Modulating coal-derived carbon toward electrocatalytic generation of hydroxyl radicals for organic contaminant removal

The three-electron oxygen reduction reaction (3e- ORR), which consists of the electrochemical production of hydrogen peroxide (H2O2) and the subsequent activation, allows for the facile generation of hydroxyl radicals (OH) for environmental remediation. However, the current understanding on designing the corresponding electrocatalyst is not adequate. Herein, carbon-based electrocatalysts are prepared using bituminous coal as the raw material to obtain a high content of oxygen, which is crucial for H2O2 production, and the oxygen-containing functional groups (OFGs) in the electrocatalyst are modulated to improve the OH production efficiency. Experimental and calculation results demonstrate that C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 O groups serve as active sites for not only H2O2 formation but also the activation of H2O2 to produce OH, while H2O2 desorption and H2O2 activation are more favorable at COOH and CO sites, respectively. Therefore, after deliberately removing COOH groups from the coal-derived carbon surface, the OH production efficiency is increased, leading to the fast removal of organic dyes from water. Our results demonstrate the significance of modulating the surface OFGs on the carbon-based electrocatalyst toward efficient OH production from the 3e- ORR, which provides a green and sustainable route toward organic contaminant removal from water. Coal-derived carbon catalysts are modulated for producing hydroxyl radicals from oxygen gas to remove organic contaminants from water, and the roles of oxygen containing groups are explored, which would contribute to a greener society.