Nanostructured heterogeneous photocatalyst materials for green synthesis of valuable chemicals

The photocatalytic process employing nanostructured semiconductor materials has attracted great attention in energy production, CO2 reduction, and water/air purification for decades. Recently, applying heterogeneous photocatalyst for the synthesis of valuable chemicals is gradually emerging and considered as a promising process for the conversion of cheap resources (i.e., biomass derivatives, polyols, and aromatic hydrocarbons). Compared with traditional thermal catalytic approaches, the photocatalytic process provides a mild reaction condition and flexible platform (photocatalyst) that allows precise tweaking of reaction intermediates and reaction pathways, thus resulting in fine control of the selective synthesis of specialized chemicals that are challenging for thermal catalysis. In this review, we summarize recent achievements in photocatalytic synthesis of various industrial important chemicals via photo-oxidative and photo-reductive processes. The selective oxidation of alcohols and aromatics, epoxidation of alkenes, hydrogenation of gaseous molecules and hydrocarbons, and coupling reactions by means of various photocatalysts including metal oxides, supported plasmonic metal nanostructures, conjugated organic polymers, anchored homogeneous catalysts, and dye-sensitized heterostructures are discussed from a material perspective. In addition, fundamental understandings of reaction mechanisms and rational design of nanostructured photocatalysts for enhancing efficiency, selectivity, and stability are discussed in detail.