Study on phosphorous-doped cobalt-nitrogen-carbon catalysts for electrocatalytic reduction of carbon dioxide

The burning of fossil fuels has led to a rapid increase in the concentration of carbon dioxide (CO_2) in the atmosphere, resulting in a serious energy and environmental crisis. Electrocatalytic reduction of CO_2 to value-added chemicals and fuels, driven by renewable electricity, is an effective method for addressing the current depletion of fossil fuels. In this paper, a phosphorus-modified highly dispersible cobalt-nitrogen-carbon (Co-N-C) catalyst was prepared using a "one-pot" method. The catalyst′s morphology, element distribution, defect degree, surface element valence and coordination structure were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The performance of the catalyst in the electrocatalytic reduction of CO_2 to CO in an H-type cell was investigated. The results showed that the prepared Co-N-C/P catalyst exhibited a 97.0% CO Faraday Efficiency (FE_CO) at an applied potential of -0.9 V vs. RHE, with a current density of 4.58 mA/cm^2, and demonstrated stability over a 26-hour test. Compared with the Co-N-C catalysts, the P-dopant facilitated a good dispersion of Co atoms on the carbon black substrate, resulting in an approximately 38.9% increase in FE_CO. These findings demonstrated that the P-dopant significantly enhanced the performance of Co-N-C catalysts effectively for the electrocatalytic reduction of CO_2 to CO.