Z‐Scheme Heterojunction of Hierarchical Cu <sub>2</sub> S/CdIn <sub>2</sub> S <sub>4</sub> Hollow Cubes to Boost Photoelectrochemical Performance
Si Zhang, Jiahui Sun, Huangxian Ju
Abstract
Abstract The exaltation of light‐harvesting efficiency and the inhibition of fast charge recombination are pivotal to the improvement of photoelectrochemical (PEC) performance. Herein, a direct Z‐scheme heterojunction is designed of Cu 2 S/CdIn 2 S 4 by in situ growth of CdIn 2 S 4 nanosheets on the surface of hollow CuS cubes and then annealing at 400 °C. The constructed Z‐scheme heterojunction is demonstrated with electron paramagnetic resonance and redox couple ( p ‐nitrophenol/ p ‐aminophenol) measurements. Under illumination, it shows the photocurrent 6 times larger than that of hollow Cu 2 S cubes, and affords outstanding PEC performance over the known Cu 2 S and CdIn 2 S 4 ‐based photocatalysts. X‐ray photoelectron spectroscopy and density functional theory results demonstrate a strong internal electric field formed in Cu 2 S/CdIn 2 S 4 Z‐scheme heterojunction, which accelerates the Z‐scheme charge migration, thereby promoting electron–hole separation and enhancing their utilization efficiency. Moreover, the hollow structure of Cu 2 S is conducive to shortening the charge transport distance and improving light‐harvesting capability. In proof‐of‐concept PEC application, a PEC detection method for miRNA‐141 based on the sensitivity of benzo‐4‐chloro‐hexadienone to light absorption on Cu 2 S/CdIn 2 S 4 modified electrode is developed with good selectivity and a limit of detection of 32 aM. This work provides a simple approach for designing photoactive materials with highly efficient PEC performance.