Enhanced Dissolution of Pt from Pt–Zn Intermetallic Compounds and Underpotential Dissolution from Zn-Rich Alloys

Abstract

Anodic dissolutions of Pt and Zn from Pt−Zn compounds in 5 mol L −1 hydrochloric acid have been directly monitored by the channel flow double electrode method to investigate the mechanism of enhanced dissolution of precious metals by alloying with less noble metals. The enhancement of Pt dissolution shows strong dependence on the compound composition formed during the alloying process and is more prominent from r-PtZn 1.7 and γ 1 -Pt 3 Zn 10 than υ-PtZn and γ-Pt 2 Zn 11 . In addition, linear sweep voltammograms of Pt−92% Zn alloys show dissolution of Pt below 0.2 V vs SHE, which is far lower than the standard potential for the reaction (0.74 V). The result is explained by an activation of Pt through the preferential dissolution of Zn from the alloys. Such theoretically proposed "underpotential dissolution" is demonstrated for Pt−Zn alloys experimentally for the first time in the present study.

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Platinum Recovery Techniques for a Circular Economy

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