The key role of carboxylate ligands in Ru@Ni-MOFs/NF in promoting water dissociation kinetics for effective hydrogen evolution in alkaline media

The [email protected] metal–organic frameworks (MOFs) (M = Ru, Pt, Ir, etc.) have been widely recognized as the outstanding electrocatalysts for hydrogen evolution reaction (HER). However, the mechanism of alkaline HER on [email protected] remains ambiguous. Here, taking [email protected]/NF as an example, its HER synergistic catalytic mechanism has been revealed by in situ FT-IR/Raman spectra, H/D isotope experiments, methanol/SCN− poisoning experiments and DFT calculations. Namely, the carboxylate ligands in [email protected]/NF, apart from regulating the local electronic structure of surface sites, can be used as a Lewis base that exhibits strong affinity toward H2O via intermediate state of –COO-H-OH and subsequently promotes water transfer/activation/dissociation via the form of –COOHOH-Ru with a low kinetic energy barrier. [email protected]/NF shows a low overpotential of 25 mV at 10 mA cm−2 with a small Tafel slope (31 mV dec−1) and excellent stability.