A Facile Electrosynthesis of Terephthalate (tp)-Based Metal-Organic Framework, Ni3(OH)2(H2O)2(tp)2 with Superior Catalytic Activity for Hydrogen Evolution Reaction

Utilizing a facile one-step electrodeposition method, several terephthalate (tp)-based MOFs, M-3(OH)(2)(H2O)(2)(tp)(2) (M = Ni, Co or Fe) have been synthesized on Ni foam (NF) or carbon cloth (CC). Among the MOFs, Ni-MOF/NF shows porous nanosheet arrays on NF and exhibits extraordinary hydrogen evolution reaction (HER) catalytic activity with an overpotential (eta(10)) of 60 mV to reach a current density of -10 mA cm(-2), which is superior to Co-MOF/NF (eta(10) = 184 mV) and Fe-MOF/NF (eta(10) = 203 mV), and even comparable to Pt/C (eta(10) = 23 mV), indicating the HER performance is associated with the species of metal ions and the morphology. In addition, it is primarily investigated the formation mechanism of Ni-MOF nanosheet arrays on Ni foam. Furthermore, Ni-MOF/NF can endure 50 h-electrolysis test at -20 mA cm(-2) in alkaline condition. Density functional theory (DFT) calculations identify the active site of Ni3(OH)(2) (H2O)(2)(tp)(2) for HER is the O-site from the coordinated -OH group (Delta G(H)=-0.40 eV) rather than the O-site from the coordinated H2O molecule (Delta G(H) = -1.75 eV).