Solution‐Processed Fabrication of Ni₃S₂‐Based Nanoheterostructure on Silicon Heterojunction Photocathode for Boosting Solar Hydrogen Generation

Silicon heterojunction (SHJ) solar cell is an advanced and mature photovoltaic cell. Development of photoelectrochemical (PEC) water splitting devices for hydrogen fuel production using SHJ solar cells is considered as a promising approach to address energy crisis. To achieve this goal, it is necessary to deposit passivation layer and cocatalyst layer on the photoelectrode. However, the development of low-cost and scalable preparation methods for high-quality passivation and cocatalyst layer continues to be a significant challenge. Herein, an efficient passivation layer and hydrogen evolution reaction (HER) catalyst are successfully fabricated via solution processed methods. To improve the HER activity of Ni₃S₂, a Ni₃S₂-based nanoheterostructure of crystalline Ni₃S₂, Ni, and amorphous Y(OH)₃ is constructed. The optimized photocathode exhibits excellent PEC-HER performance, which achieves a saturated photocurrent of -35.5 mA cm^-2 and an applied bias photon-to-current efficiency (ABPE) of 8.4 ± 0.1% under simulated AM1.5G one-sun illumination and more than 120 h of continuous water splitting. This study paves a way for the design and large-scale manufacturing of cost-efficient SHJ photocathode devices.