Built-In Electric Field-Driven Electron Extraction at the BaTiO3/CdS Nanoparticle Interface for Enhanced Photocatalytic H2 Evolution
Yulin Tan, Yanfang He, Ying Yang, Huimin Zhang, Yufang Xie, Chenglin Zhang, Yuan Liu, Mingming Chen, Yefeng Zhu, Dawei CaoAbstract
Nanocatalysts hold broad application prospects for photocatalytic hydrogen evolution. CdS is a visible-light-responsive photocatalyst for hydrogen evolution, but its efficiency is limited by fast electron–hole recombination and insufficient interfacial charge extraction at the nanoscale. Here, a nanoscale type-II BaTiO3/CdS (BTO/CdS) heterojunction was constructed through a chemical bath deposition process to introduce a built-in electric field (BIEF) at the oxide/sulfide interface. The Fermi-level mismatch between BTO and CdS nanostructures induces interfacial charge redistribution, forming a BIEF directed from BTO to CdS. Under light irradiation, this field drives photogenerated electrons from CdS toward BTO, thereby suppressing charge recombination and improving electron utilization for hydrogen evolution. The optimized BTO/CdS composite delivers a hydrogen evolution rate of 5.23 mmol·g–1·h–1 under simulated sunlight, which is 5.5 and 40.2 times higher than those of pure CdS (0.95 mmol·g–1·h–1) and BTO (0.13 mmol·g–1·h–1), respectively. X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), density functional theory (DFT) calculations, and Kelvin probe force microscopy (KPFM) consistently support the BIEF-directed charge transfer pathway. This study clarifies how interfacial electric-field engineering in BTO/CdS nanostructures promotes directional electron extraction and improves CdS-based photocatalytic hydrogen evolution.