Acidic electrocatalytic reduction of CO2 has numerous advantages for widespread industry implementation, especially in efficient electrolyzer design. Although CO2 reduction has achieved nearly 100% Faradaic efficiency (FE) under neutral electrolytes, it still suffers from more serious hydrogen evolution reaction (HER) because of the higher proton concentration under acidic conditions. Herein, an acid-durable manganese-nitrogen-doped carbon catalyst was prepared by carbonization of precursor, which was formed by coordination of N-rich organic small molecule 3-cyanopyridine and manganese chloride. In 0.5 M KHCO3, CO was the only product detected within the broader potential range. Not only that, the maximum CO Faradaic efficiency (FECO) of 84.3% and the maximum partial current density (JCO) of 17.5 mA cm-2 have been reached by acid-leaching manganese-nitrogen-doped carbon (MnNC A) at pH of 2. The precursor exhibited improved thermal stability, and more N groups are retained and anchored in the multi-walled carbon nanotubes (the matrix ), which provides a large number of active sites for the adsorption of CO2. Compared with NiNC A electrochemical test in acidic conditions, HER is suppressed by CO2 reduction as MnNC A shows increased CO2 adsorption, and the reaction at the electrode surface could express as CO2 + H+ + 2 e- → CO + H2O. Manganese is introduced into the metal-nitrogen-carbon system to produce a highly efficient and low-cost Mn-based catalyst for acidic electrocatalytic reduction CO2, proving a direction of rational catalyst design used at low pH.

Manganese-nitrogen-doped carbon as an efficient catalyst for acidic electrocatalytic reduction of CO2

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