Self-Supporting Nanosheet Electrode for Efficient Oxygen Evolution in a Wide pH Range: Engineering Electronic Structure of Co 3 O 4 by Fe Doping

Abstract

Abstract Developing low-cost and efficient non-precious metal-based electrocatalysts for oxygen evolution reaction (OER) is of great significance for large-scale application of water electrolysis technology. Herein, we present a facile and scalable one-step pyrolysis strategy to fabricate a self-supporting nanosheet electrode involving Fe-doped Co3O4 catalyst (Fe-Co3O4) in-situ grown on carbon paper for efficient and durable OER catalysis in both alkaline and acidic electrolyte. Results show that doping Fe induces the formation of uniform a nanosheet-like morphology with larger specific surface area that facilitates the full exposure of active sites with accessible contact with electrolyte. Electrochemical test results show that the obtained Fe-Co3O4 exhibits superior activity and high stability for OER catalysis in wide pH range, showing the low overpotentials of 263 and 295 mV in 1.0 M KOH and in 0.5 M H2SO4, respectively, outperforming commercial IrO2, and also exhibiting outstanding electrochemical stability up to 420 h in 1.0 M KOH and 15 h in 0.5 M H2SO4 at 10 mA cm− 2. X-ray photoelectron spectroscopy and DFT theoretical calculations reveal that doping Fe modifies the electronic structure of Co3O4 by decreasing the valence state of Co, which upwards d band center of Co site and then promotes adsorption intensity of oxygen intermediates, leading to an enhanced OER activity. Furthermore, doping Fe also increases the cobalt vacancy formation energy in Fe-Co3O4, which inhibits the thermodynamics of Co dissolution, thus improving the structural stability during OER catalysis. This work provides a new insight into the design of high-performance of Co3O4-based non-precious electrocatalysts in both alkaline and acidic electrolyte for large-scale application of water electrolysis.