The planetary boundary corresponding to chemical pollution has been exceeded, with humans and the environment experiencing negative consequences from exposure to novel chemical entities.1 Synthetic organic pollutants contribute to the exceeding of this planetary boundary, and these can be captured from the environment. However, conventional remediation strategies fall short on processing contaminants into safe and benign products. Thus, large chemical stockpiles exist in Australia until an adequate destruction approach becomes available to destroy these contaminants. Photocatalysis is an enticing method that can be used to remediate synthetic organic pollutants and re-establish Earth in its safe operating space. A photocatalyst that can effectively break down all types of organic pollutants into non-harmful products is yet to be discovered,2,3 and herein, AgNbO3 with a perovskite structure is investigated. This material can absorb visible light, and the redox potential of the material’s valence and conduction bands enables the photocatalyst to drive chemical transformation through reduction and oxidation reactions.3 AgNbO3 was prepared by a solid-state synthesis and doped with lanthanum to reduce nanoparticle size and electron-hole recombination to enhance photocatalytic activity. Samples were characterised using powder X-ray diffraction, ultraviolet visible diffuse reflectance spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Silver nanoparticles were observed on the surface of the photocatalyst, and these increased in concentration with lanthanum doping. The dopant concentration of La 20 mol% demonstrated the highest degradation of textile dye, methyl orange, with activity comparable to commercial photocatalyst TiO2. Minimal particle size reduction was observed, however, variable wavelength X-ray Photoelectron Spectroscopy conducted at the Australian Synchrotron revealed that with La doping, a change in the oxidation state of niobium is observed. In flow style reactions, the photocatalyst demonstrated activity after 10 cycles and scavenger experiments showed that the superoxide radical anion and photocatalyst holes were responsible for the degradation. The lanthanum-doped AgNbO3 was then tested on organic compounds containing recalcitrant chemical bonds, and degradation was observed. This positions this photocatalyst as a promising material for improving remediation strategies.
(1) Castree, N. Anthropocene and Planetary Boundaries. In The International Encyclopedia of Geography, John Wiley & Sons, Ltd., 2017; pp 1-14. DOI: https://doi.org/10.1002/9781118786352.wbieg0027.
(2) Day, M. L.; Hamza, A. M.; Evans, J. D.; Shearer, C. J. Excess Al Reduces Photocatalytic Activity of Al-Doped SrTiO3 ACS Appl. Nano Mater. 2026, 9, 4, 1748–1759. DOI: https://doi.org/10.1021/acsanm.5c04384
(3) Matthews, R. K.; Nguyen, H. T. L.; Yang, F.; Pukala, T. L.; Evans, J. D.; Shearer, C. J. La Doping ATaO3 (A = Li, Na, K) to Improve Performance for Photocatalytic Pollutant Degradation. Chemistry of Materials 37(10):3696-3708 DOI: https://doi.org/10.1021/acs.chemmater.4c03443