Effects of pore structures on a phenolic resin-derived self-supported electrode for highly efficient electroreduction of CO2 to syngas

Abstract

In this work, a self-supported electrode based on porous carbon sheets was prepared by a high-temperature calcination of a phenolic resin using hexamethylenetetramine as a nitrogen source and curing agent and KCl salt templates as pore-forming agents, and it was tested for the electrocatalytic reduction of CO₂ to syngas. The effects of the KCl addition amount on the morphology, pore structure, and electrocatalytic activity of the self-supported electrodes for CO₂ reduction were also investigated. The results indicated that the amount of KCl has significant impacts on the morphology, pore structure, N-containing species and electrochemical properties of carbon materials. Specifically, the electrode with a 40% KCl content had a maximum surface area of 71.29 m² g⁻¹, a medium pore size of 22.47 nm, and a CO Faraday efficiency of 48% at −1.2 V vs. Ag/AgCl with a current density of 10 mA cm⁻². Specifically, the H₂/CO molar ratio could be adjusted from 1.09 to 3.38 by changing the applied potential. The superior electrocatalytic performance is attributed to the high strength, large specific surface area, and suitable pore structure of the material. The high strength ensures a stable and sustainable reaction, the large specific surface area fully exposes the reactive active sites, and the suitable pore structure promotes the effective adsorption of reactant CO₂. The porous carbon sheet self-supported electrode designed in this experiment overcomes the disadvantages of expensive and short-lived precious metal catalysts and the need for adhesives in powder catalysts, providing a new strategy for the electrocatalytic conversion of CO₂ into ideal products at low potentials.