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.

Automated summary

In this study, cation vacancy structures in Ti3C2Tx MXenes were controllably tuned through a facile HF etching method, resulting in vacancy-free (Ti3C2Tx-V-0), single Ti atom vacancy (Ti3C2Tx-V-S), or Ti vacancy cluster (Ti3C2Tx-V-C) engineered MXenes. Ruthenium atomic clusters successfully anchored on all MXene substrates, and the Ti3C2Tx-V-C modulated Ru clusters (Ru@Ti3C2Tx-V-C) exhibited superior electrocatalytic performance in the alkaline hydrogen evolution reaction (HER) compared to other MXenes.