One-pot fabrication of mesoporous g-C3N4/NiS co-catalyst counter electrodes for quantum-dot-sensitized solar cells

The nickel sulfide (NiS) nanoparticles were anchored on the mesoporous graphitic carbon nitride (g-C 3 N 4 ) by one-pot calcination with sulfur powder as sulfur source and pore-forming agent. It is the first attempt to use the g-C 3 N 4 /NiS as a counter electrode (CE) for quantum-dot-sensitized solar cells. The g-C 3 N 4 /NiS co-catalyst based on 0.74 wt% NiS loading for S n 2− reduction obtained a low interface charge transfer resistance ( R ct ) of 1.08 Ω. The power conversion efficiency of the QDSSC assembled with ZnSe/CdS/CdSe/ZnSe-sensitized TiO 2 photoanode and g-C 3 N 4 /NiS CE is up to 5.64%, which is 3.05 times as high as that of pure g-C 3 N 4 CE. The enhancement of cell efficiency is attributed to the synergistic effects of excellent morphology of g-C 3 N 4 and its co-catalysis with NiS nanoparticles. The mesoporous architecture contributes a large specific surface area and fast electrolyte transfer channels, and the coupling of g-C 3 N 4 with NiS promotes the transfer of charge between the interface g-C 3 N 4 /NiS and electrolytes. The presented strategy for fabricating mesoporous architecture with g-C 3 N 4 /NiS uses low-cost raw materials and a simple preparation method, which provides a feasible route to enhance the electrocatalytic activity of g-C 3 N 4 .