Promoting the Two-Electron Oxygen Reduction Reaction Performance of Carbon Nanospheres by Pore Engineering

Abstract

Electrochemical production of hydrogen peroxide from the two-electron oxygen reduction reaction (ORR) is emerging as a promising method for in situ production of H 2 O 2 . However, carbon materials, one of the most prospective catalysts for the twoelectron ORR, remain not active enough for mass production of H 2 O 2 in acidic or neutral media. Pore channel engineering is an effective strategy to enhance the ORR activity of carbon materials by enlarging the electrochemically accessible surface and facilitating oxygen diffusion. Here, carbon nanospheres with different pore sizes (diameter and depth) were controllably prepared by a soft-template method. The optimized catalyst exhibited an excellent two-electron ORR activity in alkaline and neutral media. Furthermore, electrochemical production of H 2 O 2 in neutral solution with a production rate as high as 1.27 mol g −1 h −1 and a Faraday's efficiency (FE) > 98% were obtained. By combining electrochemical tests with physical characterizations and numerical simulations, the origin of the enhanced ORR performances was elucidated.

Strategies for Sustainable Production of Hydrogen Peroxide via Oxygen Reduction Reaction: From Catalyst Design to Device Setup

“…9 a) [ 146 ]. Recently, Huang et al prepared carbon nanospheres with different pore sizes using phenolic resin spheres as the precursor for studying their ORR performances [ 144 ]. The results showed that catalysts with rich mesopores enabled more accessible contact areas for O 2 and electrolyte ions, thus presenting better 2e – -ORR performance (Fig.…”

“…b Schematic illustration of mesopores for facilitating O 2 transport. Reproduced with permission [ 144 ]. Copyright 2021, American Chemical Society.…”

Research progress of electrocatalysts for the preparation of H2O2 by electrocatalytic oxygen reduction reaction

“…In 1939, Berl 88 first reported the preparation of H 2 O 2 by 2e − ORR on carbon electrodes. Subsequent researchers found that carbon allotropes have different catalytic performances for 2e − ORR, such as graphite, 89 graphene, 33,90 porous carbon, 91 carbon nanospheres, 32 and other applications in electrode catalytic materials were studied. However, the catalytic activity of pure carbon materials is generally not ideal.…”

“…It also has high selectivity and stability for the generation of hydrogen peroxide. Because the pore size significantly affects hydrogen peroxide generation, Huang et al 91 prepared carbon nanospheres with different pore sizes by a soft templating method (Figure 12C,D). The pore size-optimized catalyst exhibits excellent 2e − ORR activity in alkaline and neutral media.…”

A Mild CO2 Etching Method To Tailor the Pore Structure of Platinum-Free Oxygen Reduction Catalysts in Proton Exchange Membrane Fuel Cells

“…Previously, there have been numerous reports on developing strategies to tune the pore structure of the Fe/N/C electrocatalysts with improved ORR activity. − Among them, the template-sacrificing method is one of the most popular strategies. Taking Si or SiO 2 templates as an example, they were first mixed with a carbon precursor, followed by a pyrolysis step, and finally removed by a posttreatment process to build up the pores. , Although the template method can introduce tailorable mesopores, the posttreatment media involved corrosive HF or concentrated KOH and significantly changed the surface structure and composition of the electrocatalysts. ,, These changes may partially offset the efforts to enhance the ORR activity induced by variation of the pore structure.…”