Tandem Catalyst to Enhance CO₂ Electroreduction to Methane

Carbon dioxide reduction reaction (CO₂RR) uses renewable electricity to convert carbon dioxide and water into fuels and chemicals, which is considered as an effective way to simultaneously realize carbon recycling and renewable energy storage.

The electrocatalytic conversion of carbon dioxide into hydrocarbons involves a multi-electron reduction reaction process, facing problems such as complex conversion pathways and difficulty in selectivity control.

A research group led by Prof. WANG Guoxiong and Prof. BAO Xinhe from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences enhanced CO₂ electroreduction to methane with cobalt phthalocyanine (CoPc) and zinc-nitrogen-carbon (Zn-N-C) tandem catalyst.

They achieved high activity of CH₄ production in CO₂RR on a non-copper-based catalyst, and provided a new strategy for the electrocatalytic reduction of carbon dioxide to hydrocarbons.

This work was published in Angew. Chem. Int. Ed. on Sept. 4.

CO₂ is firstly electrochemically reduced into CO and then CO diffuses to Zn-N-C for further conversion into CH₄ over CoPc@Zn-N-C tandem catalyst (Image by LIN Long and LIU Tianfu)

Compared with CoPc or Zn-N-C alone, the methane/carbon monoxide rate ratio of this CoPc and Zn-N-C tandem catalyst was increased by more than 100 times.

Density functional theory calculations and comparative experimental results showed that carbon dioxide was first reduced to carbon monoxide on the CoPc, and then the carbon monoxide diffused onto the Zn-N-C and was further converted into methane.

This tandem catalytic strategy converted carbon dioxide into methane and decomposed the process into tandem electrocatalytic reactions at two active sites. In this tandem catalytic system, CoPc provided carbon monoxide to retain the adsorbed hydrogen on the adjacent-nitrogen in the Zn-N site, thereby increasing the rate of methane production.

This work was supported by the National Natural Science Foundation of China, the National Key Research and Development Program, and the Youth Innovation Promotion Association of the Chinese Academy of Sciences. (Text by LIN Long and LIU Tianfu)