crucial to study and optimize the b...

Photocatalytic water splitting is a promising route for hydrogen production and solar energy storage. Plasmon-mediated water splitting has the potential to harvest photons with longer wavelengths compared with semiconductor-based photocatalysis. However, the mechanism of plasmon-induced charge transfer, the determining step of photochemistry, is no...

In this work, we experimentally investigated the deterioration and instability of heat transfer to H2O/CO2 mixtures in the near-critical region, following our series of works on their normal and enhanced heat transfer, hydraulic resistance and thermophysical properties. The experimental pressure is 24 MPa, temperatures are 330-400°C, CO2 mass fract...

Hydraulic resistance of H2O/CO2 mixtures for supercritical conditions, typical for a promising power generation system, has been a knowledge gap. In this work, it was experimentally investigated in a high-temperature, high-pressure, and multi-function apparatus and was further correlated. For the experimental conditions, the CO2 mass fractions were...

The aqueous electrochemical CO2 reduction to valuable products is seen as one of the most promising candidates to achieve carbon neutrality yet still suffers from poor selectivity and lower current density. Highly efficient CO2 reduction significantly relies on well‐constructed electrode to realize efficient and stable triple‐phase contact of CO2,...

The salient question addressed in this work is whether and how photovoltaic-biased photoelectrocatalysis (PV-PEC) can fairly and practically be as competitive as photovoltaic-powered electrocatalysis (PV-EC) for solar-driven carbon dioxide reduction (CO2RR). It was argued that to fairly evaluate PV-PEC and PV-EC CO2RR approaches in terms of techno-...

Solar energy storage in the form of chemical energy is considered a promising alternative for solar energy utilization. High-performance solar energy conversion and storage significantly rely on the sufficient active surface area and the efficient transport of both reactants and charge carriers. Herein, the structure evolution of titania nanotube p...

We demonstrated an efficient solar photovoltaic-powered electrochemical CO2 reduction device with a high-pressure CO2-captured liquid feed. In an “air-to-barrel” picture, this device holds promise to avoid both high-temperature gaseous CO2 regeneration and high energy-cost gas product separation steps, while these steps are necessary for devices wi...

Photoelectrochemical Redox Batteries In article number 2200469, Qiang Li, Rong Chen, Liang An and co‐workers present a comprehensive review of research and development progress in photoelectrochemical redox batteries from materials to devices. The fundamental understanding of the energy level matching, transport mechanisms, and performance indicato...

A porous volumetric receiver is the key component in concentrated solar power systems. In this paper, we investigate the effects of volumetric parameter models on the heat collection efficiency of the volumetric receiver by numerical simulations with the combination of local thermal non-equilibrium and discrete ordinate methods. Seven volumetric co...

Single‐Atom Catalysts The low loading of single‐atom catalysts makes it difficult to improve their overall activity. In article number 2200073, Ang Li, Erjun Kan, Li Song, Jinlong Gong, and co‐workers report a chemical scissors strategy to saturate the anchoring sites for single atoms, which elevates the loading of Pd single atoms even on bare subs...

The photoelectrochemical redox battery (PRB) has been regarded as an alternative candidate for large‐scale solar energy capture, conversion, and storage as it combines the superior advantages of photoelectrochemical devices and redox batteries. As an emerging solar energy utilization technology, significant progress has been made towards promoting...

Herein, an in-situ visual method was developed to determine the residence time characteristic of a typical gas-liquid Taylor reacting flow in a microchannel reactor. Nitrobenzene hydrogenation was chosen as a reference heterogeneous reaction. The obtained results demonstrated the feasibility of the proposed in-situ visual method in determining the...

Atomically dispersed metal catalysts often exhibit high catalytic performances, but the metal loading density must be kept low to avoid the formation of metal nanoparticles, making it difficult to improve the overall activity. Diverse strategies based on creating more anchoring sites (ASs) have been adopted to elevate the loading density. One probl...

Supercritical H2O/CO2 mixtures (650 K–973 K and 25 MPa, not far away from the critical temperature and pressure of water) have recently been used as the working fluid for a novel power generation system with higher efficiency and zero pollutant emission compared to conventional coal-fired power plants. The knowledge of the diffusion of these mixtur...

Efficient charge separation is crucial for solar energy conversion in semiconductor-based systems. Creating p-n junction is an effective strategy to enhance charge separation because the built-in electric field could inhibit charge recombination. However, in many situations, the high reaction barrier will limit the surface reaction rate, resulting...

Selective electrochemical CO2 reduction reaction (CO2RR) requires efficient triple-phase contact of CO2 molecules, electrolyte and active sites of electrocatalyst. To achieve this, studies have sought to use surface modifications to electrodes. However, the stability of these modifications and their effects on the intrinsic properties of electrodes...

Electrocatalytic generation of nanometre gas bubbles (nanobubbles) and their tuning are important for many energy and chemical processes. Studies have sought to use indirect or ex situ methods to investigate the dynamics and properties of nanobubbles, which are of fundamental interest. Alternatively, we present a molecular dynamics simulation metho...

Heat transfer to supercritical H2O/CO2 mixtures (24 MPa, 310 to 430 °C, and CO2 mass fractions up to 18.5%), the working fluids of a novel power generation system with coal gasified in supercritical water, was experimentally investigated for typical working conditions of this system. For these conditions, i.e., high mass velocities (above 1200 kg m...

Controlling the products, i.e. achieving high selectivity, is essential yet challenging for many chemical processes. So far, ex/in situ methods have been reported to prepare selective catalysts; here, we present a distinct operational strategy. To demonstrate its power and simplicity, a high-pressure artificial photosynthetic device (HiPAD) was des...

Flexible transparent electrodes are in significant demand in applications including solar cells, light-emitting diodes, and touch panels. The combination of high optical transparency and high electrical conductivity, however, sets a stringent requirement on electrodes based on metallic materials. To obtain practical sheet resistances, the visible t...

Supercritical H2O/CO2 mixtures are the working fluids in a novel power generation system with coal gasified in supercritical water, but their heat transfer behaviors have received less attention compared with those of the supercritical water. Here, we experimentally investigated the heat transfer to these important mixtures. First, a stable and acc...

Photocatalytic CO2 reduction reaction (CRR) represents a prospective route for the clean utilization of greenhouse gas CO2 and solar energy, and cuprous oxide (Cu2O) is a favourable material for CRR to avoid excess generation of hydrogen through the competitive hydrogen evolution reaction (HER). However, the application of Cu2O-based photocatalysts...

The supercritical H2O/CO2 mixture is the working fluid to drive a turbine in a novel power generation system with coal gasified in supercritical water. This system is promising because of zero pollution emission in contrast to the conventional coal-fired power plant. Heat transfer coefficients of the supercritical H2O/CO2 mixtures are important to...

Supercritical H 2 O/CO 2 mixtures are the working fluid in a novel power generation system with coal gasified in supercritical water, so their heat transfer behaviors are important to design heat transfer devices. However, heat transfer to supercritical mixtures has received few attention. Here, we designed and established an apparatus to measure t...

Solar thermochemical conversion is an effective way to store unstable solar energy as chemical energy in fuels; and thus, it is of great significance in clean energy economy. Using thermochemical catalyst as the solar energy absorber directly is an advanced way to achieve high efficiency because of the cancellation of the heat resistance resulting...

This work theoretically and experimentally presents a high-efficiency solar system which integrates photovoltaic cells and methanol thermal decomposition to make full use of the full-spectrum solar energy. In this optimized system, spectral beam splitting technology is used to split the solar spectrum into several wavebands. The spectrum suitable f...

Structural colors of high purity and brightness are desired in various applications. This study presents a general strategy of selecting the appropriate material and thickness of each layer to create high‐purity reflective colors in a classic asymmetric Fabry–Pérot cavity structure based on a dielectric–absorber–dielectric–metal multilayered config...

The demand for high‐performance absorbers in the microwave frequencies, which can reduce undesirable radiation that interferes with electronic system operation, has attracted increasing interest in recent years. However, most devices implemented so far are opaque, limiting their use in optical applications that require high visible transparency. He...

Enhancing light absorption in two-dimensional (2-D) materials using simple planar structures is important for the development of large-area atomic-scale photonic devices but also has been a major challenge. We theoretically present a general strategy to create an atomically thin planar metasurface consisting of a semiconductor monolayer (replacing...

A four-layer metallodielectric planar thermal emitter is designed and optimized to tailor the spectral near-field radiative flux in a nano-gap thermophotovoltaic (TPV) system. The structure contains an ultra-thin refractory metallic layer (tungsten) sandwiched by two dielectric (hafnia) layers sitting on a metallic substrate. The theoretical calcul...

The achievement of perfect light absorption in ultrathin semiconductor materials is not only a long‐standing goal, but also a critical challenge for solar energy applications, and thus requires a redesigned strategy. Here, a general strategy is demonstrated both theoretically and experimentally to create a planar metasurface absorber comprising a 1...

A four-layer planar metallodielectric structure is designed to be the emitter for a nano-gap TPV device. The emitter showed versatile manipulation of near-field radiative transfer mainly by controlling the propagating and frustrated modes. The system efficiency (at radiative limit) has the potential to reach or exceed other state-of-the-art designs...

Here, we designed volumetric receivers from the angle of their normal absorptance and hemispherical volumetric emittance. We showed that the optimal receiver with the reticulated porous structure to date should have 95% porosity, 0.4 mm average pore diameter and 8 mm length. This receiver has both high normal absorptance and low hemispherical volum...

Ultrathin planar absorbing layers, including semiconductor and metal films, and 2D materials, are promising building blocks for solar energy harvesting devices but poor light absorption has been a critical issue. Although interference in ultrathin absorbing layers has been studied to realize near perfect absorption at a specific wavelength, achievi...

We show theoretically that 2D rectangular gratings on the surface of GaSb can serve as an “anti-reflection” pattern for nano-gap thermophotovoltaic (TPV) devices, which significantly enhances near-field radiative flux from the emitter to a GaSb cell, thus improving output power and conversion efficiency. The system in this study is a 200-nm gap TPV...

Two challenging problems still remain for optical absorbers consisting of an ultrathin planar semiconductor film on top of an opaque metallic substrate. One is the angle-insensitive mechanism and the other is the system design needed for broadband solar energy harvesting. Here, first we theoretically demonstrates that the high refractive index, ins...

Ultrathin planar absorbers hold promise in solar energy systems because they can reduce the material, fabrication, and system cost. Here, we present a general strategy of effective medium design to realize ultrathin planar broadband absorbers. The absorber consists of two ultrathin absorbing dielectrics to design an effective absorbing medium, a tr...

Hematite holds promise for photoelectrochemical (PEC) water splitting due to its stability, low-cost, abundance and appropriate bandgap. However, it suffers from a mismatch between the hole diffusion length and light penetration length. We have theoretically designed and characterized an ultrathin planar hematite/silver nanohole array/silver substr...

The effective medium theory (EMT) can be used for fast and approximate calculations of inhomogeneous media’s optical properties, which is helpful for considerably reducing computation times for designing the thermal radiative properties of particulate materials. Because EMT has mostly been limited to systems with characteristic sizes considerably s...

Accepted for presentation at 19th Symposium on Thermophysical Properties, to be held in Boulder, CO, USA on June, 2015. Abstract available at http://thermosymposium.boulder.nist.gov/pdf/Abstract_3181.pdf

Coal ash inevitably forms deposits as combustion residue on the walls and heat transfer surfaces of coal-fired boilers. Ash deposits decrease the boiler efficiency, reduce the generating capacity, and cause unscheduled outages. The radiative heat transfer is the major heat transfer mechanism in utility boilers; thus, the ash deposit emissivity is c...

Opacified aerogels are particulate thermal insulating materials in which micrometric opacifier mineral grains are surrounded by silica aerogel nanoparticles. A geometric model was developed to characterize the spectral properties of such microsize grains surrounded by much smaller particles. The model represents the material's microstructure with t...

500 million tons of coal fly ash are produced worldwide every year with only 16% of the total amount utilized. Therefore, potential applications using fly ash have both environmental and industrial interests. Unburned carbon concentration measurements are fundamental to effective fly ash applications. Current on-line measurement accuracies are stro...

Opacified silica aerogels are composite insulating materials containing silica nanoparticles and microsize opacifier grains. The radiative heat transfer in this dispersed medium was analyzed using a realistic microstructure model to calculate the opacified aerogel’s optical properties. The aerogel matrices were simulated using aggregates generated...

The average normal effective emissivity is widely used for calibration since it depends only on the intrinsic cavity characteristics; thus, it is an important parameter for blackbody designs and evaluations. Nonaxisymmetric cavities are widely used as standard blackbody sources and cryogenic solar absolute radiometers. The finite volume method is m...

Turbulent particle cloud temperatures in the superheater pendant region are critical in coal-fired utility boilers not only for the interactions between turbulence and radiative heat transfer, but also for the ash deposit slagging and fouling on superheater tubes. The false infrared particle temperature fluctuations due to the pendant wake dynamics...

Non-axisymmetric cavities are widely used as standard blackbody sources for radiation thermometry. The integrated effective emissivity is central to the blackbody design. Integrated effective emissivities are numerically calculated for non-isothermal, non-axisymmetric cavities. The average relative deviation is 0.087% when compared with Monte-Carlo...

The infrared temperature fluctuations on a plate in a coal-fired combustor were measured and the effects of participating media on infrared measurement were revealed. The experimental results were analyzed in both the time and frequency domains. It is found the fluctuations have both random and periodic characteristics. The periodic frequency is id...