Nanostructured metal-N-C electrocatalysts for CO2 reduction and hydrogen evolution reactions

Abstract

Major efforts are devoted to find efficient and selective electrocatalysts for solar fuel generation, thus enabling accelerated development of such technologies. A series of electrocatalysts from the metal–nitrogen–carbon (M–N–C) family was synthesized by a sacrificial support method (SSM). The salts of Cu, Mo, Pr, and Ce were employed as metal-precursors while the N–C network was formed by the high temperature pyrolysis of aminoantipyrine (AAPyr) organic compound. The structural and chemical features of the obtained electrocatalysts were characterized by SEM, XRD, TEM, BET, and XPS methods. Electrochemical characterization was performed towards CO2 electroreduction (CO2ER) and Hydrogen Evolution Reactions (HER) in neutral media. The metal-free N-doped carbon had a notable activity towards CO2ER, with the predominant formation of carbon monoxide (CO). This was also confirmed by isotopic labeling experiments, to exclude the possible contribution of the electrocatalyst as a carbon source. Upon introducing the metals into the carbon structure, the electrocatalytic activity towards HER increased. Particularly impressive current densities were achieved for the Cu and Mo-containing electrodes, where the presence of metal–N bonds was identified. These structural motifs are likely to be the electrocatalytic centers in the structure for the HER, which will be further studied for other metal-containing nanocarbons in our laboratories.