Phosphorus and nitrogen doped CoNi nanocrystals supported on carbon based materials for electro- reduction of CO2 to syngas with controllable CO/H2

Abstract

The products of electrocatalytic CO2 reduction reaction (CO2RR) and hydrogen evolution reaction (HER) are the raw materials CO and H2 of synthesis gas respectively. The synthesis gas can generate usable fuel by Fischer Tropsch method to realize the carbon cycle. At present, it is still challenging to control the synthesis gas generation in the low potential and wide potential range. In order to solve this problem, we used a simple template method to embed different proportions of Ni and Co elements in the three-dimensional network structure of carbon carrier, between − 0.55 to − 1.15 V vs RHE, to generate synthetic gas with an adjustable CO/H2 ratio of 0.3–3. When Ni/Co ratio is 2:1(CoNi2 @NCP), the ratio of CO/H2 is kept at 1–3. At the potential of − 1.05 V vs RHE, the Faraday efficiency of CoNi2 @NCP catalyst to produce CO reaches 57 %, and that of H2 reaches 25 %. When the ratio of Ni-Co is 1:1 and 2:1, it can be used to produce methanol, ethanol and other alcohol products. Catalysts with different proportions can generate different synthesis gases at different potentials, which can be better used to generate downstream thermochemical synthesis of methane, ethylene, and alcohols. The sources of CO2RR and HER can be determined as Ni−Nx and Co−Nx sites by electrochemical analysis.