Phase‐Engineered Dichalcogenides/Fluorine‐Free V ₄ C ₃ T _x (T = OH, O) Heterostructures for pH‐Universal Hydrogen Evolution Reaction

Abstract This research addresses the pH‐dependency limitation in electrocatalytic hydrogen evolution reactions (HER) by creating heterostructures through the chemical bonding between 2D‐dichalcogenides and V ₄ C ₃ T _x (T = OH, O) planes. The one‐step solvothermal synthesis employed in this study constructs a synergistically interacted 1T phase of, e.g., MoS ₂ and V ₄ C ₃ T _x MXene, demonstrating an omnidirectional improvement on catalytic stability, active site exposure, surface area enlargement, electrical conductivity, and hence enhancement of water dissociation activities. Despite the notable progress in creating hydrogen production catalysts with ground breaking performances, a significant gap remains in the availability of catalysts capable of functioning effectively under high current densities. The catalyst 1T MoS ₂ @V ₄ C ₃ T _x shows remarkable activities under the current density of 1000 mA cm ⁻² , which require overpotentials of 16, 24, and 37 mV in 0.5 m H ₂ SO ₄ , 1 m KOH, and 0.1 m PBS electrolytes, respectively at 10 mA cm ⁻² , and exhibits excellent HER performance with small overpotentials of 103.16 and 138 mV to achieve current densities of 500 and 1000 mA cm ⁻² , respectively, with outstanding stability for 1000 cylic voltammetric cycle HER test without degradation in acidic media. Enhanced HER performance has also been observed in other 2D‐dichalcogenides/V ₄ C ₃ T _x heterostructures, providing prospects for phase‐engineered dichalcogenides/fluorine‐free V ₄ C ₃ T _x composites for pH‐universal HER.