Balancing Volmer Step by Dual-Active Domains for Electrocatalytic H₂ Formation

The reaction kinetics of hydrogen evolution reaction (HER) is primarily determined by balancing the Volmer step in alkaline/neutral media. The bifunctional effect as a proposed strategy divides the reaction process of water dissociation and intermediates ad-/de-sorption. However, sluggish OH^* desorption plagues water re-adsorption, leading to the active domain's poisoning effects. In addition, some active sites may even directly act as spectators and do not participate in the reaction. The activity comparison under approximate nanostructure between bifunctional effect and single-functional-domain is not fully understood.<br/><br/>We adopted a facile three-step strategy to successfully grow MoS₂ on cobalt-containing nitrogen-doped carbon nanotubes (Co-NCNTs), forming obvious dual-active domains. The active domains of Co-NCNTs and MoS₂, with the tuned electronic structure at the heterointerface, trigger the bifunctional effect to balance the Volmer step and boost the catalytic activity. The HER driven by the bifunctional effect could significantly optimize the Gibbs free energy of water dissociation and hydrogen adsorption, resulting in fast reaction kinetics and superior catalytic performance.