Mo2TiC2Tx MXene-Supported Ru/Ni–NiO as an Electrocatalyst for the pH-Universal Hydrogen Evolution Reaction

The hydrogen evolution reaction (HER) is a key step in electrocatalytic water splitting, so developing an efficient and robust pH-universal HER electrocatalyst is highly desirable. Here, we report a facile electrodeposition method to synthesize two-dimensional Mo2TiC2Tx MXene-supported Ru nanoclusters immobilized on a Ni–NiO heterostructure (Ru/Ni–NiO/Mo2TiC2Tx) for an enhanced pH-universal HER. As expected, the as-prepared Ru/Ni–NiO/Mo2TiC2Tx demonstrated outstanding HER performance in full-pH range electrolytes, including diminutive overpotentials (η10) of 41, 49, and 76 mV at a current density of 10 mA cm–2, low Tafel slopes of 28, 62, and 68 mV dec–1 in alkaline (1.0 M KOH), acidic (0.5 M H2SO4), and neutral (1.0 M phosphate-buffered solution, pH = 7) electrolytes, respectively. These results outperform the other reported nonprecious-metal electrocatalysts and multimetallic alloy electrocatalysts in the same conditions. Moreover, the operando electrochemical impedance spectroscopy measurements were used to estimate the electrocatalytic HER kinetics of Ru/Ni–NiO/Mo2TiC2Tx, indicating the Mo2TiC2Tx MXene-supported Ni–NiO heterostructure and Ru nanoclusters as excellent functional components in the electrocatalyst and thereby creating a fast charge-transfer kinetics for the HER. This work provided a feasible and convenient avenue to develop a robust and cost-effective pH-universal HER electrocatalyst through an electrochemical method using the Mo2TiC2Tx MXene as supports.