Metal-Free Fluorine-Doped Carbon Electrocatalyst for CO2 Reduction Outcompeting Hydrogen Evolution

Abstract

The electrochemical CO₂ reduction (ECDRR), as a key reaction in artificial photosynthesis to implement renewable energy conversion/storage, has been inhibited by the low efficiency and high costs of the electrocatalysts. Herein, we synthesize a fluorine-doped carbon (FC) catalyst by pyrolyzing commercial BP 2000 with a fluorine source, enabling a highly selective CO₂ -to-CO conversion with a maximum Faradaic efficiency of 90 % at a low overpotential of 510 mV and a small Tafel slope of 81 mV dec^-1 , outcompeting current metal-free catalysts. Moreover, the higher partial current density of CO and lower partial current density of H₂ on FC relative to pristine carbon suggest an enhanced inherent activity towards ECDRR as well as a suppressed hydrogen evolution by fluorine doping. Fluorine doping activates the neighbor carbon atoms and facilitates the stabilization of the key intermediate COOH* on the fluorine-doped carbon material, which are also blocked for competing hydrogen evolution, resulting in superior CO₂ -to-CO conversion.

Keywords: CO2 reduction; density functional calculations; energy conversion; fluorine; nanocatalysis.