Cation Vacancy Clusters in Ti3C2Tx MXene Induce Ultra-Strong Interaction with Noble Metal Clusters for Efficient Electrocatalytic Hydrogen Evolution

MXenes are promising substrates for supported noble metal electrocatalysts. Yet, it is a significant challenge to modulate the metal-support interaction (MSI) for enhancing catalytic performance. Herein, employing a facile HF etching method, the cation vacancy structures in Ti3C2Tx MXenes are controllably tuned, producing nearly vacancy-free (Ti3C2Tx-V-0), single Ti atom vacancy (Ti3C2Tx-V-S), or Ti vacancy cluster (Ti3C2Tx-V-C) engineered MXenes. Ruthenium atomic clusters, as a model catalyst, successfully anchor on all MXene substrates. Different from the terminal -O/-F coordination groups on routine Ti3C2Tx MXene surfaces, the Ti vacancy clusters in Ti3C2Tx-V-C create unique lattice carbon ligand environment toward Ru species, which induces ultra-strong MSI. As a result, compared to Ti3C2Tx-V-0 and Ti3C2Tx-V-S, the Ti3C2Tx-V-C modulated Ru clusters (Ru@Ti3C2Tx-V-C) exhibit the optimized balance of H2O adsorption/dissociation and OH/H desorption, thereby delivering superior electrocatalytic performance in the alkaline hydrogen evolution reaction (HER). Within the wide range from laboratory-level (90 mA cm(-2)) to industrial-level (1.5 A cm(-2)) current density, Ru@Ti3C2Tx-V-C outperforms commercial Pt/C in terms of overpotential and mass activity. Moreover, as a universal substrate for noble metal catalysts, Ti3C2Tx-V-C can also anchor Ir/Pt/Rh atomic clusters and enable excellent HER catalytic activity. This work expands the scope of the MSI between MXene and noble metal catalysts.