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Nanometal materials play very important roles in solar-to-chemical energy conversion due to their unique catalytic and optical characteristics. They have found wide applications from semiconductor photocatalysis to rapidly growing surface plasmon-mediated heterogeneous catalysis. The recent research achievements of nanometals are reviewed here, with regard to applications in semiconductor photocatalysis, plasmonic photocatalysis, and plasmonic photo-thermocatalysis. As the first important topic discussed here, the latest progress in the design of nanometal cocatalysts and their applications in semiconductor photocatalysis are introduced. Then, plasmonic photocatalysis and plasmonic photo-thermocatalysis are discussed. A better understanding of electron-driven and temperature-driven catalytic behaviors over plasmonic nanometals is helpful to bridge the present gap between the communities of photocatalysis and conventional catalysis controlled by temperature. The objective here is to provide instructive information on how to take the advantages of the unique functions of nanometals in different types of catalytic processes to improve the efficiency of solar-energy utilization for more practical artificial photosynthesis.

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The photothermal conversion of CO2 provides a straightforward and effective method for the highly efficient production of solar fuels with high solar-light utilization efficiency. This is due to several crucial features of the Group VIII nanocatalysts, including effective energy utilization over the whole range of the solar spectrum, excellent photothermal performance, and unique activation abilities. Photothermal CO2 reaction rates (mol h(-1) g(-1)) that are several orders of magnitude larger than those obtained with photocatalytic methods (μmol h(-1) g(-1)) were thus achieved. It is proposed that the overall water-based CO2 conversion process can be achieved by combining light-driven H2 production from water and photothermal CO2 conversion with H2. More generally, this work suggests that traditional catalysts that are characterized by intense photoabsorption will find new applications in photo-induced green-chemistry processes.

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Exploiting noble-metal-free cocatalysts is of huge interest for photocatalytic water splitting using solar energy. As an effi cient cocatalyst in photocatalysis, MoS 2 is shown promise as a low-cost alternative to Pt for hydrogen evolution.Here we report a systematical study on controlled synthesis of MoS 2 with layer number ranging from ≈1 to 112 and their activities for photocatalytic H 2 evolution over commercial CdS. A drastic increase in photocatalytic H 2 evolution is observed with decreasing MoS 2 layer number. Particularly for the single-layer (SL) MoS 2 , the SL-MoS 2 /CdS sample reaches a high H 2 generation rate of ≈2.01 × 10 −3 M h −1 in Na 2 S-Na 2 SO 3 solutions and ≈2.59 × 10 −3 M h −1 in lactic acid solutions, corresponding to an apparent quantum effi ciency of 30.2% and 38.4% at 420 nm, respectively. In addition to the more exposed edges and unsaturated active S atoms, valence band-XPS and Mott-Schottky plots analysis indicate that the SL MoS 2 has the more negative conduction band energy level than the H + /H 2 potential, facilitating the hydrogen reduction.

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Efficient photocatalytic conversion of CO2 into CO and hydrocarbons by hydrous hydrazine (N2H4⋅H2O) is achieved on SrTiO3/TiO2 coaxial nanotube arrays loaded with Au-Cu bimetallic alloy nanoparticles. The synergetic catalytic effect by the Au-Cu alloy nanoparticles and the fast electron-transfer in SrTiO3/TiO2 coaxial nanoarchitecture are the main reasons for the efficiency, while N2H4⋅H2O as the H source and electron donor provides a reducing atmosphere to protect the surface Cu atoms from oxidation, therefore maintaining the alloying effect which is the basis for the high photocatalytic activity and stability. This approach opens a feasible route to enhance the photocatalytic efficiency, which also benefits the development of photocatalysts and co-catalysts.