Addressing challenges of BiVO4 light-harvesting ability through vanadium precursor engineering and sub-nanoclusters deposition for peroxymonosulfate-assisted photocatalytic pharmaceuticals removal
Marta Kowalkińska, Alexey Maximenko, Aleksandra Szkudlarek, Karol Sikora, Anna Zielińska‐Jurek
Abstract
• A novel approach to the synthesis of NH 4 VO 3 and BiVO 4 was developed. • Ofloxacin and naproxen degradation under visible light was studied. • XANES measurements indicated the presence of CuO x sub-nanoclusters. • LVRPA analysis confirms better light utilisation of new BiVO 4 photocatalysts. • Toxicity assessment using Vibrio fischeri bacteria was compared with QSAR modelling. In this study, we present a complex approach for increasing light utilisation and peroxymonosulfate (PMS) activation in BiVO 4 -based photocatalyst. This involves two key considerations: the design of the precursor for BiVO 4 synthesis and interface engineering through CuO x sub-nanoclusters deposition. The designed precursor of ammonium methavanadate (NH 4 VO 3 , NHV) leads to reduction in particle size, better dispersion and improved light harvesting ability, confirmed by the calculations of the local volume rate of photon absorption (LVRPA) using the Six-Flux Radiation Absorption-Scattering model. The morphological changes result in a significant improvement in photocatalytic activity under visible light for the degradation of pharmaceuticals (naproxen and ofloxacin) compared to the commercial NH 4 VO 3 . Additionally, CuO x sub-nanoclusters were deposited on designed BiVO 4 and characterised using X-ray absorption near edge structure (XANES). The presence of sub-nanoclusters enhanced charge carriers separation, resulting in an increase in the apparent rate constants of 1.60 and 3.32-times for photocatalytic NPX and OFL removal, respectively. The application of obtained Vis light active photocatalysts in the presence of 0.1 mM PMS resulted in remarkably more efficient degradation of NPX (100 % within 60 min) and OFL (98.2 % within 120 min). PMS/Vis420/CuO x /BiVO 4 system exhibited high stability and reusability in the subsequent cycles of photodegradation. However, high PMS dosage induced Bi leaching which may cause the instability of the photocatalyst. Finally, to address the environmental implications of pharmaceutical removal and adhere to the Guidelines for drinking-water quality, toxicity assessments using Vibrio fischeri bacteria were performed and compared to a quantitative structure–activity relationship (QSAR) model.