Electronic-State Modulation of Metallic Co-Assisted Co₇ Fe₃ Alloy Heterostructure for Highly Efficient and Stable...

Manipulating electronic structure of alloy-based electrocatalysts can eagerly regulate its catalytic efficiency and corrosion resistance for water splitting and fundamentally understand the catalytic mechanisms for oxygen/hydrogen evolution reactions (OER/HER). Herein, the metallic Co-assisted Co₇ Fe₃ alloy heterojunction (Co₇ Fe₃ /Co) embeds in a 3D honeycomb-like graphitic carbon is purposely constructed as a bifunctional catalyst for overall water splitting. As-marked Co₇ Fe₃ /Co-600 displays the excellent catalytic activities in alkaline media with low overpotentials of 200 mV for OER and 68 mV for HER at 10 mA cm^-2 . Theoretical calculations reveal the electronic redistribution after coupling Co with Co₇ Fe₃ , which likely forms the electron-rich state over interfaces and the electron-delocalized state at Co₇ Fe₃ alloy. This process changes the d-band center position of Co₇ Fe₃ /Co and optimizes the affinity of catalyst surface to intermediates, thus promoting the intrinsic OER/HER activities. For overall water splitting, the electrolyzer only requires a cell voltage of 1.50 V to achieve 10 mA cm^-2 and dramatically retains 99.1% of original activity after 100 h of continuous operation. This work proposes an insight into modulation of electronic state in alloy/metal heterojunctions and explores a new path to construct more competitive electrocatalysts for overall water splitting.