Electrochemical Reduction of CO2 with Exsolved Metal–Oxide Interfaces in a Proton-Conducting Solid Oxide Electrolyzer

Abstract

A large amount of carbon dioxide emissions have caused a greenhouse effect and even disrupted the global ecological balance. Therefore, it is urgent and significant to achieve emission reduction of CO2. The use of electrochemistry to reduce carbon dioxide into valuable chemicals and fuels is a sustainable strategy. Here, we present the electrochemical reduction of CO2 into CO in a proton-conducting solid oxide electrolyzer at a low temperature. We exsolve the active metal–oxide interfaces NixCu1–x–NbTi0.4Mn0.1O4−δ (NTMO) in a composite cathode by a synergistic doping strategy to increase the length and tailor the composition of the active interfaces and, hence, to promote CO2 reduction. By adjustment of the ratio of the nickel–copper alloy at the metal–oxide interface, it is found that the best performance can appear with an applied voltage of 0.8 V under the composition of Ni0.5Cu0.5–NTMO. A remarkable current efficiency of 99.8% is achieved with CO production at 0.71 mL min–1 cm–2 at a temperature as low as 600 °C. This illustrates the application prospects of electrochemical reduction of CO2 in a solid oxide electrolyzer through interface engineering.