We employ a thin Al2O3 interlayer between p-NiOX catalyst/n-Si photoanode interfaces to realize an effective oxygen evolution reaction (OER). The Al2O3 interlayer is used to reduce the interface defect density, enhance the band bending by suppressing the Fermi-level pinning effect, and enhance photovoltage at the catalyst/ semiconductor rectifying junction. Our NiOX/Al2O3/n-Si photoanodes generated a photocurrent of 3.36 mA/cm(2) at the equilibrium potential of OER (E-OER = 1.23 V vs. reversible hydrogen electrode in 1 M NaOH solution) and a solar-to-oxygen conversion efficiency of 0.321%. Moreover, the photoanode showed no sign of decay over 20 h of photoelectrochemical water oxidation. (C) 2015 Elsevier B.V. All rights reserved.