Interface-driven kinetic energy barrier modulation in Fe–Mo derivative-supported surface and heterointerface engineered MXene hybrids for alkaline hydrogen evolution

Abstract

Two-dimensional transition metal (TM) derivatives on conductive substrates such as MXenes can offer a promising avenue for accelerating the sluggish electron transfer kinetics associated with the multistep hydrogen evolution reaction (HER). Herein, we design a model electrocatalyst to study the role of the heterointerface in reducing the kinetic energy barrier, E_a, for alkaline HER. A facile and scalable surface-modification strategy for Ti₃C₂T_x (MX) by hydroxyl terminal functionalization followed by hybridizing with Fe–Mo-based derivatives (FeMo) is adopted for FeMo/f-MX hybrid synthesis. This enables the FeMo to hybridize effectively on the surface of Ti₃C₂(OH)_x by forming metal–O bonds. The electrochemical measurements as well as DFT studies reveal enhanced charge transfer kinetics for hybrids, due to the modulation of the electronic structure at the interface. Moreover, the hybrid coatings of FeMo/f-MX exhibit improved HER activity with a drastic decrease in overpotential from 218 mV to 22 mV, as compared to the FeMo coating, when the temperature increases from 20 to 50 °C. Thus, a 47.64% reduction in E_a (97.92 kJ mol⁻¹) is observed for hybrid coatings via the formation of a well-engineered heterointerface through the precise selection of TMs and MXenes. This study provides insights for constructing TM-decorated MXenes to synergistically enhance the electrochemical HER performance by reducing the E_avia surface and interface engineering.