Development of Dual-Nanoarchitecture Photoanodes Based on Microwave-Assisted ZnS(en)_0.5 Nanoplates for Photoelectrochemical Hydrogen Generation

In this study, a microwave-assisted (MW) synthesis approach is used to develop an inorganic–organic ZnS­(en)_0.5 nanoplate (NP) on a Zn foil substrate. Morphological studies revealed that the growth of the ZnS­(en)_0.5 NP on Zn foil increased with prolonged MW irradiation time. Additionally, X-ray diffraction analysis, fourier transform infrared spectroscopy, and transmission electron microscopy unveiled the structural properties of the inorganic–organic hybrid ZnS­(en)_0.5 NP electrode to investigate the morphological evolution and the growth mechanism. Furthermore, the fabricated inorganic–organic ZnS­(en)_0.5 NP was exposed to Cd²⁺-ion exchange at different temperatures (140, 160, and 180 °C for 6 h) to improve its light absorption and photoelectrochemical properties. The Zn_1–xCd_xS porous nanoplate (PNP)/ZnO nanorod (NR)­160 photoanode (160 °C for 6 h) exhibited a high photocurrent density of 4.81 mA·cm^–2 at 0.5 V vs RHE. The optimized photoanode also yielded a hydrogen evolution rate of 89.76 μmol·cm^–2 under 3 h of solar light illumination. Thus, the formation of the Zn_1–xCd_xS porous structure and the growth of the ZnO NR during Cd²⁺-ion exchange enhanced the photocurrent density and, consequently, prolonged the recombination lifespan of the Zn_1–xCd_xS PNP/ZnO NR160 photoanode.