Porous Iron Oxide Core–Gold Satellite Nanocomposite: A Cost-Effective and Recyclable Solution for Photocatalytic Wastewater Treatment

Organic pollutants in wastewater pose serious threats to human health and the environment. Nevertheless, potent strategies are being devised to tackle this critical issue. Specifically, advanced oxidation processes driven by solar energy and photocatalysts show promise for the degradation of organic pollutants. In particular, porous nanomaterials are effective as photocatalysts because of their high surface area, light-harvesting properties, and ability to generate reactive oxygen species. To further expedite the development of feasible and sustainable organic-pollutant-degrading schemes, this article reports a strategy rooted in selective core etching for fabricating a core-satellite-type porous Fe₃O₄–Au nanocomposite. The Fe₃O₄ core behaves as a semiconductor to generate electron–hole pairs, whereas the Au satellite units serve as hot-electron donors under visible-light irradiation. The nanocomposite exhibits exceptional photocatalytic activity, degrading methylene blue molecules by 97% in just 1 h under visible light, and maintains its photocatalytic performance even after five rounds of recycling. Moreover, the nanocomposite achieves 90% tetracycline decomposition within 2 h. In addition to exhibiting noteworthy photocatalytic activity, the nanocomposite is magnetically separable, facilitating its recovery and reuse and exhibiting remarkable stability and cost-effectiveness. These attributes underscore the practical viability of the core-satellite-type Fe₃O₄–Au nanocomposite in wastewater treatment.