Fluorine-doped CuBi2O4 nanorod arrays for enhanced photoelectrochemical oxygen reduction reaction toward H2O2 production

CuBi2O4 (CBO) semiconductor composed of low cost and environmentally friendly Cu, Bi, and O elements possesses relatively narrow band gap, appropriate energy band position, and very positive photocurrent onset potential, which make it promising for photoelectrochemical (PEC) O2 reduction reaction (ORR). However, low separation and transfer efficiency of photogenerated carriers and poor product selectivity limit its further application in PEC ORR toward H2O2 production. In this work, we report F− ions doped CuBi2O4 (F-CBO) nanorod arrays with enhanced PEC ORR performance for H2O2 generation. PEC ORR activity of CBO nanorod arrays was obviously enhanced through decreasing the sizes of nanorods. Furthermore, the doping of F− ions into CBO lattice promoted the separation and transfer of photogenerated carriers and significantly improved the selectivity of ORR toward H2O2 path. As a result, 0.85 mmol/L of H2O2 could be achieved on the F-CBO photocathode within 45 min under simulated AM1.5G sunlight illumination (100 mW cm−2), which is 2.8 times higher than that obtained on the pristine counterpart. The roles of fluorine doping were revealed based on experimental results and density functional theory (DFT) calculations. The combination of morphology and surface doping engineering provides a new strategy for designing highly efficient photocathod for PEC ORR to H2O2 production.