Photocatalytic Carbon Dioxide Reduction at p-Type Copper(I) Iodide

A p-type semiconductor, CuI, has been synthesized, characterized, and tested as a photocatalyst for CO₂ reduction under UV/Vis irradiation in presence of isopropanol as a hole scavenger. Formation of CO, CH₄ , and/or HCOOH was observed. The photocatalytic activity of CuI was attributed to the very low potential of the conduction band edge (i.e., -2.28 V vs. NHE). Photocurrents generated by the studied material confirm a high efficiency of the photoinduced interfacial electrontransfer processes. Our studies show that p-type semiconductors may be effective photocatalysts for CO₂ reduction, even better than extensively studied n-type titanium dioxide, owing to the low potential of the conduction band edge.