Carbon Nanotubes Grown on CuO Nanoparticle-Decorated Porous Carbon Microparticles for Water Oxidation

Efficient water splitting is limited by the sluggish oxygen evolution reaction (OER) to a large extent, which inhibits the development of sustainable energy and has attracted widespread attention. In this work, a type of microsized Cu-based metal–organic framework (MOF) of Cu-BTB has been successfully synthesized by a rapid reaction within half an hour. During the subsequent pyrolysis, a large number of N-containing carbon nanotubes (NCNTs) are grown on the entire surface of hierarchically porous MOF-derived nanosized carbons through the introduction of ethylene and ammonia, denoted as NCNT/Cu/C. After oxidation, NCNT-supported nanosized copper oxide embedded in a carbon matrix (NCNT/CuO/C) is finally obtained to show the preserved morphology and high graphitization degree. The high specific surface area and conductivity of NCNTs for NCNT/CuO/C further enable the electrolyte to make better contact with the active materials during the OER. Finally, the optimal nanosized NCNT/CuO/C exhibits a high degree of improvement in OER performance, in which it attains an overpotential of only 369 mV at 10 mA cm^–2, and its Tafel slope is calculated to be 87.4 mV dec^–1, indicating fast reaction kinetics. The demonstrated work proves that the method of doping NCNTs with nanosized copper oxides can effectively enhance the efficacy of water oxidation, which can be further used in future energy applications.