A hierarchical dual-phase photoetching template route to assembling functional layers on Si photoanode with tunable nanostructures for efficient water splitting

Abstract

Surface functionalization is closely associated with the light harvesting and the charge separation, transfer, and injection efficiencies of water-splitting photoelectrode. Here, a dual-phase photoetching template with hierarchical structure, polyphenylsilsequioxane nanopillars and bicontinuous polyphenylsilsequioxane + polystyrene network layer, is patterned on the Si photoanode via a spinodal phase separation mechanism. Controllably photoetching the polymer template allows us to physically deposit functional layers with tunable nanostructures from net to dispersed dot. As a demonstration, the broken Ni/NiOx net modified Si photoanode exhibits a low onset potential of 0.93 VRHE, a high saturated photocurrent density of 40 mA cm−2 and a stability of 50 h in 1.0 M K-borate under AM1.5 G illumination, resulting from the inhomogeneous barrier height driven efficient charge extraction and low light loss by the dispersed surface modification. The proposed dual-phase lithographic template may open a new avenue to easily assemble functional layers on photoelectrodes for efficient solar energy conversion.