This study focuses on the synthesis of nanoporous NiO nanosheets hybridized with PEDOT:PSS, Cdot and Pt nanoparticles and screening the catalytic activities for the regeneration of iodide ions from triiodide ions in liquid junction photovoltaic devices. Due to a special hexagonal structure of NiO nanosheets, Pt nanoparticles and Cdot are easily immobilized on the surface and walled holes of NiO nanosheets with the size in the range of 2-5 nm. The electrochemical performances indicate the catalytic activity of counter electrodes (CEs) follows the sequence of NiO-Pt > Pt sputtering > NiO-Cdot > NiO-PEDOT:PSS > NiO. Thus, the photovoltaic performances provide the efficiency of 1.73, 5.51, 8.25 and 9.66% for cells with NiO, NiO-PEDOT:PSS, NiO-Cdot and NiO-Pt CEs, respectively, which are compared to the device using the Pt electrode (8.86%). The findings in this work are promising for developing highly efficient Pt-free catalyst materials for CEs of devices.