Designing atomic Ni/Cu pairs on a reactive BiOCl surface for efficient photo-chemical HCO3−-to-CO conversion

Abstract

Solar-driven conversion of bicarbonate (HCO₃⁻) to carbonaceous fuels and/or chemicals provides an alternative route for the development of sustainable carbon economies. However, promoting the HCO₃⁻ reduction rate and tuning product selectivity remain significant challenges. This study reports the identification of isolated Ni/Cu atomic pairs dispersed on a BiOCl surface (Ni₁/Cu₁-BOC) as a promising candidate for efficient HCO₃⁻ reduction under UV-vis light irradiation. The optimized photocatalyst exhibits a high CO formation rate of 157.1 μmol g⁻¹ h⁻¹ with nearly 100% selectivity, even in the absence of added proton sources, sacrificial agents, or sensitizers. Experimental and theoretical investigations reveal that the atomically dispersed Ni/Cu pairs facilitate the protonation of HCO₃⁻ to CO₂, which then undergoes a H⁺-assisted reduction pathway to produce CO, with *COOH as the intermediate. The synergistic effects of the Ni/Cu atomic pairs simultaneously promote the HCO₃⁻-to-CO₂ conversion and the subsequent CO₂-to-CO reduction, providing valuable insights for the development of efficient diatomic catalysts for photocatalytic HCO₃⁻ reduction reactions.