Selective CO<sub>2</sub> Reduction Electrocatalysis\nUsing AgCu Nanoalloys Prepared by a “Host–Guest”\nMethod

Multimetallic\nnanoalloy catalysts have attracted considerable interest\nfor enhancing the efficiency and selectivity of many electrochemically\ndriven chemical processes. However, the preparation of homogeneous\nbimetallic alloy nanoparticles remains a challenge. Here, we present\na room-temperature and scalable, host–guest approach for synthesis\nof dilute Cu in Ag alloy nanoparticles. In this approach, an ionic\nsilver bromide precursor harboring exogenous Cu cations is reduced\nto yield ∼20 nm diameter AgCu alloy nanoparticles wherein the\n% Cu loading can be tuned precisely. AgCu nanoparticles with a 5%\nnominal loading of Cu exhibit peak activity (−0.23 mA/cm<sup>2</sup> normalized partial current density) and selectivity (83.2%\nfaradaic efficiency) for CO product formation from electrocatalytic\nreduction of CO<sub>2</sub> at mild overpotentials. These AgCu nanoalloys\nexhibit a higher mass activity compared to Ag- and Cu-containing nanomaterials\nused for similar electrocatalytic transformations. Our host–guest\nsynthesis platform holds promise for production of other nanoalloys\nwith relevance in electrocatalysis and optics.