Carboxyl functionalized double-walled carbon nanotubes for oxygen evolution reaction

Abstract

The designment and development of high-performance electrocatalysts for oxygen evolution reaction (OER) have considerable impact on research. Recently, significant progress has been made in the preparation of effective carbon-based OER catalysts. The active sites increase after the defects are introduced, but the structure of the carbon nanotubes would be destroyed and its electrical conductivity become worse. Double-walled carbon nanotubes (DWNTs) have a coaxial structure that the inner tube can provide a continuous conductive path and the functionalized outer wall can interact with the external environment, which has potential catalytic capacity. However, there is little research focus on DWNTs for OER catalysis. Herein, we develop the plasma etching strategy as an effective method for obtaining carboxyl functionalized DWNTs (denoted as P-DWNTs-x). P-DWNTs-3 exhibits a small overpotential of 279 mV at current density of 10 mA cm−2 in 1.0 M KOH, superior enough to be compared with RuO2. Moreover, the catalytic mechanism of OER procedure is elucidated by involving carboxyl groups in this process as the active site. This work highlights the coaxial structure of DWNTs, and the mechanism of organic functional groups participating in the OER process, which is expected to open a new possibility for the development of carbon-based for electrocatalysis.