Electrochemical performance of metal-organic framework MOF(Ni) doped graphene

In the paper, MOF(Ni) and MOF(Ni) complex with graphene MOF(Ni)-GR(w%) are synthesized by solvothermal method. The structure, morphology and elemental composition of samples are analyzed by physical characterization such as SEM, XRD, EDS and XPS. The results show that MOF(Ni) and MOF(Ni)-GR(w%) with high crystallinity and less impurities are successfully synthesized. Different samples are loaded on the electrodes and their electrochemical performances are tested by electrochemical workstation. The results show that doping appropriate graphene in MOF(Ni) can effectively improve the electrochemical catalytic activity of the composites. When the content of graphene is 4%, MOF(Ni)-GR(4%) is of the highest electrochemical catalytic activity, its overpotential is 268 mV, the Tafel slope is 108 mV·dec−1, and it has better electrochemical stability compared with that of Pt/C electrode. The ECSA and EIS of MOF(Ni)-GR(4%) are superior to that of MOF(Ni) in exploring the reasons for enhancing catalytic hydrogen evolution. The reason is that the addition of graphene enhances the conductivity of the composites and reduces the resistance of catalyst transportation. Moreover, the doping of graphene improves the specific surface area of the composites, and provides enough active sites for hydrogen evolution reaction (HER).