Edge-Engineered Interfacial Carrier Dynamics for Efficient Photocatalytic Gold Recovery

Developing highly efficient and sustainable precious metal recovery technologies is critical for meeting escalating global demand and mitigating the severe environmental impact of conventional metallurgy methods. Here, we report a novel edge-engineering strategy utilizing amino-functionalized graphitic carbon nitride (g-C₃N₄-NH₂) to achieve unprecedented performance in photocatalytic gold recovery. This material exhibits a state-of-the-art photocatalytic gold recovery capacity of 3819.3 mg g^-1, achieving an efficiency exceeding 99.7%, and ultrahigh selectivity (K_d = 2.97×10⁷ mL g^-1) in complex leachates. Comprehensive multiscale analyses reveal that the engineered -NH₂ sites, upon protonation to -NH₃ ⁺, govern preferential carrier dynamics. This mechanism enables a unique proton-coupled electron transfer (PCET) pathway that drives the highly efficient reduction of Au(III) and subsequent surface nanocrystal crystallization. To validate practical scalability, the g-C₃N₄-NH₂ catalyst was successfully integrated onto a polyurethane foam (PUF) matrix and rigorously tested in a custom, pilot-scale continuous-flow photoreactor. This system achieved a 99% gold recovery rate from diverse e-waste and ore leachates. A detailed techno-economic analysis confirms the commercial viability of this approach, projecting a 2431.2% return on investment, thereby establishing a scalable photometallurgy paradigm for solar-driven, highly selective, and sustainable precious metals recovery.