Efficient oxygen evolution reaction on RuO₂nanoparticles decorated onion-like carbon (OLC)

Oxygen evolution reaction (OER) is an important half-cell reaction of the electrical water splitting, for its high overpotential associated with sluggish OER kinetics. Therefore, it is critical to develop highly active and durable electrocatalysts to reduce the overpotential. Herein, ultra-small RuO₂nanoparticles (NPs) supported on onion-like carbon (OLC) and carbon nanotube (CNT) are successfully synthesized by means of wet impregnation combined with annealing treatment, respectively. The microstructure characterization results showed OLC perfect graphitic carbon layer structure, and the RuO₂NPs supported on the OLC possess larger particle size compared with the RuO₂NPs supported on the CNT. Moreover, the electronic structure of Ru in RuO₂/OLC was also optimized by the OLC support to be beneficial for the OER. The OER performance of the catalysts were investigated in 1 M KOH solution. The results show RuO₂/OLC has a comparable OER activity to the commercial RuO₂, but a significantly higher mass activity than the commercial RuO₂. When compared with the RuO₂/CNT, RuO₂/OLC not only exhibits lower overpotential and Tafel slop, but also owns more active sites and higher TOF value, indicating the OLC support improved the OER activity of RuO₂/OLC. Moreover, RuO₂/OLC showed a superior stability compared with RuO₂/CNT, which can be attributed to the excellent electrochemical oxidation-resistance of the OLC.