Theoretical guidance for the construction of electron-rich reaction microcenters on C–O–Fe bridges for enhanced Fenton-like degradation of tetracycline hydrochloride

Abstract

The construction of dual electron reaction centers is an attractive strategy to accelerate the rate-limiting step in Fenton-like catalyst. In this work, we constructed the dual electron reaction centers and electron transport path over C–O–Fe bridges connected by graphene oxide (GO) and Fe3O4 through density functional theory (DFT). The calculations show that there is a strong interaction of C–O–Fe between GO and Fe3O4, and electrons around C would transfer to Fe along C–O–Fe linkages and the electron-rich reaction microcenters are generated around Fe. Based on it, Fenton-like catalyst of ultra-small Fe3O4 (less than 10 nm) loaded on 3D reduced graphene oxide (rGO) (composite denoted as rGF) was successfully prepared. Characterization analyses have demonstrated that C–O–Fe bonds exist in rGF and CV test confirmed the cross-linked structure implemented by C–O–Fe is thermodynamically beneficial for electrons transport to Fe which is responsible for the regeneration of Fe(II). When the weight ratios of GO to Fe3O4 reach 5%, rGF-5, the optimized composite displays superior Fenton-like performance that the removal efficiencies of tetracycline hydrochloride (TCH) are 98.7% within 60 min and 96.1% within 90 min, with the initial pH 4.5 and pH 6.7, respectively. The excellent cyclic stability of rGF-5 further verifies the structure of electron-rich reaction microcenters on C–O–Fe bond bridges is well established to ensure that Fenton-like reactions continue to occur efficiently. The results of mass spectrometry indicate that products with m/z = 114 converted from TCH (m/z = 445) accounted for 87% at 60 min. This work not only achieves a way to construct high-performance heterogeneous Fenton-like catalysts for degradation of antibiotics, but also provides a new insight for designing various efficient catalysts based on the theoretical guidance.