Interlayer-release synthesis of Cu single atoms anchored on a heterogeneous photocatalyst for constructing Cu–Ov–Fe bimetallic active sites with ultrafast kinetics of activation of H2O2†
Abstract
The efficient and selective generation of highly active ˙OH in a heterogeneous Fenton-like process is closely related to the spatial arrangement of active sites, local electron density of reactive atoms, and configuration of H2O2 adsorption to the active centers. Herein, a facile interlayer-release approach for the synthesis of a Cu single atom coordinated defect-rich Fe2O3/CuFeO2 heterogeneous photo-Fenton-like catalyst (Cu–Ov–Fe2O3/CuFeO2) with abundant atomically exposed Cu–Ov–Fe sites is developed. The asymmetric Cu–Ov–Fe sites, coupled with their acidic microenvironment, significantly enhance the adsorption of the Lewis-base H2O2 in a side-on configuration. This, in turn, promotes the homolytic cleavage of O–O bonds and selectively generates ˙OH. Fe2O3/CuFeO2 and agglomerated Cu clusters serve as the photosensitizers for efficient generation of photoexcited electrons, which are driven by a built-in electric field to the defect-rich Fe2O3 shell. Upon being trapped by the oxygen vacancies of Fe2O3, the electrons then flow directionally and get concentrated at the bimetallic Cu–Ov–Fe active sites, enhancing their electron density. The formation of the highly condensed localized electron density greatly improves the H2O2 activation kinetics. Benefitting from the excellent synergic effects of photocatalysis, single-atom catalysis, and asymmetric bimetallic activation effects, the well-designed Cu–Ov–Fe2O3/CuFeO2 exhibits record-breaking outstanding activity with TOF as high as 1.168 h−1 (99% degradation of phenol in 15 min), a remarkable selectivity of 78% for ˙OH, excellent durability with only 8% loss of activity after four runs and 23% loss after eight runs, and wide pH adaptability ranging from pH 4.5 to 9.