Design of Core–Shell‐Structured ZnO/ZnS Hybridized with Graphite‐Like C3N4 for Highly Efficient Photoelectrochemical Water Splitting

Abstract Numerous efforts have been focused on the heterojunction structure for enhancing the electron injection across the interface in application of photocatalysis or photoelectrochemical (PEC) catalysis. The electrochemically deposited ZnO nanorods arrays are sulfurated following hydrothermal reaction to form core–shell heterojunction structure. Furthermore, the graphite‐like C 3 N 4 (g‐C 3 N 4 ) is added into the formed ZnO/ZnS core–shell nanorods during the sulfuration process to get ZnO/ZnS/g‐C 3 N 4 photoanode. The heterojunction structure is characterized via X‐ray diffraction, scanning electron microscope, X‐ray photoelectron spectroscopy, transmission electron microscopy, UV‐vis diffuse‐reflectance spectra, time‐resolved photoluminescence, and Raman. The ZnO/ZnS/g‐C 3 N 4 photoanode yields a photocurrent of ≈0.66 mA cm −2 at 1.23 V versus reversible hydrogen electrode, which is fourfold as large as pure ZnO electrode. The enhanced photocurrent is attributed to the improved separation efficiency of photogenerated electron–hole pairs and accelerated transport of hole to the electrode surface for the oxidation of water. These results suggest substantial potential of metal oxide nanorods arrays with controlled heterojunction construction in PEC water splitting applications.