Enhanced yield of methanol using rGO-Bi₂S₃/CuO heterojunction photocatalyst for CO₂ reduction

A visible light-induced rGO-Bi₂S₃/CuO S-scheme heterojunction photocatalyst is explored for the production of methanol and formic acid through photocatalytic CO₂ reduction. In this work, the effect of CuO loading on rGO-Bi₂S₃ nano-hollow flower composite are investigated to improve the yield and selectivity of methanol production. The synthesised rGO-Bi₂S₃/CuO nanocomposite, being a highly efficient and robust photocatalyst, exhibits the maximum methanol yield of 423.52 μmol g_cat.⁻¹ h⁻¹ along with formic acid. CuO loading on rGO-Bi₂S₃ is responsible for achieving the maximum photocatalytic activity of the rGO-Bi₂S₃/CuO photocatalyst, the narrowest band gap, the lowest recombination rate of electron–hole pairs, and the increased specific surface area for CO₂ capture among all the related photocatalysts, rGO-Bi₂S₃, pristine Bi₂S₃, and Bi₂S₃/CuO nanocomposite. The selectivity of methanol is improved to 98.6% by the rGO-Bi₂S₃/CuO heterojunction photocatalyst. The absorption edge (652.4 nm) of the rGO-Bi₂S₃/CuO photocatalyst clearly exhibits outstanding visible light absorption and enhanced photo carrier transportation power.