Gold and Copper Nanoparticles Supported on Cerium(IV) Oxide—A Photocatalyst Mineralizing Organic Acids under Red Light Irradiation

Gold and copper nanoparticles supported on cerium(IV) oxide (CeO2) powder, which were prepared using a simple multistep photodeposition method, showed strong absorptions at around λ=620 nm attributed to the surface plasmon resonance of Cu‐Au nanoparticles and exhibited a higher level of activity than that of Au/CeO2 in the mineralization of organic acids (formic acid and acetic acid) in aqueous suspensions under light irradiation (λ=640 nm) from a red light‐emitting diode. The action spectrum in the mineralization of formic acid indicates that this mineralization involved a photoinduced step by the SPR of Cu‐Au supported on CeO2. The apparent quantum efficiency reached 7.5 % at λ=625 nm and 5.2 % even at λ=700 nm.