Edge-Specific Confined Construction of an Interfacial Re–O–Co Bridge for Enhanced Trifunctional Electrocatalysis

The limited abundance of edge sites in transition metal dichalcogenides (TMDCs) has hindered their utilization despite their superior electrocatalytic activity. Here, we propose an edge-oriented modification strategy by precisely confining ultrafine Co₃O₄ nanoclusters on the edges of ReS₂ via interfacial Re–O–Co chemical bridging (Co₃O₄@ReS₂). Unlike conventional surface modifications, this chemical bonding confinement enables selective edge growth, enhancing charge transfer and optimizing the electronic structure. Theoretical and experimental analyses reveal that the interfacial oxygen atoms act as active sites for the hydrogen evolution reaction (HER), facilitating H* adsorption via continuous gap states, while the spin-state transition of Co³⁺ from low-spin to intermediate/high-spin improves oxygen intermediate adsorption, boosting the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). As a result, Co₃O₄@ReS₂ exhibits outstanding trifunctional electrocatalytic performance, achieving low overpotentials of 76 mV for the HER and 260 mV for the OER at 10 mA cm^–2, along with an ORR onset potential of 0.88 V. This study establishes an edge-site engineering approach for TMDC-based electrocatalysts, offering a promising pathway for enhancing energy conversion efficiency.