In a recent study published in Angewandte Chemie International Edition, the research group led by Prof. WANG Yaobing at Fujian Institute of Research on the Structure of Matter of Chinese Academy of Sciences reported an efficient metal-free fluorine-doped carbon (FC) electrocatalyst for selective CO₂ reduction.

This study represented an unprecedented 250,000 times enhancement of CO₂ reduction activity on FC catalyst compared to non-doped catalyst. The HER activity was only ~20% of the non-doped catalyst. The highlight of this new doping strategy was the fluorine doping tuning the electron structure of the carbon atoms far from several bonds.

Researchers achieved the fluorine doping by a facial pyrolysis of commercial BP2000 and polytetrafluoroethylene with only ~0.3% fluorine content, which was much lower than nitrogen and boron doping (~5%). The obtained fluorine doped carbon (FC) showed 1.5 times enlarged electrochemical active surface compared to the non-doped carbon.

They found that the strong electronegativity of fluorine affect long-rang carbon atoms, activating them to be CDRR active sites and suppress their HER activity by stabilizing the CDRR key intermediate COOH*, and inhibiting the desorption of HER key intermediate H*. Thus, the inherent CDRR activity of FC was dramatically enhanced compared to the 1.5 times increased quantity of active sites, leading to 250,000 times enhancement of CO₂ reduction activity on FC.

The electrochemical CO₂ splitting cell equipped with FC catalyst as cathode could achieved 68% energy efficiency. When further coupled with a commercial solar cell, the hybrid device can convert solar energy to fuels with the energy efficiency of 13.6%.

The results proposed a new metal-free fluorine doped carbon catalysts and a novel doping mechanism for CO₂ reduction, which could promote the development of cost-effective artificial photosynthesis.