Empowering green sustainable technologies: Frontier synthesis of oxygen vacancy-modified cobalt oxide

Abstract

The electrocatalytic hydrogen production and supercapacitor technologies have positive impacts on the environment, promoting the production and utilization of clean and renewable energy sources, thus facilitating the reduction of greenhouse gas emissions. Among them, cobalt oxide (Co3O4) has emerged as an ideal choice for electrode materials in these technologies due to its low toxicity, affordability, and significant theoretical capacity. Nevertheless, practical applications are restricted by its low conductivity and sluggish reaction kinetics. Addressing these challenges, this study introduces a pioneering approach: the synthesis of oxygen vacancy-modified Co3O4/Co/NC small-sized nanoflower composite, which combines the advantages of abundant oxygen vacancies, small size effects, and nitrogen-doped porous carbon. The optimized Co3O4/Co/NC small-sized nanoflower exhibits high porosity and excellent conductivity, providing numerous active sites and effectively enhancing the ion and electron transport rates. As a consequence, optimized Co3O4/Co/NC shows a low Tafel slope and overpotential, highlighting its potential for catalytic application. Moreover, as an electrode for supercapacitors, optimized Co3O4/Co/NC demonstrates excellent long-term stability, maintaining 94.7% of its capacitance even after 5000 charge-discharge cycles. Additionally, it showed a significant specific capacity of 251.4 mAh g−1 when tested at 1 A g−1. In addition to addressing the pressing challenges associated with traditional Co3O4 electrodes, this work opens up exciting avenues for designing and fabricating transition metal oxide-based materials with unprecedented electrochemical performance.