A Red Light-Inducible Copper-Photodeposited All-Solid-State Z-Scheme Photocatalyst for Carbon Dioxide Reduction to Methane Using Water as an Electron Donor

Abstract

We selectively loaded various amounts of copper (Cu) as a cocatalyst for the reduction reaction onto zinc rhodium oxide (ZnRh2O4 (ZRO)) in a heterojunction photocatalyst and silver (Ag)-inserted ZRO and bismuth vanadium oxide (Bi4V2O11 (BVO)) solid-state photocatalyst (ZRO/Ag/BVO (ZAB)) to form Cu/ZAB. The amount of deposited Cu was controlled by the photodeposition time to generate Cu/ZAB with up to 0.14 wt % Cu cocatalyst vs ZAB. All the prepared Cu/ZAB samples accomplished overall water splitting under red light irradiation at a wavelength of 700 nm, enhancing the stoichiometric evolutions of hydrogen and oxygen from water compared with bare ZAB. Moreover, the apparent quantum efficiency increased up to 0.13 wt % Cu cocatalyst, which thereafter tended to decrease. The optimized Cu/ZAB photocatalyst was confirmed to reduce carbon dioxide (CO2) to methane using water as an electron donor and proton source under irradiation with visible light at a wavelength of 700 nm, which is, to our knowledge, the longest wavelength reported to date for CO2 reduction.