Maximizing the Pt–CuO _<i>x</i> interface by trace Cu boosts CO preferential oxidation

Preferential oxidation of CO (CO‐PROX) in H 2 ‐rich streams is highly important for purifying the industrial grade H 2 used in proton‐exchange‐membrane fuel cells (PEMFC), but it is still limited to a relatively narrow operation temperature window. In this study, the trace amounts of Cu are used to modify a Pt/Al 2 O 3 catalyst. The introduced Cu 2+ species are atomically anchored on Pt nanoparticles through strong electrostatic adsorption. The prepared Pt–Cu/Al 2 O 3 catalyst with 0.011 wt% Cu loading achieves complete CO oxidation between 138 and 215 °C, while the maximum CO conversion of Pt/Al 2 O 3 is only 94%. The characterization showed that the formation of the Pt–CuO x interface not only produced additional active sites for O 2 activation but also weakened the adsorption strength of CO due to Pt existing in an electron‐deficient state. The synergy at the interface of Pt–CuO x inhibits the competitive adsorption of CO and O 2 on Pt nanoparticles. Compared with CO oxidation, the presence of H 2 in CO‐PROX promotes CO oxidation through the formation of a formate (HCOO–) intermediate. The addition of Cu accelerates the HCOO– intermediate oxidation over Pt–Cu/Al 2 O 3 . The strategy of constructing metal‐oxide interfacial sites sheds light on designing better catalysts for the CO‐PROX reaction.