Sunlight‐Driven Production of Methylcyclohexane from Water and Toluene Using ZnSe:Cu(In,Ga)Se2‐based Photocathode

A three-dimensional reaction field composed of a thick, porous TiO2 layer decorated with Pt and an anionic ionomer was fabricated on the surface of a membrane photocathode assembly (MPA). This MPA comprised (ZnSe)(0.85)(CuIn0.7Ga0.3Se2)(0.15) (ZnSe : CIGS) particles that promoted the photoelectrochemical (PEC) production of methylcyclohexane (MCH) from toluene and water. The Pt/TiO2 layer provided selective active sites for MCH production as well as reactant supply pathways. A tandem PEC cell consisting of the Pt/TiO2-modified ZnSe : CIGS MPA and a photoanode exhibited spontaneous MCH production with a solar-to-MCH (STMCH) conversion efficiency as high as 0.32 %. This is the first-ever report of sunlight-driven overall MCH production without any assistance of external bias voltages and demonstrates the feasibility of driving this reaction as an artificial photosynthesis.