Metal Silicidation in Conjunction with Dopant Segregation: A Promising Strategy for Fabricating High-Performance Silicon-Based Photoanodes.

Abstract

Silicon (Si)-based Schottky junction photoelectrodes have attracted considerable attention for photoelectrochemical (PEC) water splitting in recent years. To realize highly efficient Si-based Schottky junction photoelectrodes, the critical challenge is to enable the photoelectrodes to not only have a high Schottky barrier height (SBH), by which a high photovoltage can be obtained, but also ensure an efficient charge transport. Here, we propose and demonstrate a strategy to fabricate a high-performance NiSi/n-Si Schottky junction photoanode by metal silicidation in conjunction with dopant segregation (DS). The metal silicidation produces photoanodes with a high-quality NiSi/Si interface without a disordered SiO2 layer, which ensures highly efficient charge transport, and thus a high saturated photocurrent density of 33 mA cm-2 was attained for the photoanode. The subsequent DS gives the photoanodes a high SBH of 0.94 eV through the introduction of electric dipoles at the NiSi/n-Si interface. As a result, a high photovoltage and favorable onset potential of 1.03 V vs RHE was achieved. In addition, the strong alkali corrosion resistance of NiSi also endows the photoanode with a high stability during PEC operation in 1 M KOH. Our work provides a universal strategy to fabricate metal-silicide/Si Schottky junction photoelectrodes for high-performance PEC water splitting.