Unlocking the Selectivity of Pt–Ru Catalysts for Electrochemical Reduction of Acetone to Isopropanol

Electrochemically active liquid organic hydrogen carriers (EC-LOHCs) present a promising strategy for sustainable energy storage and conversion. Among them, the isopropanol/acetone redox pair is particularly attractive, but selective electrochemical hydrogenation of acetone remains a key challenge. Here, we identify the active state of bimetallic Pt-Ru catalysts that enables unprecedented selectivity for isopropanol formation. This state consists of ultrasmall metallic Pt aggregates supported on a roughened Ru surface formed exclusively through electrochemical dealloying of Pt-Ru alloys. Structures with similar activity cannot be attained by vacuum-based deposition methods. Using cyclic voltammetry, synchrotron radiation photoelectron spectroscopy, electrochemical infrared reflection absorption spectroscopy, and differential electrochemical mass spectrometry, we establish a direct link between surface structure and product selectivity. The same active state also promotes isopropanol oxidation at low overpotential, enabling bidirectional catalysis. These findings uncover a previously unrecognized pathway to tune catalyst selectivity and lay the groundwork for reversible EC-LOHC systems that support efficient, closed-loop, and carbon-neutral energy technologies.