Ultralow-Loading, High Activity: Boosting Photocatalysis with Ag Single Atoms via Microenvironment and Interface Tailoring

This work departs from conventional single-atom loading strategies, instead focusing on the optimization of the single-atom Ag microenvironment and its interface states with the support to enhance catalyst performance. Therefore, through crystal plane and defect engineering, the (101) and (100) facets are exposed in oxygen-deficient anatase TiO2. Ag single atoms are anchored on the exposed facets at an ultralow loading of 0.043 wt %. Combined theoretical and experimental results reveal that annealing at 400 °C facilitates the optimal Ag single-atom adsorption configurations, whereby Ag atoms preferentially anchor at O sites and oxygen vacancies on the TiO2 (100) and (101) facets, forming Ag−O and Ag−Ti bonds, respectively. These configurations, driven by thermal annealing, result in optimized interfacial states that not only stabilize the single-atom Ag but also establish efficient atomic-level electron transfer pathways that enable the rapid extraction of photogenerated electrons, suppressing carrier recombination and enhancing charge separation. Despite ultralow Ag loading, the Ag/IO-TiO2-400 catalyst exhibits enhanced performance, achieving an approximately 2.2-fold increase in the rate constant compared to pristine inverse opal TiO2 (IO-TiO2). It degrades nearly 100% of RhB (50 mg L−1) within 20 min (rate constant: 0.2769 min−1) and 88.4% of BPA within 70 min.