Selective H2O2 conversion to hydroxyl radicals in electron-rich area of hydroxylated C-g-C3N4/CuCo-Al2O3
The Fenton reaction has been explored extensively in different fields due to the generation of hydroxyl radicals (•OH). However, the reaction requires a strong acid condition and excess consumption of H2O2, which impede its widespread application. Here, we report that two •OH radicals were formed by one H2O2 reacting with a type of nano-composite OH-CCN/CuCo-Al2O3 under nearly neutral conditions. The nano-composite was achieved by the co-incorporated Cu and Co in γ-Al2O3, and the sequential complex formation of σ-type Cu-O-C linker between the surface Cu and the hydroxyl group of the tri-s-triazine ring in C-g-C3N4. From electron paramagnetic resonance spectra and density functional theory simulations, it was verified that an electron-rich area around Cu occurred due to the Cu-π interaction and the different electronegativity of Cu with Co and Al in OH-CCN/CuCo-Al2O3, which reacted with H2O2, resulting in two electron transfer processes. One process is from the electron-rich Cu center to H2O2 to form •OH, the other is from H2O to the N atom of OH-CCN to produce •OH. The catalyst shows extremely high activity for the degradation of various refractory organic pollutants in water under mild conditions with a high utilization efficiency of H2O2 (~90%). Our findings confirm that the construction of an electron-rich area is essential for overcoming the limitations of the classical Fenton process for environmental remediation and other applications.