Single-atom iron cocatalyst for highly enhancing TiO2 photocatalytic degradation of antibiotics and antibiotic-resistant genes

The efficient and sustainable utilization of solar energy and biomass resources through photocatalysis is important for achieving a carbon–neutral energy cycle. Here, we report an efficient photocatalyst SA-Fe@TiO2, where single-atom Fe sites are anchored to nitrogen-doped biochar and coupled with anatase TiO2. This innovative biochar-supported single-atom catalyst serves as a novel cocatalyst that can facilitate charge carrier separation and transfer. SA-Fe@TiO2 achieves an increase of 4.3 times in apparent rate constant for the degradation of the antibiotic sulfamethoxazole (SMX) and exhibits superior capacity for inactivating antibiotic-resistant genes compared with pure TiO2. Experimental evidence reveals the remarkable resistance of SA-Fe@TiO2 against environmental interferences, unveiling the involvement of three primary reactive species (h+, •OH, and •O2−) in SMX photodegradation. In addition, we fabricate immobilized SA-Fe@TiO2 films that effectively degrade five distinct antibiotics within 20 min. This study presents a new method for developing single-atom photocatalysts for highly efficient environmental remediation in the context of carbon neutrality.