Promoting the Water‐Reduction Kinetics and Alkali Tolerance of MoNi4 Nanocrystals via a Mo2TiC2Tx Induced Built‐In Electric Field

Abstract Mo‐Ni alloy‐based electrocatalysts are regarded as promising candidates for the hydrogen evolution reaction (HER), despite their vulnerable stability in alkaline solution that hampers further application. Herein, Mo 2 TiC 2 T x MXene, is employed as a support for MoNi 4 alloy nanocrystals (NCs) to fabricate a unique nanoflower‐like MoNi 4 –MX n electrocatalyst. A remarkably strong built‐in electric field is established at the interface of two components, which facilitates the electron transfer from Mo 2 TiC 2 T x to MoNi 4 . Due to the accumulation of electrons at the MoNi 4 sites, the adsorption of the catalytic intermediates and ionic species on MoNi 4 is affected consequently. As a result, the MoNi 4 –MX 10 nanohybrid exhibits the lowest overpotential, even lower than 10% Pt/C catalyst at the current density of 10 mA cm −2 in 1 m KOH solution (122.19 vs 129.07 mV, respectively). Furthermore, a lower Tafel slope of 55.88 mV dec −1 is reported as compared to that of the 10% Pt/C (65.64 mV dec −1 ). Additionally, the MoNi 4 –MX 10 catalyst also displays extraordinary chemical stability in alkaline solution, with an activity loss of only 0.15% per hour over 300 h of operation. This reflects the great potential of using MXene‐based interfacial engineering for the synthesis of a highly efficient and stable electrocatalyst.