Afterglow-Catalysis and Self-Reporting of Pollutant Degradation by Ethylenediaminetetraacetic Acid Disodium-Etched Cr:ZnGa₂O₄

Both afterglow-catalysis and photoluminescence (PL) self-reporting of pollutant degradation are achieved by persistent luminescent ethylenediaminetetraacetic acid disodium (EDTA)-etched Cr³⁺-doped ZnGa₂O₄ (ZGO-EDTA). Afterglow-catalysis resolves the overdependence of traditional photocatalysis on continuous lighting, enabling pollutant degradation to proceed anywhere and at any time, in particular in dark environments. The self-reporting property allows the accurate determination of real-time degradation efficiency without the need for time-consuming tests. The effects of Cr³⁺-doping and EDTA-etching on those functions and properties were systematically investigated. Both Cr³⁺-doping and EDTA-etching improve the visible-light activatable afterglow, while EDTA-etching decreases the particle size, improves aqueous dispersibility, enlarges the surface area, and generates oxygen vacancies to slow down the recombination of photocarriers and prolong the duration of the afterglow, all of which contribute to the improved afterglow-catalysis and PL self-reporting of pollutant degradation. The related mechanism is discussed by combining experimental results with density functional theory calculations. Both PL self-reporting and afterglow-degradation have the potential to be widely deployed in the processing analysis of catalysis, environmental analysis and protection, and waste treatment, in a wider range of situations than was traditionally possible.