The present work reports a simple Ni(CH3COO)(2) post-treatment method, meanwhile represents a series of characterizations of bare and post-treated NiO photocathodes. The investigation enlightens the mechanisms responsible for NiO surface changes and its effects on the charge density, band-edge shifts, hole injection efficiency, interface recombination, transport, collection efficiency, and as the result influence on the photovoltaic devices' performance. The primary results demonstrate that Ni(CH3COO)(2) post-treatment can offer an effective way of decreasing surface NiO(OH) structure, resulting in diminishing the hole recombination, increasing the charge collection efficiency, and leading to 31.3 % increased photovoltaic performance.