High-performance mesoporous hematite photoanodes modified with a conductive water oxidation catalyst, Ni_0.75Fe_0.25O_xH_y, for photoelectrochemical water oxidation are limited by shunting. We present a general method to overcome shunting via the selective electrodeposition of a thin poly(phenylene oxide) (PPO) insulating layer onto the exposed transparent conductive oxide substrate following catalyst deposition.