Advanced Oxidation Processes for Precious Metal Recycling

Precious metals, including Au, Ag, Pt, Pd, and Rh, are indispensable to modern catalysis, electronics, and emerging energy technologies, yet their scarcity and geographical supply chain vulnerabilities pose significant supply risks. At the same time, the rapid growth of electronic waste and spent catalysts has created a paradoxical situation in which primary resources remain constrained but secondary resources increasingly contain precious metal concentrations that match or even exceed those of natural ores. This tension has made precious metal recycling both a strategic necessity and a scientific challenge. Despite substantial progress in hydrometallurgy, the field remains heavily dependent on harsh leaching systems such as aqua regia and cyanidation, which suffer from poor selectivity, corrosive conditions, toxic reagents, and secondary environmental burdens. The central challenge is unchanged: chemically inert precious metals must first be oxidized into soluble species before downstream separation and purification can occur. Our work has approached this longstanding problem from a different perspective. Rather than relying on increasingly harsh reagents, we have begun to view precious metal dissolution as a controllable oxidation process that can be re-engineered through advanced oxidation processes. This shift has opened a new conceptual framework in which reactive oxygen species are deliberately harnessed to oxidize precious metals under substantially milder conditions. Within this emerging area, advanced oxidation is not simply borrowed from environmental catalysis for the degradation of pollutants; it is being redefined as a distinct methodological paradigm for precious metal metallurgy. In this Account, we summarize how this idea has evolved across several complementary platforms. We first discuss photocatalytic and piezocatalytic systems, where light or mechanical stimulation drives the formation of reactive species and solvent-derived ligands for metal dissolution. We then examine homogeneous persulfate-based Fenton-like systems, which transfer oxidant activation into the bulk solution and reveal how radical and nonradical pathways cooperate in oxidative leaching. Next, we highlight our recent efforts in single-atom catalysis, where isolated metal sites provide a bridge between molecular-level oxidant activation and heterogeneous robustness, enabling rapid and selective precious metal recovery with improved catalyst recyclability. Finally, we discuss self-catalytic leaching, an especially streamlined limit in which the precious metal itself participates in generating the oxidizing species required for its own dissolution. Together, these studies suggest that the future of precious metal recycling will be defined not solely by stronger oxidants but also by the rational integration of oxidative power, ligand coordination, interfacial control, and process sustainability. By tracing this development from fundamental mechanisms to scalable recovery strategies, this Account aims to show how advanced oxidation can reshape precious metal hydrometallurgy and provide a foundation for greener, more selective, and more versatile recycling technologies.