Balance Effect: A Universal Strategy for Transition Metal Carbides to Enhance Hydrogen Evolution

Hydrogen production from water splitting is one of the most promising approaches to achieve carbon neutrality when high-performance electrocatalysts are ready for the sluggish hydrogen evolution reaction (HER). Although earth-rich and cheap transition metal carbides (TMCs) are potential HER electrocatalysts, their platinum-like electronic structures are severely hampered by their strong binding with hydrogen intermediates (H*). Here, a universal balance effect strategy is proposed, where nitrogen-doped graphene (NG) is introduced to weaken the interactions of TMCs (M = Mo, W, Ti, and V) with H*. Hydrogen binding energies calculated by the density functional theory show that the TMCs coupled with NG appear to be thermo-neutral. Stemming from different work functions of TMCs and NG, partial electrons transfer from TMC to the NG surface, resulting in optimized electronic structures of these electrocatalysts. These optimized electronic structures balance hydrogen adsorption and desorption, leading to synergistically-enhanced HER kinetics. The overpotentials and Tafel slopes of the HER on these TMC@NG electrocatalysts are thus pronouncedly reduced in both acidic and alkaline solutions. This universal strategy provides a novel approach to design effective and stable TMCs as superior HER electrocatalysts. It can be expanded to other electrocatalysts for sustainable hydrogen production in different media.

Automated summary

The universal balance effect strategy proposed in this study introduces nitrogen-doped graphene to weaken the interactions between transition metal carbides and hydrogen intermediates, optimizing the electronic structures and enhancing the kinetics of hydrogen evolution reactions. This approach effectively balances hydrogen adsorption and desorption, leading to synergistically-improved HER performance on the TMC@NG electrocatalysts in both acidic and alkaline solutions.