Electrodeposited Heterogeneous Nickel-Based Catalysts on Silicon for Efficient Sunlight-Assisted Water Splitting

Selecting moderate semiconducting materials for photoelectrochemical (PEC) cells is essential to achieve high solar-energy conversion. Despite the advantageous features of silicon, such as earth abundance and narrow band gap, silicon suffers from severe photocorrosion. Here, heterogeneous nickel-based catalysts produced via electrodeposition are investigated to expedite water oxidation and protect the silicon from corrosion. The morphology of the catalysts and their PEC performances are demonstrated in detail. Synergistic Ni nanoparticles (NPs)/Ni(OH)2/n-Si photoanode shows a high photocurrent density of 29.6 mA cm−2 at 1.23 V versus RHE and operates over 140 h. Owing to the insufficient photovoltage generated by a single photoanode, we introduce a perovskite/Si tandem solar cell as a voltage supplier. The fabricated wired tandem device shows a photocurrent density of 9.8 mA cm−2, corresponding to a solar-to-hydrogen (STH) conversion efficiency of 12% without external bias. Our work may present a promising pathway toward a design of spontaneous energy conversion devices.