An S-scheme heterojunction engineered with spatially separated dual active groups for simultaneously photocatalytic CO2 reduction and ciprofloxacin oxidation

Solar-driven CO₂ conversion and pollutant removal with an S-scheme heterojunction provides promising approach to alleviate energy shortage and environmental crisis, yet the comprehensive regulation of the charge separation and the activation sites of reactant molecules remains challenging. Herein, a dual-active groups regulated S-scheme heterojunction for hydroxy-regulated BiOBr modified amino-functionalized g-C₃N₄ (labeled as HBOB/ACN) was designed by spatially separated dual sites with hydroxyl group (OH) and amino group (NH₂) toward simultaneously photocatalytic CO₂ reduction and ciprofloxacin (CIP) oxidation. The optimized HBOB/ACN delivers around 2.74-fold CO yield rate and 1.61-times CIP removal rate in comparison to BiOBr/g-C₃N₄ (BOB/CN) without surface groups, which chiefly ascribed the synergistic effect of OH and NH₂ group. A series of experiments and theoretical calculation unveiled that the OH and NH₂ group trapped holes and electrons to participate in CIP oxidation and CO₂ reduction, respectively. Besides, dual-functional coupled reaction system realized the complete utilization of carriers. This work affords deep insights for dual-group modified S-scheme heterojunctions with redox active sites toward dual-functional coupled reaction system for environment purification and solar fuel production.