Fabrication and photoelectrochemical properties of silicon/nickel oxide core/shell nanowire arrays†
A photoelectrochemical (PEC) cell made of a silicon nanowire array coated with a thin nickel oxide (NiOx) shell layer for solar water oxidation is presented. The silicon/NiOx core/shell nanowire photoanodes are fabricated by a simple and scalable one-step galvanic displacement reaction and thermal annealing. The conformal NiOx shell layer functions as an oxygen evolution catalyst to reduce the onset potential as well as a protection layer against corrosion. It was found that about 30 nanometer thick NiOx film coated p-type silicon nanowire arrays exhibited efficient water oxidation activity with stability for more than 48 h in aqueous Na2SO4 solution (pH ∼ 7). The scalability of this approach is promising for the fabrication of Si-based photoelectrodes.