Pd−Bi Bimetallic Nanochains for Electroreduction of CO2 to Syngas in Ionic Liquid‐Based Electrolytes

Abstract

AbstractThe electroreduction of carbon dioxide (CO2) is a sustainable method for generating valuable chemicals; however, avoiding unwanted hydrogen (H2) production during the electrolysis is a major challenge. Coproduction of carbon monoxide (CO) and H2 to produce syngas is an effective strategy for solving this problem, and syngas with a desired CO/H2 ratio can be employed to produce methanol or other valuable chemicals. Herein, a series of palladium‐bismuth (Pd−Bi) bimetallic nanochains with different Pd/Bi atomic ratios were prepared and used in the electroreduction of CO2 to syngas in ionic liquid‐based electrolytes. The ratio of CO/H2 in syngas was regulated in a wide range from 1 : 7 to 9 : 1 by controlling the applied potentials, Pd/Bi atomic ratios and composition of the electrolytes. In particular, the current density reached 19.3 mA cm−2 on Pd3Bi bimetallic nanochains at an applied potential of −2.3 V versus Ag/Ag+ when the CO/H2 ratio was approximately 1 : 1. Moreover, the maximum CO Faradaic efficiency was 87.7 % for these electrocatalysts at an applied potential of −2.0 V versus Ag/Ag+. The synergistic effect of Pd and Bi in the ionic liquid‐based electrolyte was the primary reason for the distinct electrocatalytic efficiency of the Pd3Bi bimetallic nanochains. The incorporation of moderate amounts of Bi into the Pd lattice resulted in a stronger CO2 adsorption capacity, more active sites and faster electron transfer rate, which are conducive to improving the electrocatalytic activity.