Nitrogen-doped CdS/TiO2 nanorods heterojunction photoanode for efficient and stable photoelectrochemical water splitting

Abstract

Photoelectrochemical water splitting represents a promising route for converting solar energy into hydrogen, but sluggish reaction kinetics associated with inefficient charge separation and migration, and poor stability limit solar-to-hydrogen conversion. In this work, we develop a N-doped-CdS/TiO₂-nanorods heterojunction photoanode for photoelectrochemical water splitting by anchoring CdS on TiO₂ nanorods followed by nitrogen doping. The light harvesting is significantly enhanced and the charge separation and migration are promoted due to the formed heterojunction and nitrogen doping, which greatly enhances the water oxidation reaction. As a result, the photoelectrochemical cell with the optimized N-doped-CdS/TiO₂-nanorods heterojunction photoanode yields a hydrogen production rate of 42.6 μmol cm⁻² h⁻¹, which is 2.51 times higher than that of the TiO₂-nanorods photoanode. In particular, doping nitrogen atoms into CdS greatly alleviates the photocorrosion problem. Therefore, the newly-developed photoanode exhibits excellent stability under a continuous 10-h running.