Low‐Energy CO₂ Reduction on a Metal‐Free Carbon Material

Abstract

Electrochemical CO 2 reduction to value-added chemicals on carbon-based catalysts is a potential approach for low-cost value-added CO 2 recycling. However, high overpotential and limited understanding of the mechanism remain challenging. Herein, a nitrogen and phosphorus co-doped carbon (NPC) material, which is synthesized through a simple pyrolysis, promoted low-energy electrochemical CO 2 reduction. The NPC electrocatalyst combines the advantages of active sites cooptimized by N and P, faster electrokinetics with bicarbonate providing proton, and more accessible active sites exposed by soft-template precursors. The NPC electrocatalyst exhibited more than ten-and fourfold enhancement of the partial current density of CO production compared to N-doped and P-doped carbon materials, respectively, with high selectivity (86 % faradaic efficiency) at only À 0.45 V. Experimental data coupled with density function theory calculations revealed that N and P dopants cooperated to enhance CO 2 adsorption, first electron transfer to CO 2 and then *COOH intermediate stabilization, leading to active and selective CO 2 -to-CO conversion. This work extends the design and understanding of metal-free carbonbased electrocatalysts for electrochemical CO 2 reduction.[a] Dr.adsorbates. The entropies of the free molecules were taken from the NIST database. [34][35][36] The solvent effect for stabilizing COOH* and CO* was 0.25 and 0.10 eV, respectively. [33] Due to the use of PBE functional, a further À 0.21 eV correction for the non-adsorbed gasphase CO molecule has been derived to accurately describe reaction free energy for CO 2 reduction to CO.

Metal–Organic Framework‐Based Electrocatalysts for CO2 Reduction

“…Metal-free carbon materials have recently attracted intensive attention due to their low cost, high surface area, and tunable conductivity, [178,179] which are among the most promising alternatives to the expensive noble metals for CO 2 RR. [180] Up to now, various kinds of heteroatom-doped carbon nanostructures, such as N-doped carbon, chlorine-doped carbon, [181] fluorine-doped carbon, [182] Se-doped carbon, [183] N-, B-codoped porous carbon, [184][185][186] nitrogen and phosphorus codoped carbon, [187] and graphene [188] have been explored for CO 2 RR. [189] In addition, the capacity to suppress the competing H 2 evolution reaction makes the N-doped carbon materials much more appealing for selective CO 2 conversion.…”

Metal‐Organic Frameworks Derived Electrocatalysts for Oxygen and Carbon Dioxide Reduction Reaction

“…Metal‐free heteroatom‐doped carbon materials have attained rigorous attentions as electrocatalysts for CO 2 RR because of their tunable conductivity [73] . Until now, different types of heteroatom‐doped carbon nano‐structures like N‐doped, chlorine‐doped, [74] fluorine‐doped, [75] Se‐doped [76] N and S co‐doped, [77] N and B co‐doped, [78] graphene [79] and N and P co‐doped [80] have been utilized for CO 2 RR process [81] . MOFs are deliberated as marvelous attractive agents for preparation of materials of porous.…”

Metal@hollow carbon sphere nanoreactors for sustainable biomass and CO2valorization

“…Representative heteroatom dopants are nitrogen (N), sulfur (S) and boron (B), which display electronegativity different from that of carbon atoms and could break the electroneutrality of the pure carbon structure, inducing charge redistribution and creating reactive sites for activation and adsorption of CO 2 . 228 Moreover, heteroatom-doped modified carbon-based catalysts have a high H 2 precipitation potential, which inhibits H 2 O reduction, leading to high energy efficiency and fast kinetics (Table 6). Chen et al 229 synthesized metal-free doped carbon catalysts with a highly homogeneous cylindrical channel structure by self-assembly of resol (carbon precursor), dicyandiamide (nitrogen precursor) and F127 (soft template).…”