Regulating the Charge Migration in CuInSe₂ /N-Doped Carbon Nanorod Arrays via Interfacial Engineering for Boosting Photoelectrochemical Water Splitting

Regulating the charge migration and separation in photoactive materials is a great challenge for developing photoelectrochemical (PEC) applications. Herein, inspired by capacitors, well-defined CuInSe₂ /N-doped carbon (CISe/N-C) nanorod arrays are synthesized by Cu/In-metal organic frame-derived method. Like the charge process of capacitor, the N-doped carbon can capture the photogenerated electron of CISe, and the strong interfacial coupling between CISe and N-doped carbon can modulate the charge migration and separation. The optimized the CISe/N-C photoanode achieves a maximum photocurrent of 4.28 mA cm^-2 at 1.23 V versus reversible hydrogen electrode (RHE) in neutral electrolyte solution under AM 1.5 G simulated sunlight (100 mW cm^-2 ), which is 8.4 times higher than that of the CuInSe₂ photoanode (0.51 mA cm^-2 ). And a benefit of the strong electronic coupling between CISe and N-doped carbon, the charge transfer rate is increased to 1.3-13 times higher than that of CISe in the range of 0.6-1.1 V versus RHE. The interfacial coupling effects on modulating the carrier transfer dynamics are investigated by Kelvin probe force microscopy analysis and density functional theory calculation. This work provides new insights into bulk phase carrier modulation to improve the performance of photoanode for PEC water splitting.