Efficient Destruction of Pollutants in Water by a Dual-Reaction-Center Fenton-like Process over Carbon Nitride Compounds-Complexed Cu(II)-CuAlO2

Carbon nitride compounds (CN) complexed with the in-situ-produced Cu(II) on the surface of CuAlO2 substrate (CN-Cu(II)-CuAlO2) is prepared via a surface growth process for the first time and exhibits exceptionally high activity and efficiency for the degradation of the refractory pollutants in water through a Fenton-like process in a wide pH range. The reaction rate for bisphenol A removal is ∼25 times higher than that of the CuAlO2. According to the characterization, Cu(II) generation on the surface of CuAlO2 during the surface growth process results in the marked decrease of the surface oxygen vacancies and the formation of the C–O–Cu bridges between CN and Cu(II)-CuAlO2 in the catalyst. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations demonstrate that the dual reaction centers are produced around the Cu and C sites due to the cation−π interactions through the C–O–Cu bridges in CN-Cu(II)-CuAlO2. During the Fenton-like reactions, the electron-rich center around Cu is responsible for the efficient reduction of H2O2 to •OH, and the electron-poor center around C captures electrons from H2O2 or pollutants and diverts them to the electron-rich area via the C–O–Cu bridge. Thus, the catalyst exhibits excellent catalytic performance for the refractory pollutant degradation. This study can deepen our understanding on the enhanced Fenton reactivity for water purification through functionalizing with organic solid-phase ligands on the catalyst surface.