Industrial‐Level CO₂Electroreduction Using Solid‐Electrolyte Devices Enabled by High‐Loading Nickel Atomic Site Catalysts

Abstract

to reduce greenhouse gas and store renewable electricity in the form of chemical bonds. [1,2] During CO 2 RR process, a variety of products (such as carbon monoxide, formic acid, methane, methanol, ethylene, ethanol, n-propanol, etc) can be obtained through different reaction pathways depending on the electrode catalysts used. [3,4] Among these products, CO is a significant C1-building block required for various practical industrial routes, such as methanol synthesis, Fischer-Tropsch reactor and hydroformylation reaction. [4][5][6] More importantly, CO 2 RR to CO is regarded as one of the most promising routes for the chemical industry, owing to its high selectivity and spontaneous separation from electrolyte. Currently, different catalysts, such as metals and their alloys, molecular catalysts, carbon materials and metal atomic site materials, have been developed to promote the conversion of CO 2 to CO. [7][8][9][10][11][12][13][14][15] Among them, the atomic site catalysts (ASCs), especially N-doped carbon supported Ni-based ASCs (Ni-ASCs), are of more interest because of their high selectivity toward CO 2 RR to CO, tunable electronic structure, and low cost. [16][17][18][19][20][21][22] Although great progress has been achieved in making Ni-ASCs, the reported Ni atomic site catalysts usually show the limited current density at the level of Transition-metal atomic site catalysts (ASCs) are a new class of catalytic system for CO 2 electroreduction, however, their practical application is greatly hindered by the challenge that it's still difficult for them to simultaneously achieve industrial-level current density and high selectivity. Herein a new strategy is reported for hundreds of gram-scale and low-cost production of Ni-ASCs on 3D porous nanocarbon with high-loading NiN 3 sites for greatly boosting the electroreduction of CO 2 to CO with both industrial-level current density and high selectivity. It is discovered that although Ni-ASCs with high-loading (Ni-ASCs/4.3 wt.%) and low-loading (Ni-ASCs/0.8 wt.%) both show above 95% Faradic efficiency for CO (FE CO ) under a wide potential range in H-cell, in flow cell, Ni-ASCs/0.8 wt.% can only achieve FE CO of 43.6% at a current density of 343.9 mA cm −2 , significantly lower than those (95.1%, 533.3 mA cm −2 ) of Ni-ASCs/4.3 wt.% under same potential, first revealing the important role of high-loadings of single atom sites in promoting the highselectivity electrolysis at industrial-level current density. Most importantly, it is demonstrated that Ni-ASCs/4.3 wt.%-based membrane electrode assembly (MEA) exhibits outstanding durability at industrial-level current density of 360.0 mA cm −2 , which is one of the best performances for the realistic electroreduction of CO 2 to CO in the reported ASCs-based MEA systems.

Emerging Metal Single-Atom Materials: From Fundamentals to Energy Applications

“…Recently, our group developed a new scalable multiple anchoring strategy for fabricating hundreds of gram-scale high-loading Ni-based MSAs of up to 4.3 wt % (Ni-ASCs/4.3 wt %) as efficient CO 2 RR catalysts (Figure 7e). 57 This new strategy can guarantee the generation of high-density Ni MSAs on 3D porous carbon matrice. The porous carbon-supported high-density Ni MSAs with a Ni−N 3 configuration have rapid mass transfer capability and abundant active sites.…”

“…(g) Photographs of membrane electrode assembly (MEA) CO 2 electrolyzer. Reproduced with permission from ref . Copyright 2022 Wiley-VCH.…”

“…In addition to increasing the mass loading of MSAs, mass-producing high-quality MSAs and achieving industrial-scale high-current CO 2 electrolysis while maintaining high activity and selectivity are of great significance for promoting the practical use of the CO 2 RR. Recently, our group developed a new scalable multiple anchoring strategy for fabricating hundreds of gram-scale high-loading Ni-based MSAs of up to 4.3 wt % (Ni-ASCs/4.3 wt %) as efficient CO 2 RR catalysts (Figure e) . This new strategy can guarantee the generation of high-density Ni MSAs on 3D porous carbon matrice.…”

Nitrogen-Adsorbed Hydrogen Species Promote CO2 Methanation on Cu Single-Atom Electrocatalyst

“…The total current density was retained at a stable level for over 60 000 s. The FE CH4 showed a decreasing trend from 62.1 to 36.5%, possibly due to the bicarbonate deposition and flooding phenomena. 12 After rinsing of the electrode, the FE CH4 was recovered to 42.1%, indicating the excellent electrochemical stability. After the electrolysis, the catalyst's morphology and composition were characterized by SEM (Figure S24) and XPS (Figure S25), both of which were similar to those before the electrolysis.…”

“…Nonetheless, for metal–nitrogen-doped carbon single-atom catalysts, it is still ambiguous to distinguish whether the main source for *COOH formation to form CH 4 is the *H adsorbed on nitrogen atoms or carbon atoms. Moreover, the current densities of reported single-atom catalysts are typically limited at the level of tens of milliampere, probably attributed to the insufficient catalytic sites for CO 2 electroreduction. Achieving industrial-grade current densities of above 200 mA cm –2 for CO 2 electroreduction with high catalytic selectivities still remains a great challenge.…”