Hydrogen peroxide (H2O2) is considered as one of the most important green oxidants for a wide range of industries, including wastewater treatment, papermaking and green chemical synthesis. To produce H2O2, an on site method via two electron oxygen reduction reaction (2e-ORR) process has attracted great attention in the fields of green chemistry, chemical engineering, environmental and material science.
Systematic works on highly efficient hydrogen peroxide electrosynthesis with nano-carbon as catalytic materials has been conducted by Institute of Metal Research (IMR) of the Chinese Academy of Sciences.
Recently, a team led by Prof. QI Wei from IMR revealed that the active sites for 2e-ORR could be attributed to carboxyl and carbonyl groups on nanocarbon catalysts via linking the catalytic activity with the accurate chemical composition and structure of nano-carbon materials. The detailed kinetic analysis indicated that the key for the selectivity of 2e/4e-electron product is the adsorption/desorption strength between the active sites of carboxylic groups and H2O2.
Based on these findings about the catalytic process and corresponding structure-function relations, Prof. QI's team, collaborating with the researchers from Peking University and Fuzhou University, developed a novel carbon/surfactant composite electrode for highly selective hydrogen peroxide electrosynthesis.
The system was designed based on the principle of surface engineering and kinetic modulation without changing the surface chemical properties of the carbon catalyst. The important role of the cationic surfactant is to weaken the interactions between carboxyl active sites and H2O2, thus promoting the efficiency and stability for H2O2 electrosynthesis.
In alkaline media, a sustainably high selectivity of peroxide (>96%) across the potential window over 0.8 V for over 10 h could be achieved with the proposed carbon/surfactant system, which outperforms typical noble metal catalysts becoming the new record for H2O2 electrocatalysts.
These findings are expected to highlight the importance of interface design in electrocatalytic reaction systems and to provide mechanistic insight for advancing the potential practical applications of H2O2 electrosynthesis. The studies were published in Journal of Colloid and Interface Sciences and Chem, respectively.
In-situ selectivity modulation by surface-acting cations at the carbon surface (Image by IMR)
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