The continuous increase of CO_­2 concentration in the atmosphere would potentially bring catastrophic global climate changes, which is one of the most urgent issues of the society. CO₂ electrochemical reduction (CO₂RR) is promising in simultaneously controlling the CO₂ concentration and store renewable energy. However, selectively producing valuable chemicals and fuels with reasonable low overpotentials is quite difficult.

In this study, Pd and Pd-Au nanowires with a varied composition were synthesized. The nanowires have a twisty morphology with a lot of grain boundaries. For the first time, highly selective CO₂-to-CO electrocatalytic conversion with low overpotentials was achieved on Pd-based nanocatalysts. All the synthesized nanowires exhibited significantly improved CO selectivity as compared to commercial Pd nanoparticles (Figure 1). At -0.6 V, a maximum faradaic efficiency over 94% can be obtained on Pd_0.8Au nanowires. CO can also be detected with a faradaic efficiency of 8.5% at an overpotential of merely 90 mV. The Pd-Au nanowires have superior mass and specific activities, which are highly dependent on the composition. In situ infrared spectroscopic studies with an attenuated total reflection configuration (ATR-IR) was conducted to reveal the combined structure and composition impacts on the activity. It was found that *CO could be more easily generated at much lower overpotentials on nanowires as compared to that on particles. Additionally, the alloying between Pd and Au would generate more linearly-bonded *CO, which is more facile to desorb and results in an improved reaction rate.

Figure 1. Faradaic efficiency of CO measured on Pd/C, synthesized Pd and Pd_0.8Au nanowires.