Amination strategy improves efficiency of carbon dioxide electrocatalytic reduction

Carbon dioxide (CO₂) electrocatalytic reduction driven by renewable electricity can solve the problem of excessive CO₂ emissions. Since CO₂ is thermodynamically stable, efficient catalysts are needed to reduce the energy consumption in the process.

The single-atom catalysts immobilized on nitrogen-doped carbon supports (M-N/C) have been widely used for CO₂ electrocatalytic reduction reaction due to their high atom utilization efficiency.

Recently, a research team led by Prof. Liu Licheng from the Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) of the Chinese Academy of Sciences (CAS) proposed a two-step amination strategy to regulate the electronic structure of M-N/C catalysts (M=Ni, Fe, Zn) and enhance the intrinsic activity of CO₂ electrocatalytic reduction.

In the strategy, the M-N₄/C was aminated by annealing with carbamide in NH₃, impregnation and hydrothermal reaction in ammonia water to synthesize final M-N₄/C-NH₂ catalysts.

Although M-N/C catalysts are widely used, they demonstrate a poor reaction current density, which is much worse than the current density of industrial level.

In the study, the researchers used gas diffusion electrodes to create a reactive three-phase interface in a flow electrolyzer to increase the current density for CO production to industrial application level.

The aminated Ni single-atom catalyst demonstrated a remarkable current density of >400 mA cm^-2 with a nearly 90% Faraday efficiency for CO production, which is 1.8 times of that before amination.