First synthesis of the LaZnO biochar perovskite used as a photocatalyst with the enhanced deactivation mechenism and regenerable performance.

This study innovatively modified LaZnO perovskite with waste spirulina biochar to construct a new photocatalyst system, LaZnO-Biochar (LaZnO-B). For the first time, the low-temperature environment in the Northern Hemisphere was simulated to explore its visible - light degradation of sulfathiazole-type antibiotics and the regeneration strategy. At a low temperature of 0℃, LaZnO-B demonstrated outstanding activity, achieving a sulfathiazole (STZ) conversion rate of 56.5% within 5 min and maintaining 52.1% after 105 min, breaking through the bottleneck of low efficiency of traditional photocatalysts at low temperatures. Density functional theory (DFT) calculations revealed its structural advantages, with more active sites and a unique core-shell structure ensuring photocatalytic performance at low temperatures and pointing out a direction for the design of novel photocatalysts. The deposition of by-products and pollutants led to the catalyst deactivation. However, simple water rinsing could restore its activity. Even after three rinses, the STZ removal rate was still nearly 50%. This regeneration strategy is simple and efficient, showing great potential for application.