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

Abstract 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 Ti 3 C 2 T x MXenes are controllably tuned, producing nearly vacancy‐free (Ti 3 C 2 T x ‐V 0 ), single Ti atom vacancy (Ti 3 C 2 T x ‐V S ), or Ti vacancy cluster (Ti 3 C 2 T x ‐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 Ti 3 C 2 T x MXene surfaces, the Ti vacancy clusters in Ti 3 C 2 T x ‐V C create unique lattice carbon ligand environment toward Ru species, which induces ultra‐strong MSI. As a result, compared to Ti 3 C 2 T x ‐V 0 and Ti 3 C 2 T x ‐V S , the Ti 3 C 2 T x ‐V C modulated Ru clusters (Ru@Ti 3 C 2 T x ‐V C ) exhibit the optimized balance of H 2 O 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@Ti 3 C 2 T x ‐V C outperforms commercial Pt/C in terms of overpotential and mass activity. Moreover, as a universal substrate for noble metal catalysts, Ti 3 C 2 T x ‐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.