Efficient electrochemical water oxidation to hydrogen peroxide over intrinsic carbon defect-rich carbon nanofibers

Abstract

The two-electron water oxidation reaction (2e⁻-WOR) provides a promising route to produce hydrogen peroxide (H₂O₂) from water; but it is currently hampered by low H₂O₂ partial current. Here, intrinsic carbon defect-rich carbon nanofibers are demonstrated to be highly effective for electrochemical 2e⁻-water oxidation. A H₂O₂ current density of 72.6 mA cm⁻² is achieved at 2.9 V vs. RHE which is among the highest values reported for the 2e⁻-WOR. XPS and NEXAFS studies indicate that pentagonal and octagonal ring defects are dominant in the optimal sample. A combination of DFT calculations and a methanol competitive oxidation experiment reveals that ring defects effectively reduce the adsorption strength of OH*, which ultimately promotes the 2e⁻-WOR for valuable H₂O₂ production. Our study makes a helpful attempt in exploring carbon-based materials for efficient 2e⁻-WOR electrocatalysts.