Accelerated activation of H2O2 and persulfate by Sm-doped ZnO@highly-defective layered yttria nanocomposite under visible-light irradiation for dyeing wastewater treatment: Comprehensive dominance of oxygen vacancies in photocatalytic advanced oxidation processes

Herein, innovative visible-light-driven nano-photocatalysts for accelerated-activation of H2O2 and persulfate (PS) are explored towards degradation of ionic-dyes from wastewater. Highly-defective yttria-layers (D-Y2O3) are customized and used for stabilization of ZnO and Sm-doped ZnO (Sm-ZnO) nanoparticles. Comparing to ZnO@D-Y2O3, Sm-ZnO@D-Y2O3 nanocomposite possesses advanced surface-area and porosity with significant surface-heterogeneity, elevated negatively-charged nanoparticles (zeta(av) = -36.3 mV), large populations of oxygen vacancies, and enhanced visible-light absorptivity. PS-activation over visible-light-driven Sm-ZnO@D-Y2O3 photocatalyst (Sm-ZnO@D-Y2O3/PS/Vis) displays superior degradation efficiency (similar to 100 %) of isosulfan-blue, Bismarck-brown, and methylene-blue dyes within 10 min, near-complete mineralization performance, and great cyclability. Such excellent photodegradability results from (i) synergistic combination of nanocomposite-PS-visible light, yielding highly-developed synergy-index values (SI = 3-20), (ii) abundant generation of reactive-oxidizing-species (SO4 center dot-/h(+)/(OH)-O-center dot synergistic ratio 1:1.8:1.9), and (iii) facilitated transference of photoexcited-electrons across oxygen vacancies in yttria-moiety, prohibiting electron-hole pairs recombination. Hence, Sm-ZnO@D-Y2O3/PS/Vis system is an extraordinarily candidate for complete destruction of organic-pollutants via newly photocatalytic-mechanism, whatever it treats it degrades. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, innovative visible-light-driven nano-photocatalysts were explored for the accelerated activation of H2O2 and persulfate (PS) towards the degradation of ionic dyes in wastewater. Highly-defective yttria-layers (D-Y2O3) were customized and used for the stabilization of ZnO and Sm-doped ZnO (Sm-ZnO) nanoparticles. The Sm-ZnO@D-Y2O3 nanocomposite exhibited advanced surface area and porosity, significant surface heterogeneity, elevated negatively charged nanoparticles, large populations of oxygen vacancies, and enhanced visible-light absorptivity. The Sm-ZnO@D-Y2O3/PS/Vis system displayed superior degradation efficiency, near-complete mineralization performance, and great cyclability, making it an excellent candidate for the complete destruction of organic pollutants via a newly discovered photocatalytic mechanism.