Mn-doped geopolymers photocatalysts with sustained-release OH- for highly efficient degradation of malachite green and tetracycline

Hydroxyl radicals (center dot OH) are the primary reactive groups in photocatalytic reactions. However, the stability and long-term effectiveness of photocatalysis in degrading dye wastewater and antibiotic contaminants remains a major challenge. In this study, the sustained-release microspheres containing OH- were prepared by Mn-doped metakaolin-based geopolymers (Mn-MGPs), and a strategy combining defect engineering and OH- sustained- releasewas presented. A large number of oxygen vacancies (O), which can enhance the light absorption prop-erties, can generate superoxide radicals (O2 center dot-) on the catalyst surface and promote the formation of (center dot OH) to fabricate efficient heterojunction photocatalysts. The photocatalysts were systematically characterized for pho-tocatalytic activity and long-term effectiveness in the degradation of malachite green (MG) and tetracycline (TC). The mechanism of the enhanced photocatalytic performance of the catalysts was investigated by characterization and DFT theoretical calculations, and the pollutant degradation pathway was proposed. This study provides an innovative approach to the controlled design of valence heterostructures.

Automated summary

Hydroxyl radicals are the primary reactive groups in photocatalytic reactions, but the stability and long-term effectiveness in degrading dye and antibiotic contaminants remain a challenge. In this study, sustained-release microspheres containing hydroxyl radicals were prepared using Mn-doped metakaolin-based geopolymers. A combination of defect engineering and sustained-release strategy was utilized to fabricate efficient heterojunction photocatalysts. The photocatalysts were characterized for their activity and long-term effectiveness in degrading malachite green and tetracycline. The enhanced photocatalytic performance and pollutant degradation pathway were investigated through characterization and theoretical calculations. This study provides an innovative approach to controlled design of valence heterostructures.