Silicon photoanodes partially covered by Ni@Fe core-shell particles with in situ formed gradient-enhanced junction electric field for photoelectrochemical water oxidation

Light harvesting and charge separation-injection efficiency in the photoanode-electrolyte interface region are two important factors for efficient solar energy conversion. Herein, core-shell-structured Ni@Fe nanoparticles were electrodeposited on the surface of an n-type Si photoanode and in situ electrochemically oxidized to Ni@Fe@FeOOH. The dispersed core-shell-structured islands with a gradient-enhanced work function are beneficial for maximizing the light absorption, the charge extraction, and the charge injection. As a result, the n-Si/SiOx/Ni@Fe photoanode exhibited a low oxygen evolution reaction onset potential of 1.02 VRHE, a high saturated current density of 36.7 mA, cm−2, a charge injection efficiency to nearly 100%, and a stable activity for 83 h in K-borate buffer solution with pH = 9 under AM1.5 G simulated sunlight irradiation at 1 sun.Light harvesting and charge separation-injection efficiency in the photoanode-electrolyte interface region are two important factors for efficient solar energy conversion. Herein, core-shell-structured Ni@Fe nanoparticles were electrodeposited on the surface of an n-type Si photoanode and in situ electrochemically oxidized to Ni@Fe@FeOOH. The dispersed core-shell-structured islands with a gradient-enhanced work function are beneficial for maximizing the light absorption, the charge extraction, and the charge injection. As a result, the n-Si/SiOx/Ni@Fe photoanode exhibited a low oxygen evolution reaction onset potential of 1.02 VRHE, a high saturated current density of 36.7 mA, cm−2, a charge injection efficiency to nearly 100%, and a stable activity for 83 h in K-borate buffer solution with pH = 9 under AM1.5 G simulated sunlight irradiation at 1 sun.