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.