Heterointerface engineering of 1D@2D CoSe2@CoFe-LDH for bifunctional water electrolysis via synergistic geometric and electronic modulation

Abstract

Developing highly active and durable bifunctional electrocatalysts for sustainable water electrolysis remains critical yet challenging. Heterostructure engineering through interfacial electronic modulation has emerged as an effective strategy to enhance electrocatalytic performance. In this work, we fabricate a hierarchical 1D@2D heterostructure through epitaxial growth of conductive CoSe₂ nanoneedle arrays on CoFe-layered double hydroxide (CoFe-LDH) nanosheets, creating a CoSe₂@CoFe-LDH hybrid catalyst. The CoSe₂@CoFe-LDH catalyst synergistically combines the advantages of 1D@2D heterostructures and optimized electronic states induced by charge redistribution at the heterointerface, which not only provides abundant accessible active sites and facilitates mass/charge transport but also creates dual active centers with the high-valent Fe species favorable for the oxygen evolution reaction (OER) and the low-valent Co species advantageous for the hydrogen evolution reaction (HER). The optimized CoSe₂@CoFe-LDH demonstrates exceptional bifunctional performance, requiring overpotentials of only 273 mV for the OER at 100 mA cm⁻² and 100 mV for the HER at 10 mA cm⁻² in alkaline media. When deployed as both the anode and the cathode in a two-electrode electrolyzer, the system requires only 1.63 V to reach 10 mA cm⁻². This work provides new insights into heterostructure design through interfacial charge engineering for advanced electrocatalytic systems.