Highly efficient hydrogen peroxide electrosynthesis on oxidized carbon nanotubes by thermally activated-persulfate

Electrochemical synthesis of hydrogen peroxide (H₂O₂) through two-electron oxygen reduction represents an attractive alternative for on-site H₂O₂ generation. Here, we develop a facile thermally activated-persulfate approach to obtain oxidized carbon nanotubes (O-CNTs-x, x represents oxidation time) with enhanced H₂O₂ electrosynthesis performance. Electrochemical studies have demonstrated that the optimized O-CNTs-6 (i.e., oxidation time is 6 h) could deliver a sustained high selectivity of around 92% for H₂O₂ over a wide voltage window in 0.1 mol/L KOH and a high H₂O₂ production rate of 296.84 mmol/L g^-1 _cat h^-1. Compared with pristine CNTs, the enhanced catalytic activity primarily stems from the newly-generated oxygen-containing functional groups and some defects created on the surface of O-CNTs-x. Importantly, the proposed oxidation process is proved to be valid for promoting H₂O₂ electrosynthesis performance of the Ketjen black. This study provides an universal oxidation method to obtain highly active carbon-based catalysts and initiates new opportunities for the exploration of high-performance electrosynthesis H₂O₂ catalysts.