Photocatalytic Reduction of CO2 to CO and CH4 in Aqueous Suspensions of Modified Heterojunction Semiconductor Cu–MgO/SiC/ZnO

The reaction of photocatalytic reduction of CO2 with water into CO and CH4 in suspensions of the heterojunction semiconductor SiC/ZnO with copper metal Cu (0.5 wt %) deposited on its surface has been studied. The formation of CO and a small amount of CH4 has been established; the methane yield increases fourfold and the CO yield sharply decreases when MgO is additionally deposited on the semiconductor surface. The maximum methane yield is achieved at a MgO content of 1 wt %; however, with a further increase in the amount of MgO, the CH4 yield decreases. The mechanism of CO2 reduction to CO in a two-electron process and to CH4 in an eight-electron process is discussed.