Toward Highly Selective Electrochemical CO2 Reduction using Metal-Free Heteroatom-Doped Carbon.

ABSTRACT

There are growing interests in metal-free heteroatom-doped carbons for electrochemical CO2 reduction. Previous studies extensively focus on the effect of N-doping, and their products severely suffer from low current density (mostly <2 mA cm-2) and limited selectivity (<90%). Here, it is reported that heteroatom codoping offers a promising solution to the above challenge. As a proof of concept, N,P-codoped mesoporous carbon is prepared by annealing phytic-acid-functionalized ZIF-8 in NH3. In CO2-saturated 0.5 m NaHCO3, the catalyst enables CO2 reduction to CO with great selectivity close to 100% and large CO partial current density (≈8 mA cm-2), which are, to the best of knowledge, superior to all other relevant competitors. Theoretical simulations show that the improved activity and selectivity are stemmed from the enhanced surface adsorption of *COOH and *CO intermediates as a result of the synergy of N and P codoping.