Orange peel derived activated carbon supported Ni–Co3O4 as an efficient electrocatalyst for oxygen evolution and reduction reaction in alkaline media

Abstract

This study focuses on the development of a cost-effective electrocatalyst with excellent activity and stability for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR), which is crucial for water electrolysis and fuel cell technologies. Waste orange peel is utilized as a carbon precursor to synthesize biomass-derived activated carbon (OPAC) with a unique three-dimensional sheet-like microstructure. Subsequently, a simple hydrothermal method is employed to modify the OPAC by introducing Ni-doped Co3O4, leading to the formation of a Ni–Co3O4/OPAC hybrid. We propose the Ni–Co3O4/OPAC hybrid as a highly efficient bifunctional electrocatalyst for both OER and ORR. Co3O4/OPAC and Co3O4 catalysts are also prepared for comparison. Remarkably, the Ni–Co3O4/OPAC hybrid exhibits significantly enhanced OER activity compared to Co3O4/OPAC and Co3O4 catalysts. It demonstrates a lower overpotential of 360 mV and a lower Tafel slope of 55.47 mV/dec, indicative of more efficient electrochemical performance. Moreover, in the ORR analysis, the Ni–Co3O4/OPAC hybrid displays a two-step pathway and achieves a higher ORR limiting current density compared to the Co3O4/OPAC and Co3O4 catalysts. These results highlight the synergistic effects of Ni and Co species, along with the unique properties of the OPAC support, which contribute to the enhanced activity, stability, and electron transfer characteristics of the Ni–Co3O4/OPAC hybrid. Furthermore, the improved electrical conductivity of the Ni–Co3O4/OPAC hybrid makes it a promising candidate for applications in metal-air batteries and other energy conversion devices. The utilization of waste orange peel as a carbon precursor and the facile synthesis method demonstrate the potential for cost-effective and sustainable electrocatalyst production. Overall, the Ni–Co3O4/OPAC hybrid represents a significant advancement in electrocatalyst design and holds promise for advancing the field of energy conversion and storage.