In Situ Grown Cuboidal MnCo2O4/h Boron Nitride Heterojunction: A Noble Metal-Free Approach Based on Efficient Hole Extraction for Electrochemical Oxygen Evolution Reaction

Rational design of complex spinel oxides directly onto the substrate as a highly stable electrocatalytic anode material for oxygen evolution reaction (OER) is a crucial step to replace a noble metal-based electrocatalyst. Herein, surfactant-free cuboidal MnCo2O4 (C-MCO) was synthesized in situ over FTO by a green and simple synthetic protocol. Stable and good ohmic contact between C-MCO and the substrate ensures efficient transfer of the charge carrier at their interface. Hexagonal boron nitride (h-BN) nanosheets coupled with C-MCO provides a surface for easy deposition of the co-catalyst, making active sites easily available and accessible for enhanced OER activity. The surface-modified C-MCO/h-BN electrode shows a Tafel slope value of 66 mV/dec with an overpotential of 240 mV at a current density of 10 mA/cm(2). C-MCO/h-BN displays similar to 2.8-fold enhancement in turnover frequency compared to its pristine counterpart, with a faradaic yield of 97%. This study can be used for large-scale clean energy production owing to its low-cost, efficient, eco-friendly, and long-term stability of the C-MCO/h-BN electrocatalyst.

Automated summary

This study presents a green and simple method to synthesize surfactant-free cuboidal MnCo2O4 directly onto the substrate. The resulting C-MCO shows stable ohmic contact with the substrate, allowing efficient charge transfer at their interface. Coupling with hexagonal boron nitride (h-BN) nanosheets provides a surface for easy deposition of the co-catalyst, leading to enhanced oxygen evolution reaction (OER) activity. The surface-modified C-MCO/h-BN electrode exhibits good catalytic performance, long-term stability, and potential for large-scale clean energy production.