Precious metals such as gold and platinum are valued materials for a variety of important applications, but their scarcity poses a risk of supply disruption. Recycling precious metals from waste provides a promising solution; however, conventional metallurgical methods bear high environmental costs and energy consumption. Here, we report a photocatalytic process that enables one to selectively retrieve seven precious metals—silver (Ag), gold (Au), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru) and iridium (Ir)—from waste circuit boards, ternary automotive catalysts and ores. The whole process does not involve strong acids or bases or toxic cyanide, but needs only light and photocatalysts such as titanium dioxide (TiO2). More than 99% of the targeted elements in the waste sources can be dissolved and the precious metals recovered after a simple reducing reaction that shows a high purity (≥98%). By demonstrating success at the kilogram scale and showing that the catalysts can be reused more than 100 times, we suggest that this approach might be industry compatible. This research opens up a new path in the development of sustainable technologies for recycling the Earth’s resources and contributing to a circular economy.
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Fan, Z. & Zhang, H. Crystal phase-controlled synthesis, properties and applications of noble metal nanomaterials. Chem. Soc. Rev. 45, 63–82 (2016).
Zhao, M. et al. Metal-organic frameworks as selectivity regulators for hydrogenation reactions. Nature 539, 76–80 (2016).
Hunt, S. T. et al. Self-assembly of noble metal monolayers on transition metal carbide nanoparticle catalysts. Science 352, 947–978 (2019).
Commodity Statistics and Information (USGS, 2017); https://minerals.usgs.gov/minerals/pubs/commodity/
Li, B. et al. Recovery of platinum group metals from spent catalysts: a review. Int. J. Miner. Process. 145, 108–113 (2015).
Annual Consumption and Storage of Metals in the World (NIMS, 2015); http://www.nims.go.jp/jpn/news/press/pdf/press215_2.pdf
Yavuz, C. T. et al. Gold recovery from e-waste by porous porphyrin–phenazine network polymers. Chem. Mater. 32, 5343–5349 (2020).
Liu, C. et al. Economic and environmental feasibility of hydrometallurgical process for recycling waste mobile phones. Waste Manag. 111, 41–50 (2020).
Dato, P. Economic analysis of e-waste market. Int. Environ. Agreem. 17, 815–837 (2017).
Doidge, E. D. et al. A simple primary amide for the selective recovery of gold from secondary resources. Angew. Chem. Int. Ed. 55, 12436–12439 (2016).
Sun, D. T., Gasilova, N., Yang, S., Oveisi, E. & Queen, W. L. Rapid, selective extraction of rrace amounts of gold from complex water mixtures with a metal-organic framework (MOF)/polymer composite. J. Am. Chem. Soc. 140, 16697–16703 (2018).
Liu, Z. et al. Selective isolation of gold facilitated by second-sphere coordination with alpha-cyclodextrin. Nat. Commun. 4, 1855 (2013).
Yue, C. et al. Environmentally benign, rapid, and selective extraction of gold from ores and waste electronic materials. Angew. Chem. Int. Ed. 56, 9331–9335 (2017).
McGivney, E. et al. Biogenic cyanide production promotes dissolution of gold nanoparticles in soil. Environ. Sci. Technol. 53, 1287–1295 (2019).
Birich, A., Stopic, S. & Friedrich, B. Kinetic investigation and dissolution behavior of cyanide alternative gold leaching reagents. Sci. Rep. 9, 7191 (2019).
Ahtiainen, R. & Lundström, M. Cyanide-free gold leaching in exceptionally mild chloride solutions. J. Clean. Prod. 234, 9–17 (2019).
James Hutton: father of modern geology, 1726–1797. Nature 119, 582 (1927).
Lee, H., Molstad, E. & Mishra, B. Recovery of gold and silver from secondary sources of electronic waste processing by thiourea leaching. JOM 70, 1616–1621 (2018).
Burdinski, D. & Blees, M. H. Thiosulfate- and thiosulfonate-based etchants for the patterning of gold using microcontact printing. Chem. Mater. 19, 3933–3944 (2007).
Cho, E. C., Xie, J., Wurm, P. A. & Xia, Y. Understanding the role of surface charges in cellular adsorption versus internalization by selectively removing gold nanoparticles on the cell surface with a I2/KI etchant. Nano Lett. 9, 1080–1084 (2009).
Parga, J. R., Valenzuela, J. L. & Francisco, C. T. Pressure cyanide leaching for precious metals recovery. JOM 59, 43–47 (2007).
Lopes, P. P. et al. Dynamics of electrochemical Pt dissolution at atomic and molecular levels. J. Electroanal. Chem. 819, 123–129 (2018).
Lin, W. et al. ‘Organic aqua regia’—powerful liquids for dissolving noble metals. Angew. Chem. Int. Ed. 49, 7929–7932 (2010).
Hong, Y. et al. Precious metal recovery from electronic waste by a porous porphyrin polymer. Proc. Natl Acad. Sci. USA 117, 16174–16180 (2020).
Okesola, B. O., Suravaram, S. K., Parkin, A. & Smith, D. K. Selective extraction and in situ reduction of precious metal salts from model waste to generate hybrid gels with embedded electrocatalytic nanoparticles. Angew. Chem. Int. Ed. 55, 183–187 (2016).
Wang, H. et al. Semiconductor heterojunction photocatalysts: design, construction, and photocatalytic performances. Chem. Soc. Rev. 43, 5234–5244 (2014).
Cherevko, S. et al. Dissolution of noble metals during oxygen evolution in acidic media. ChemCatChem 6, 2219–2223 (2014).
Tian, J. et al. Kinetics on leaching rare earth from the weathered crust elution-deposited rare earth ores with ammonium sulfate solution. Hydrometallurgy 101, 166–170 (2010).
Zhou, J. et al. Leaching kinetics of potassium and aluminum from phosphorus-potassium associated ore in HCl-CaF2 system. Sep. Purif. Technol. 253, 117528 (2020).
Dong, C. et al. Size-dependent activity and selectivity of carbon dioxide photocatalytic reduction over platinum nanoparticles. Nat. Commun. 9, 1252 (2018).
Sun, C. & Xue, D. In situ IR spectral observation of NH4H2PO4 crystallization: structural identification of nucleation and crystal growth. J. Phys. Chem. C 117, 19146–19153 (2013).
Ennis, C., Auchettl, R., Ruzi, M. & Robertson, E. G. Infrared characterisation of acetonitrile and propionitrile aerosols under Titan’s atmospheric conditions. Phys. Chem. Chem. Phys. 19, 2915–2925 (2017).
Yu, H. L. et al. Unidirectional suppression of hydrogen oxidation on oxidized platinum clusters. Nat. Commun. 4, 2500 (2013).
Chaudhuri, P. et al. Electronic structure of bis(o-iminobenzosemiquinonato) metal complexes (Cu, Ni, Pd). The art of establishing physical oxidation states in transition-metal complexes containing radical ligands. J. Am. Chem. Soc. 123, 2213–2223 (2001).
Siemer, N. et al. Atomic scale explanation of O2 activation at the Au-TiO2 interface. J. Am. Chem. Soc. 140, 18082–18092 (2018).
Li, R. et al. Radical-involved photosynthesis of AuCN oligomers from Au nanoparticles and acetonitrile. J. Am. Chem. Soc. 134, 18286–18294 (2012).
Zheng, Z. et al. Facile in situ synthesis of visible-light plasmonic photocatalysts M@TiO2 (M = Au, Pt, Ag) and evaluation of their photocatalytic oxidation of benzene to phenol. J. Mater. Chem. 21, 9079–9087 (2011).
Bilski, J. et al. Photochemical reactions involved in the phototoxicity of the anticonvulsant and antidepressant drug lamotrigine (Lamictal@). Photochem. Photobiol. 85, 1327–1335 (2009).
Han, G. et al. Visible-light-driven valorization of biomass intermediates integrated with H2 production catalyzed by ultrathin Ni/CdS uanosheets. J. Am. Chem. Soc. 139, 15584–15587 (2017).
Hokuto, F. et al. Determining the composite structure of Au-Fe-based submicrometre spherical particles fabricated by pulsed-laser melting in liquid. Nanomaterials 9, 198 (2019).
Xiao, J. et al. Integration of plasmonic effects and schottky junctions into metal organic framework composites: steering charge flow for enhanced visible-light photocatalysis. Angew. Chem. Int. Ed. 57, 1103–1107 (2017).
Frens, G. Controlled nucleation for the regulation of the particle size in monodisperse gold suspensions. Nat. Phys. Sci. 241, 20–22 (1973).
Lee, P. C. & Melsel, D. J. J. Adsorption and surface-enhanced raman of dyes on silver and gold sols. J. Phys. Chem. 86, 3391–3395 (1982).
Liu, L., Gao, F. & Zhao, H. Tailoring Cu valence and oxygen vacancy in Cu/TiO2 catalysts for enhanced CO2 photoreduction efficiency. Appl. Catal. B 134–135, 349–358 (2013).
This work was supported by the National Key Research and Development Program of China (no. 2020YFA0211004), the National Natural Science Foundation of China (nos. 21876114 and 21761142011), Shanghai Government (nos. 19DZ1205102, 19160712900 and 18JC1412900), the Chinese Education Ministry Key Laboratory and International Joint Laboratory on Resource Chemistry, the Shanghai Eastern Scholar Program and the Shanghai Engineering Research Center of Green Energy Chemical Engineering (no. 18DZ2254200).
The authors have filed a patent application (US Patent application no. 17042775) on technology related to the processes described in this Article.
Peer review information Nature Sustainability thanks Sheng Dai, Bernd Friedrich and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Chen, Y., Xu, M., Wen, J. et al. Selective recovery of precious metals through photocatalysis. Nat Sustain (2021). https://doi.org/10.1038/s41893-021-00697-4