Electrochemical CO<sub>2</sub> reduction reaction catalytic activity of zirconium nitrides synthesized by the urea-glass route using ZrCl<sub>4</sub> as a raw material

The development of the electrochemical CO2 reduction reaction (CO2RR) catalyst is attracting attention, assuming the use of surplus electricity from renewable energy sources. As a product of CO2RR, carbon monoxide is actively studied because CO can be converted to other useful chemical substances. In this study, we focused on ZrN nanoparticles as a novel catalyst for CO2RR. ZrN was prepared by a liquid-phase process, the so-called “urea-glass route”. In the X-ray diffraction pattern of products, the peaks of ZrN were only confirmed. The elemental analysis showed that the obtained samples contained residual carbon, suggesting the composite of ZrN and carbon. Scanning electron microscope observation showed that the size of ZrN nanoparticles was approximately 100 nm, and the nanoparticles were aggregated. The CO2RR tests showed that the Faradaic efficiency of carbon monoxide formation was 22 %, and that of hydrogen was 54 % at −0.8 V vs. RHE. Although the Faradaic efficiency for carbon monoxide was relatively small, we confirmed the electrochemical CO2RR activity of ZrN-carbon composite.