Vacancies and electronic effects enhanced photoelectrochemical activity of Cu-doped Bi2Se3 for efficient CO2 reduction to formate

Abstract

Photoelectrochemical CO2 reduction to formate offers an appealing pathway for alleviating energy and environmental problems. However, achieving high product selectivity and low overpotential in CO2 activation remains challenging. In this work, we synthesized Cu-modified Bi2Se3 catalyst with selenium vacant sites due to the mismatched oxidation states between cations. Compared with pure Bi2Se3, the Cu-modified Bi2Se3 catalyst demonstrated improved catalytic capability for CO2. When the doping ratio of Cu was 8%, the maximum Faraday efficiency of formate reached 65.31% with an overpotential as low as ~500 mV (vs. RHE). Experimental results indicated that the doping of Cu played three roles: (i) improving the adsorption of CO2, (ii) increasing the electrochemical active surface area, and (iii) modifying the electronic structure of Bi2Se3. Moreover, a photoelectrocatalysis system using solar light as energy input was constructed, and a high formate yield of 139.97 μmol h–1 cm–2 was achieved. This study provided a rational Bi2Se3-modification strategy to achieve efficient CO2 conversion.