Synergistic introduction of oxygen vacancy and silver/silver iodide: Realizing deep structure regulation on bismuth oxybromide for robust carbon dioxide reduction and pollutant oxidation

To efficiently solve severe energy shortage and environmental pollution issues, step-scheme (S-scheme) photocatalytic system, as perfect photocatalyst with strong redox ability and swift separation efficiency of carriers, has been considered a feasible tactic. Herein, a novel S-scheme silver/silver iodide/bismuth oxybromide heterojunction with rich oxygen vacancies (OVs) (labeled as Ag/AgI/BiO1-xBr) was in situ fabricated via a simple photodeposition-precipitation method. It was discovered that the obtained Ag/AgI/BiO1-xBr heterojunction with the optimized molar ratio of silver/bismuth (Ag/Bi) at 0.4 presented excellent photocatalytic properties for carbon dioxide (CO2) reduction (2.46 μmol g-1h-1 carbon monoxide (CO) and 1.25 μmol g-1h-1 methane (CH4) generation) and antibiotic tetracycline (TC) removal (96.7%) even in actual waste water or in the presence of electrolytes. The enhanced performance of S-scheme Ag/AgI/BiO1-xBr composite may be ascribed to the collaborative effect of OVs and silver/silver iodide (Ag/AgI), in which OVs acted as the charge transmission bridge for reducing the interface migration resistance of the charge and Ag/AgI served as a cocatalyst for enhancing the separation efficiency of carriers. Furthermore, a feasible photocatalytic mechanism was discussed via density functional theory calculation and in-situ X-ray photoelectron spectroscopy. This work not only demonstrated the synergistic application of OVs transmission bridge and Ag/AgI cocatalyst, but also provided a facile way to design high-efficiency and stable photocatalysts for energy production and environmental remediation.