High-Performance and Stable Silicon Photoanode Modified by Crystalline Ni@ Amorphous Co Core-Shell Nanoparticles

Improving the charge separation and transport efficiency at semiconductor-electrolyte interface is critical for high-performance photoelectrochemical (PEC) water-splitting devices. Here, the core-shell-structured Ni@Co nanoislands were electrodeposited onto the surface of n-type Si photoanode to construct a metal-insulator-semiconductor (MIS) structure. We discover that the high-quality interface in Si/SiOx/Ni MIS structure is more efficient for charge extraction and transfer than Si/SiOx/Co. Owing to a slightly higher work function for Co (5.0 eV) than Ni (4.6 eV), the Si/SiOx/Ni@Co exhibits the larger band bending to enhance the charge separation efficiency, while the in-situ formed CoOOH significantly increases the charge injection efficiency due to the decreased oxygen-evolution overpotentials. As a result, the Ni@Co core-shell nanoparticles coupling with n-Si photoanode can afford the PEC performance with an onset potential of 1.02 V versus reversible hydrogen electrode (RHE), saturated current density of 36.7 mA cm(-2), and retain good stability in K-borate buffer solution. This core-shell structure strategy is efficient and easy to achieve the separation of photogenerated carriers and improve the charge injection efficiency to nearly 100 %