Electro-(Photo)catalysis for Concurrent Evolution of Hydrogen and High Value-Added Chemicals

Green hydrogen (H2) has been identified as a promising alternative to fossil fuel. Compared with traditional methods, such as steam methane reforming and coal gasification, electro-(photo)catalysis of water splitting provides a clean and sustainable way to produce green H2. However, electro-(photo)catalytic water splitting still suffers from sluggish kinetics and high-power consuming. Chemical-assisted electro-(photo)catalytic water splitting, with concurrent evolution of H2 and high value-added chemicals (HVACs), has recently drawn great attention. In such system, oxygen evolution process has been replaced by small organics or other chemicals with low oxidation reaction potential to reduce the energy gap. In this review, we will review recent important advances on how to design the electro-(photo)catalytic systems for concurrent evolution of H2 and HVACs. We first introduce the design principles and fundamentals of chemical-assisted electro-/photocatalytic water splitting. Then we focus on the different reaction types at anode for electro-(photo)catalysis, in which specific chemicals, especially small molecule, can be produced from biomass, alkyl alcohols and so on, with high efficiency and selectivity, coupled with promoted H2 generation. Finally, major challenges and perspectives relevant to the catalyst design, catalytic mechanisms and application of electro-(photo)catalytic concurrent evolution of H2 and HVACs will be provided.