Co-modified Ni/N-doped carbon as electrocatalysts for HER and OER

Ni,Co-MOFs have been synthetized by a simple hydrothermal method. Subsequently, Co,Ni/N-doped porous carbon have been prepared by pyrolysis method using the Ni,Co-MOFs as precursor. The results show that the samples present high degree of graphitization. The Co-1–Ni-0.5/NC possesses the largest BET surface area (94.73 m2/g) and pore volume (0.456 cm3/g). The Co-1–Ni-0.5/NC presents the smallest HER overpotential (179 mV) and the best electrocatalytic activity for HER. The Co-0.5–Ni-0.5/NC and Co-1–Ni-0.5/NC have the relatively low overpotential for OER, which are about 348 mV and 383 mV, respectively. The smallest Tafel slope value indicates that Co-1–Ni-0.5/NC presents the best electrocatalytic reactive kinetics. Excellent electrocatalytic performance may be attributed to the more active sites, the higher specific surface area and mesopores as well as the lower charge-transfer resistance. The excellent HER and OER of Co-1–Ni-0.5/NC make its potential to be used on overall water splitting.