Efficient activation of peroxymonosulfate by Z-scheme NiCo2O4/BiVO4 heterojunctions for rapid degradation of tetracycline under visible light irradiation

The development of visible-light-assisted photocatalysts for the rapid reduction of transition metals is an effective approach for researchers to overcome the limited activation efficiency of peroxymonosulfate (PMS). Herein, Z-scheme NiCo2O4/BiVO4 heterojunction composite catalysts were designed to effectively activate PMS for the degradation of tetracycline (TC) under visible light irradiation. The structure, morphology, composition, and optical properties of the composite catalysts were investigated comprehensively and carefully, and the degradation performance of TC in the PMS/vis system was examined. 2-NiCo2O4/BiVO4 exhibited the highest degradation performance, and the effective removal of TC could be achieved within 10 min. The effects of different conditions on degradation experiments were clarified in detail. The optical behavior of the composite catalysts was analyzed in detail by surface photovoltage (SPV), transient photovoltage (TPV), UV–vis diffuse reflectance spectroscopy, and photoluminescence (PL) measurements. The experimental results showed that the constructed Z-scheme heterojunction achieved effective separation of photogenerated carriers, which enabled the rapid reduction of Ni3+ and Co3+, thus accelerating the activation of PMS and obtaining a large number of free radicals for pollutant removal. This Z-scheme NiCo2O4/BiVO4 heterojunction composite photocatalyst system provides new insights for the further development of photocatalytic synergistic PMS-based AOPs.