Fabrication of MoS2@BL-BiVO4 photoanode with promoted charge separation for photoelectrochemical sewage treatment to simultaneously degrade PPCPs, disinfect E. coli, and produce H2: Performance, mechanisms, and influence factors

Abstract

Pharmaceuticals and personal care products (PPCPs) and Escherichia coli (E. coli) are ubiquitous in sewage posing adverse effects on both ecosystems and human health. Herein, we propose a multifunctional photoelectrochemical (PEC) system to simultaneously degrade PPCPs, disinfect E. coli, and produce H2. To this end, an optimized MoS2@BL-BiVO4 photoanode with reduced bulk and surface charge recombination was synthesized, exhibiting a photocurrent density of 2.21 mA/cm2 at 1.0 V vs. Ag/AgCl in actual sewage, 8.1 times that of P-BiVO4. The MoS2@BL-BiVO4 photoanode achieved complete degradation of 2 ppm benzophenone-3 and inactivation of E. coli in sewage with 89.32 μmol H2 evolution at 1.0 V vs. Ag/AgCl in 30 min. Chloride ions in the sewage played a critical role in the PEC system: they were activated to become chloride-based radicals (Cl, ClO) for sewage treatment and worked as hole scavengers to increase H2 evolution. Natural organic matters in the sewage played a dominant role in impeding the PEC reactions because they can quench the reactive species and were adsorbed onto the photoanode’s surface to block charge separation. The PEC system shows good efficiency when degrading various PPCPs, and excellent reusability and stability, giving it great practicality.