Multi-functional Co3O4 embedded carbon nanotube architecture for oxygen evolution reaction and benzoin oxidation

Abstract Multifunctional hybrid nanostructures continue to attract great attention since they offer multiple applications from specific architectures. This paper proposes a simple solid-state protocol to fabricate nitrogen doped carbon nanotubes (CNT) and cobalt oxide embedded with CNT (Co3O4-CNT) for oxygen evolution reaction and benzoin oxidation. The proximity between cobalt and CNT sites amplifies oxygen evolution reaction (OER) and conductivity. Embedded Co3O4-CNT form an integrated architecture, providing efficient and rapid electron/ion transfer rate. Fabricated Co3O4-CNT electrocatalyst exhibited OER activity of 317 mV, which was better than that of pristine Co3O4 electrocatalyst (340 mV) at 10 mA cm−2 current density. Impressively, Co3O4-CNT delivers stable response at low and high currents as well as excellent durability over 25 h. Experimental and analytical results verified that maximal electrocatalytic OER activity can be realized by combining a conductive CNT network and catalytically active sites could be further enhanced by nitrogen doping. Additionally, the Co3O4 embedded with CNT upon exploration as a milder, inexpensive, and eco-friendlier catalyst for air oxidation of 2-hydroxy-1,2-bis(3-methoxyphenyl)ethan-1-one (benzoin), produces 3,3′-dimethoxybenzil in high yield (96%). The Co3O4-CNT was further evaluated the catalytic activities after repetitive recycling processes and demonstrated the high yields without the significant loss in the catalytic activity.