Interface Charge Transfer Engineering in NiFe Layered Double Hydroxide-Cs0.32WO3 Heterostructures for Enhanced Oxygen Evolution Reaction

Electrochemical water splitting for hydrogen production is considered a key pathway for achieving sustainable energy conversion. However, the sluggish reaction kinetics of the oxygen evolution reaction (OER) and high overpotentials severely hinder the large-scale application of water electrolysis technology. Nickel-iron layered double hydroxide (NiFe-LDH) has gained attention as a promising non-precious metal OER catalyst due to its abundant active sites and good intrinsic activity. However, its relatively low conductivity and charge transfer efficiency limit the improvement of catalytic performance. Therefore, this study used a simple hydrothermal method to generate a NiFe-LDH/Cs_0.32WO₃ heterojunction composite catalyst, relying on the excellent electronic conductivity of Cs_0.32WO₃ to improve overall charge transfer efficiency. According to electrochemical testing results, the modified NiFe-LDH/Cs_0.32WO₃-20 mg achieved a low overpotential of 349 mV at a current density of 10 mA cm^-2, a Tafel slope of 67.0 mV dec^-1, and a charge transfer resistance of 65.1 Ω, which represent decreases of 39 mV, 23.1%, and 40%, respectively, compared to pure NiFe-LDH. The key to performance improvement lies in the tightly bonded heterojunction interface between Cs_0.32WO₃ and NiFe-LDH. X-ray photoelectron spectroscopy (XPS) shows a distinct interfacial charge transfer phenomenon, with a notable negative shift of the W4f peak (0.85 eV), indicating the directional transfer of electrons from Cs_0.32WO₃ to NiFe-LDH. Under the influence of the built-in electric field within the heterojunction, this interfacial charge redistribution improved the electronic structure of NiFe-LDH, increased the proportion of high-valent metal ions, and significantly enhanced the OER reaction kinetics. This study provides new insights for the preparation of efficient heterojunction electrocatalysts.