Dispersed Ni Nanoparticles Stabilize Silicon Photoanodes for Efficient and Inexpensive Sunlight-Assisted Water Oxidation

Ni electrodeposited on n -type Si from aqueous solutions in the form of isolated or coalescent nanoparticles (NPs) protects the underlying and partially exposed Si from photocorrosion-induced electrical passivation. Such photoanodes, fabricated without the need for additional protecting layers, a buried junction, and high-vacuum techniques, show a high photovoltage of ∼500 mV for the oxygen evolution reaction (OER), state-of-the-art photocurrents, and faradaic efficiencies > 90% under AM 1.5G illumination conditions at pH 14. Remarkably, these photoelectrodes are stable and can be operated at the light-limited catalytic current from 10 h to more than 40 h in 1 M NaOH. These findings demonstrate that robust and efficient Si-based photoanodes can be produced easily, which opens new opportunities for the implementation of low-cost Si-based monolithic photoelectrochemical cells for efficient solar fuel production.