Molecular Evidence for Metallic Cobalt Boosting CO₂ Electroreduction on Pyridinic Nitrogen

Abstract

Nitrogen‐doped carbon materials (N‐Cmat) are emerging as low‐cost metal‐free electrocatalysts for the electrochemical CO2 reduction reaction (CO2RR), although the activities are still unsatisfactory and the genuine active site is still under debate. We demonstrate that the CO2RR to CO preferentially takes place on pyridinic N rather than pyrrolic N using phthalocyanine (Pc) and porphyrin with well‐defined N‐Cmat configurations as molecular model catalysts. Systematic experiments and theoretic calculations further reveal that the CO2RR performance on pyridinic N can be significantly boosted by electronic modulation from in‐situ‐generated metallic Co nanoparticles. By introducing Co nanoparticles, Co@Pc/C can achieve a Faradaic efficiency of 84 % and CO current density of 28 mA cm−2 at −0.9 V, which are 18 and 47 times higher than Pc/C without Co, respectively. These findings provide new insights into the CO2RR on N‐Cmat, which may guide the exploration of cost‐effective electrocatalysts for efficient CO2 reduction.

Advances in Metal Phthalocyanine based Carbon Composites for Electrocatalytic CO2 Reduction

“…Recently, researchers have used phthalocyanine (Pc) and porphyrin with a clear nitrogen-carbon configuration as the catalyst was analyzed by electrocatalysis experiment. [71][72] Through Raman spectrum characterization and TEM image analysis of the catalytic material, it was found that the structure of the metal phthalocyanine did not change before and after electrocatalytic carbon dioxide, and no CoÀ N bond was formed. It was observed by XPS that metal cobalt and phthalocyanine interacted and had good stability.…”

“…In this experiment, the catalytic active site for carbon dioxide reduction is Co(I), although the electronwithdrawing substituent (cyano) can reduce the nucleophilic 111, Pc and Co(111)@Pc at 0 V vs. RHE (the asterisk itself (*) denotes the adsorption site and * with species means surface-bound species). [71] Reproduced with permission from Ref. 71 ability of the Co(I) site, which may lead to a reduction in the binding capacity of carbon dioxide.…”

“…[71] Reproduced with permission from Ref. 71 ability of the Co(I) site, which may lead to a reduction in the binding capacity of carbon dioxide. [81] However, the cyano group promotes the positive movement of the Co(II)/Co(I) oxidation-reduction potential, so that more Co(I) sites can be generated in the reaction.…”

Plasma-regulated N-doped carbon nanotube arrays for efficient electrosynthesis of syngas with a wide CO/H2 ratio

“…With different N-doping forms, the corresponding electrochemical CO 2 RR performance may exhibit a huge difference [24,25]. For instance, recent studies showed that pyridinic N atoms were more likely to adsorb CO 2 and serve as the favorable sites for CO 2 RR [26][27][28]. Accordingly, the CO 2 RR performances can be manipulated by regulating the component of the carbon materials.…”

Defect Engineering on Carbon-Based Catalysts for Electrocatalytic CO2 Reduction

“…Excessive carbon dioxide (CO 2 ) generated by combustion is discharged into the atmosphere, which seriously disrupts the original normal carbon cycle of nature, causing global warming, and then causes a series of serious environmental problems [1,2], such as sea level rise, land desertification, and climate abnormality. Therefore, the capture and conversion of CO 2 into fuel or chemical raw materials with high added value has become one of the hot spots of scientific research because it can provide solutions to carbon emissions and energy crisis at the same time [3][4][5][6][7][8]. In the past few decades, various technologies such as biochemical, electronic, photochemical, radiochemical, and thermochemical have been developed to reduce CO 2 [9][10][11][12].…”