2D MOF Structure Tuning Atomic Ru Sites for Efficient and Robust Proton Exchange Membrane Water Electrolysis

Developing cost-effective ruthenium (Ru)-based HER electrocatalysts as alternatives to commercial Pt/C is crucial for the advancement of proton exchange membrane water electrolysis (PEMWE). However, the strong hydrogen adsorption of Ru-based catalysts restricts its activity. Herein, a strategy is reported to tune the electronic structure and improve mass transfer by implanting Ru atoms onto the (002) facet of two-dimensional zeolitic imidazolate framework-67 (Ru@LZIF₍₀₀₂₎) to optimize the d-band center (ε_d) of Ru and the hydrogen spillover behavior. Benefiting from the ultrathin nanosheet structure and optimized ε_d of Ru, the over-strong H adsorption energy is weakened and the electron/mass transfer is facilitated. Ru@LZIF₍₀₀₂₎ exhibits an overpotential of 9.2 mV at 10 mA cm^-2 and a long-lasting stability of 35 days at 100 mA cm^-2. The mass activity and price activity of Ru@LZIF₍₀₀₂₎ is 2.9 and 14.7 times higher than Pt/C, respectively. More impressively, Ru@LZIF₍₀₀₂₎ delivers a cell voltage of 2.01 V at a high current density of 4 A cm^-2 in PEMWE. The excellent long-term durability of 1200 hours operating at 4 A cm^-2 with an ultralow decay rate of 7.5 × 10^-3 mV h^-1 has been achieved, making it promising as a cost-effective alternative to Pt/C catalyst for PEMWE applications.