▎ 摘　　要

Although nickel-based counter electrodes display good catalytic properties in dye-sensitized solar cells (DSSCs), there are challenges to achieve efficient activity for practical device. Except that, vacancy can effectively regulate electrocatalytic efficiency for the catalytic reactions, which take place on the surface of catalysts. Thereby, the hollow Ni0.85Se nanospheres grown on the reduced graphite oxide (RGO) were designed to attain the composites utilizing a facile hydrothermal strategy, and followed by heating within argon atmosphere at 400 degrees C (NiSe2-400) and 450 degrees C (NiSe2-450), forming NiSe2/RGO composite catalysts with abundant vacancies. Importantly, the resultant NiSe2-400 as counter electrode (CE) exhibits superior electrochemical properties in DSSCs, thus yielding a remarkable photovoltaic performance (8.93%), which may originate from the existence of the appropriate Ni-Se dual vacancies, accelerating the I-3(-) reduction. The work would provide a strategy for the synthesis of other non-noble metal compounds with unconventional dual vacancies to develop the application of DSSCs.