Efficient Way To Assemble CdS Nanorose-Decorated CdSe-Tetrakaidecahedron Heterojunction Photoanodes for High-Photoelectrochemical Performance

The 3D structure assembly of CdSe tetrakaidecahedron (TDH) modified with the oxygenated CdS nanorose (NR) structure plays a crucial role in the photoelectrochemical (PEC) performance because of its advanced morphological, intrinsic optical, and electronic properties. The CdS NR-decorated CdSe-TDH nanostructure is demonstrated on cadmium substrates for the first time, exhibiting a greatly enhanced photocurrent density than the CdSe-TDH nanostructure. A CdSe-TDH photoanode solvothermally synthesized at 160 °C showed excellent PEC performance (2.78 mA·cm^–2) under 1 sun illumination. In addition, the photocorrosion of CdSe-TDH photoanodes was systematically investigated, and PEC stability has been improved owing to the formation of nanobuilding blocks between the CdSe-TDH and the CdS NR structures. A set of CdS NR-decorated CdSe-TDH heterojunction at different hydrothermal times was examined and was found to be sensitive to the morphology. X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analyses of the CdS NR/CdSe-TDH-4h heterojunction photoanodes confirm the formation of the CdSO₃ layer on CdS NR/CdSe-TDH-4h. In this study, CdS NR/CdSe-TDH-4h heterojunction exhibits the optimal photocurrent density of 4.2 mA·cm^–2, and it is attributed to a quantum size effect and formation of the porous structure caused by the slow elimination of ethylenediamine (en) during the PEC measurement under solar light irradiation. Furthermore, the charge transport mechanism in CdSO₃/CdS NR/CdSe-TDH-4h heterojunction photoanodes has been discussed. We believe that this shape-control strategy provides guidance to overcome the hole-transfer limitation and offers a new opportunity for designing a new type of nanostructure photoanodes which can be applied to photovoltaic devices.