Electrochemical reduction of CO2 to syngas using carbon gels-green graphene composites as metal free electrocatalyst

Abstract

The generation of syngas through the electro-reduction of CO2 and the subsequent H2 generation in a unified electro-conversion system emerges as a compelling strategy for the production of fuel precursors and chemicals. However, effective control of the CO:H2 ratio is imperative to ensure the system's practical application. This necessitates the utilization of electrocatalysts that exhibit active sites favoring both CO2 activation and regulated H2 generation, along with characteristics such as high conductivity, an extensive active surface area, and economical and sustainable synthesis methodologies. In this study, carbon xerogel microspheres doped with eco-graphene, which was obtained by environmentally friendly methods, have been synthesized. It has been observed that the inclusion of eco-graphene provides a high graphitic character, as well as nitrogenous groups and quinones. These features not only improve the selectivity for CO production, but also decrease the overpotential in both CO2 and water reduction reactions. The spherical morphology and porosity of the carbon xerogels have been shown to facilitate the accessibility of the reagents to the active sites, thereby enhancing the overall efficiency of the electrocatalysts. The optimal H2/CO ratio achieved in this study, ranging from 1 to 3, underscores the efficacy of the electrocatalysts in facilitating a single-vessel coupled Fischer-Tropsch synthesis. These electrocatalysts exhibit high selectivity for CO2 electro-reduction, attaining a maximum efficiency of 89.2 %.