Key points are not available for this paper at this time.
• A triple-phase interface (TPI) was created on the hydrophobic N-VG-PDMS catalyst. • High Faradaic efficiency and high productivity were obtained for H 2 O 2 production. • Microscopic techniques unveiled a stable TPI microenvironment during the reaction. • The stable TPI simultaneously enhanced gas diffusion and local pH values. Electrochemical oxygen reduction (ORR) through a two-electron (2e − ) pathway offers a green route for on-demand production of hydrogen peroxide (H 2 O 2 ), which is an industrially valuable chemical as well as a renewable energy carrier. Metal-free carbon-based materials have been exploited as promising catalysts for H 2 O 2 generation; however, they often exhibit poor performance with low productivity under acidic conditions. Herein, a nitrogen-doped vertical graphene catalyst is developed with a stable hydrophobic solid–liquid-gas three-phase interface (TPI) enabled by polydimethylsiloxane (PDMS) coating. The catalyst exhibits a high Faradaic efficiency (FE) of ∼ 80 % across a wide potential range from 0 to −0.6 V vs. reversible hydrogen electrode (RHE) at a maximum current density of 140 mA cm −2 , resulting in a remarkably high H 2 O 2 productivity of 21 mol g catalyst −1 h −1 in acid. Furthermore, a high concentration of H 2 O 2 up to 10,500 ppm is obtained with the FE maintained at ∼ 75 %. Confocal laser scanning microscopy (CLSM) and fluorescence lifetime analysis reveal that the hydrophobic TPI increases gas diffusion and local pH value to enhance both activity and selectivity towards H 2 O 2 . This work provides valuable insights into the rational design of metal-free carbon-based catalysts for efficient H 2 O 2 generation.
Zhang et al. (Tue,) studied this question.