BiVO4 modifying with cobalt-phosphate cluster cocatalyst for persulfate assisted photoelectrocatalytic degradation of tetracycline

Abstract

Tetracycline antibiotics pose a significant threat to environmental sustainability and human health due to their high concentration in water and soil beyond safety limits. In this study, we developed a BiVO4 photoelectrode modified with cobalt-phosphate cocatalyst hybrid nanocomposites to degrade tetracycline efficiently. The crystal structures of the composites and the chemical valence of the ions were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The photocurrent generated from BiVO4/Co-Pi under visible light irradiation (λ ≥ 420 nm) was 1.99 mA/cm2, which was 10.5 times higher than that from pristine BiVO4 film. The carriers’ dynamics were investigated by surface photovoltage spectroscopy (SPV) and transient photovoltage spectroscopy (TPV). BiVO4/Co-Pi demonstrated a 62.6% degradation rate of tetracycline within 60 min, which increased to 95.3% after adding peroxomonosulfate (PMS). Co-Pi cocatalyst facilitated charge separation and acted as the hole acceptor, thereby improving the degradation activity. Based on electron spin resonance (ESR) analysis, holes were identified as the dominant oxidizing species in the system. The activated Cobalt-phosphate cocatalyst along with the photogenerated-electrons facilitated the cobalt cycle process and generated sulfate radicals (•SO4−) via PMS activation, leading to efficient tetracycline degradation.