State Key Laboratory of Catalysis

Overall water splitting based on particulate photocatalysts is an easily constructed and cost-effective technology for the conversion of abundant solar energy into clean and renewable hydrogen energy on a large scale. This promising technology can be achieved in a one-step excitation system using a single photocatalyst or via a Z-scheme process based on a pair of photocatalysts. Ideally, such photocatalysis will proceed with charge separation and transport unaffected by recombination and trapping, and surface catalytic processes will not involve undesirable reactions. This review summarizes the basics of overall water splitting via both one-step excitation and Z-scheme processes, with a focus on standard methods of determining photocatalytic performance. Various surface engineering strategies applied to photocatalysts, such as cocatalyst loading, surface morphology control, surface modification and surface phase junctions, have been developed to allow efficient one-step excitation overall water splitting. In addition, numerous visible-light-responsive photocatalysts have been successfully utilized as H2-evolution or O2-evolution photocatalysts in Z-scheme overall water splitting. Prototype particulate immobilization systems with photocatalytic performances comparable to or drastically higher than those of particle suspension systems suggest the exciting possibility of the large-scale production of low-cost renewable solar hydrogen.

It is widely accepted within the community that to achieve a sustainable society with an energy mix primarily based on solar energy we need an efficient strategy to convert and store sunlight into chemical fuels. A photoelectrochemical (PEC) device would therefore play a key role in offering the possibility of carbon-neutral solar fuel production through artificial photosynthesis. The past five years have seen a surge in the development of promising semiconductor materials. In addition, low-cost earth-abundant co-catalysts are ubiquitous in their employment in water splitting cells due to the sluggish kinetics of the oxygen evolution reaction (OER). This review commences with a fundamental understanding of semiconductor properties and charge transfer processes in a PEC device. We then describe various configurations of PEC devices, including single light-absorber cells and multi light-absorber devices (PEC, PV-PEC and PV/electrolyser tandem cell). Recent progress on both photoelectrode materials (light absorbers) and electrocatalysts is summarized, and important factors which dominate photoelectrode performance, including light absorption, charge separation and transport, surface chemical reaction rate and the stability of the photoanode, are discussed. Controlling semiconductor properties is the primary concern in developing materials for solar water splitting. Accordingly, strategies to address the challenges for materials development in this area, such as the adoption of smart architectures, innovative device configuration design, co-catalyst loading, and surface protection layer deposition, are outlined throughout the text, to deliver a highly efficient and stable PEC device for water splitting.

Doping single-atom metals into MoS₂ matrix can efficiently trigger the electrocatalytic hydrogen evolution activity of inert S atoms on 2D MoS₂ surface and meanwhile enhance catalytic stability and anti-poison ability.

The efficiency of planar CH₃NH₃PbI₃ perovskite solar cells has been improved up to 19.62% using an ionic liquid to modify the TiO₂ electron transport layer, and the <italic>J</italic>–<italic>V</italic> hysteresis is completely eliminated.

Novel non-precious-metal catalysts encapsulated in N-doped carbon nanotubes exhibit high activity and remarkable stability towards hydrogen evolution reaction (HER) in acidic medium.

With these guidelines, we aim to unite the lignin-first biorefining research field around best practices for performing or reporting feedstock analysis, reactor design, catalyst performance, and product yields.

Developing sustainable energy resources is one of the most urgent missions for human beings as increasing energy demand is in drastic conflict with limited global fossil fuels. Among the various types of sustainable energy resources, solar energy is considered to be promising due to its inexhaustible supply, universality, high capacity, and environmental friendliness. However, natural solar irradiation is decentralized, intermittent and fluctuates constantly. Therefore, effective utilization of solar energy in a clean, economic, and convenient way remains a grand challenge.

Single layer graphene encapsulating earth-abundant 3d transition metal nanoparticles exhibits excellent activity and durability for water oxidation, even exceeding IrO₂.

Coordinatively unsaturated Ni–N active sites facilitate CO₂electroreduction and inhibit the competitive hydrogen evolution reaction, demonstrating selective and high-rate CO₂electroreduction.

plane. This single-atom dispersed Co-N-C catalyst presents excellent performance for the chemoselective hydrogenation of nitroarenes to produce azo compounds under mild reaction conditions.

As the largest renewable carbon resource, lignocellulosic biomass has great potential to replace fossil resources for the production of high-value chemicals, in particular organic oxygenates. Catalytic transformations of lignocellulosic biomass using solar energy have attracted much recent attention, because of unique reactive species and reaction patterns induced by photo-excited charge carriers or photo-generated reactive species as well as the mild reaction conditions, which may enable the precise cleavage of target chemical bonds or selective functionalisation of specific functional groups with other functional groups kept intact. Here, we present a critical review on recent advances in the photocatalytic transformation of lignocellulosic biomass with an emphasis on photocatalytic cleavage of C-O and C-C bonds in major components of lignocellulosic biomass, including polysaccharides and lignin, and the photocatalytic valorisation of some key platform molecules. The key issues that control the reaction paths and the reaction mechanism will be discussed to offer insights to guide the design of active and selective photocatalytic systems for biomass valorisation under mild conditions. The challenges and future opportunities in photocatalytic transformations of lignocellulosic biomass are also analysed.

Monodispersed nickel phosphide nanocrystals (NCs) with different phases were successfully synthesized. The Ni₅P₄ NCs, with a solid structure, exhibited higher catalytic activity than the Ni₁₂P₅ and Ni₂P NCs.

15.07% efficiency for flexible perovskite solar cells is achieved using low temperature TiO₂.

Rational construction of dual cocatalysts corresponding to different facets with photogenerated charge separation.

Understanding photogenerated charge separation on the nano- to micrometer scale is the key to optimizing the photocatalytic solar energy conversion efficiency. In the past few years, spatially resolved surface photovoltage (SPV) techniques have opened up new opportunities to directly image localized charge separation at surfaces or interfaces of photocatalysts and thus provided deep insights into the understanding of photocatalysis. In this review, we reviewed the SPV techniques, in particular Kelvin probe force microscopy (KPFM) based spatially resolved SPV techniques and their applications in charge separation imaging. The SPV principle was explained with regard to charge separation across a space charge region (SCR) in a depletion layer at a semiconductor surface and to diffusion. The center of charge approach, relaxation of SPV signals and measurement of SPV signals including SPV transients with fixed capacitors were described. Then, we highlighted the fundamental principle and development of the spatially resolved SPV technique and its application in photocatalysis. Important progress made by the spatially resolved SPV technique in this group is given, focusing on understanding the nature of charge separation and providing insights into the rational design of highly efficient photocatalytic systems. Finally, we discuss the prospects of further developments of the spatially resolved SPV technique that would help in understanding photocatalysis for solar energy conversion with high temporal resolution and operated under in operando conditions.

Two-dimensional (2D) materials are characterised by their strong intraplanar bonding but weak interplanar interaction. Interfaces between neighboring 2D layers or between 2D overlayers and substrate surfaces provide intriguing confined spaces for chemical processes, which have stimulated a new area of "chemistry under 2D cover". In particular, well-defined 2D material overlayers such as graphene, hexagonal boron nitride, and transition metal dichalcogenides have been deposited on solid surfaces, which can be used as model systems to understand the new chemistry. In the present review, we first show that many atoms and molecules can intercalate ultrathin 2D materials supported on solid surfaces and the space under the 2D overlayers has been regarded as a 2D nanocontainer. Moreover, chemical reactions such as catalytic reactions, surface adlayer growth, chemical vapor deposition, and electrochemical reactions occur in the 2D confined spaces, which further act as 2D nanoreactors. It has been demonstrated that surface chemistry and catalysis are strongly modulated by the 2D covers, resulting in weakened molecule adsorption and enhanced surface reactions. Finally, we conclude that the confinement effect of the 2D cover leads to new chemistry in a small space, such as "catalysis under cover" and "electrochemistry under cover". These new concepts enable us to design advanced nanocatalysts encapsulated with 2D material shells which may present improved performance in many important processes of heterogeneous catalysis, electrochemistry, and energy conversion.

Spatial charge separation achieved on the anisotropic facets of high symmetry SrTiO₃nanocrystals for highly efficient photocatalytic overall water splitting.

High-density coordination unsaturated copper(<sc>i</sc>)–nitrogen embedded in graphene demonstrates a high performance and stability in primary zinc–air batteries with ultralow catalyst loading.

The integrated architecture enables the Ta₃N₅photoanode to approach the theoretical photocurrent limit for solar water splitting.

Photocatalytic overall water splitting on TiO₂-based photocatalysts is determined by both thermodynamics and kinetics simultaneously.