Hard-biotemplated sunlight photocatalyst with multilevel-regulated microstructural building units for degradation of ephedrine

[Display omitted] •Hard-biotemplated TiO2 with multilevel-regulated microstructural building units.•Multilevel regulation induced by co-mediation of the K+ and HF.•Enhanced efficiency for degrading EPH under both simulated and natural sunlight. The psychoactive substance ephedrine (EPH) has been recognized as an emerging contaminant of concern, and the application of photocatalysis technology for its degradation remains in its infancy. Hard-biotemplated TiO2 is a promising type of photocatalyst with the potential to efficiently degrade EPH under solar irradiation. However, current research on hard-biotemplated TiO2 has primarily focused on preserving the macrostructure morphology of the templates while overlooking the influence on the performance of the photocatalysts of the building unit microstructure of the macrostructure assembly. Herein, a new corn stalk-templated TiO2 (CS-TiO2(HF0.5)) with multilevel-regulated microstructural building units was prepared through the co-mediation of the K+ contained in the biotemplates and HF. The multilevel-regulated microstructural units for building the macrostructure inherited from corn stalks were classified into three levels. CS-TiO2(HF0.5) exhibited the highest photocatalytic efficiency under simulated sunlight, which was 11.3 and 3.0 times higher than that of pure TiO2 and conventional biotemplated CS-TiO2, respectively. Subsequently, natural sunlight was used as the light source for photocatalytic degradation of EPH over CS-TiO2(HF0.5). The removal rate of EPH over CS-TiO2(HF0.5) was nearly 100 % after 120 min under natural sunlight. The toxicity of EPH exhibited a notable decrease following photocatalytic degradation. The enhanced efficiency was due to the separation and migration efficiency of photogenerated hole-electron pairs induced by the surface heterojunction, as well as the increased diffusion and migration efficiencies of EPH induced by the multi-dimensional microstructural building unit construction and the multilevel pores.