Promoting CO₂ Electroreduction Kinetics on Atomically Dispersed Monovalent Zn^I Sites by Rationally Engineering Proton‐Feeding Centers

Abstract

Electrocatalytic reduction of CO 2 (CO 2 RR) to valueadded chemicals is of great significance for CO 2 utilization, however the CO 2 RR process involving multi-electron and proton transfer is greatly limited by poor selectivity and low yield. Herein, We have developed an atomically dispersed monovalent zinc catalyst anchored on nitrogenated carbon nanosheets (Zn/NC NSs). Benefiting from the unique coordination environment and atomic dispersion, the Zn/NC NSs exhibit as uperior CO 2 RR performance,f eaturing ah igh current density up to 50 mA cm À2 with an outstanding CO Faradaic efficiency of % 95 %. The center Zn I atom coordinated with three Natoms and one Natom that bridges over two adjacent graphitic edges (Zn-N 3+1 )isidentified as the catalytically active site.Experimental results reveal that the twisted Zn-N 3+1 structure accelerates CO 2 activation and protonation in the rate-determining step of *CO 2 to *COOH, while theoretical calculations elucidate that atomically dispersed Zn-N 3+1 moieties decrease the potential barriers for intermediate COOH* formation, promoting the proton-coupled CO 2 RR kinetics and boosting the overall catalytic performance.

Boosting Electrochemical Carbon Dioxide Reduction on Atomically Dispersed Nickel Catalyst

“…However, their high cost seriously limits further application of these noble metal catalysts in ECO 2 R. To address these challenges, exploring carbon-based metal–nitrogen (M–N) catalysts with atomically dispersed transition metal sites would be a compelling choice due to their low cost, tunable structure, considerable activity, good stability, etc. Moreover, their well-defined coordination environment facilitates the clarification of the active sites and catalytic mechanism, as well as deeper investigation of the local microenvironmental effects on the activity ( Li Y et al, 2021 ; Chen et al, 2021 ; Lu et al, 2021 ).…”

“…Transitional M–N-based single-atom catalysts (SACs) have emerged as one of the novel class of carbon-based catalysts to replace the noble metal catalysts ( Chen et al, 2021 ). This is because of their ability to largely facilitate the ECO 2 R process while inhibiting the competing hydrogen evolution reaction (HER) by the virtue of their unique electronic structure, tailorable structure, and maximum atom utilization ( Yang Q et al, 2019 ).…”

Functional Aqueous Zinc–Acetylene Batteries for Electricity Generation and Electrochemical Acetylene Reduction to Ethylene

“…The as-designed Zn-C 2 H 2 battery under a pure acetylene stream exhibits a very large open circuit potential of 1.14 V, a high power density of up to 2.2 mW cm À 2 , and an energy density of 213.8 Wh kg Zn À 1 , which are much higher than those for reported Zn-CO 2 batteries. [18,[22][23][24][25][26][27][28][29][30][31][32][33][34] Even under a crude ethylene stream containing 1 vol. % acetylene impurities, the Zn-C 2 H 2 battery still exhibited an acetylene conversion of 99.97 %, an ethylene specific selectivity of 95 %, and eventually produced a polymer-grade ethylene feed with only � 3 ppm acetylene over a long-term discharge process.…”

“…Significantly, a peak power density of 2.22 mW cm À 2 was obtained at a current density of 12.6 mA cm À 2 , which unprecedentedly exceeded those for state-of-the-art Zn-CO 2 batteries such as 1.05 mW cm À 2 for N atoms and coordinatively unsaturated Ni-N 3 moieties coanchored carbon nanofibers (Ni-N 3 -NCNFs), [30] 1.24 mW cm À 2 for a surface-lithium-doped tin catalyst (s-SnLi), [27] 1.36 mW cm À 2 for a diatomic NiFe catalyst supported by nitrogen-doped graphene (NiFe-DASC), [28] and 1.8 mW cm À 2 for atomically dispersed monovalent zinc anchored on nitrogenated carbon nanosheets (Zn/NC NSs). [29] Markedly, the Zn-C 2 H 2 battery generated a stable open circuit potential of 1.14 V (Figure 1c), which was much larger than those for currently reported Zn-CO 2 batteries, for example 0.6 V for s-SnLi, [27] 0.79 V for cedar biomassderived N-doped graphitized carbon (CB-NGC-2), [33] and 0.82 V for carbon nanotubes directly grown on copper mesh (CNTs@Cu). [31] According to the mass change of the Zn anode before and after the discharge process at 6.0 mA cm À 2 , the specific capacity of the Zn-C 2 H 2 battery was calculated to be � 786 mAh g Zn À 1 (Figure 1d), corresponding to an energy density of 213.8 Wh kg Zn .…”

“…In contrast, current Zn-CO 2 batteries can only operate at low current densities of < 10 mA cm À 2 . [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] Furthermore, no ethane was detected, indicating that the overhydrogenation reaction of ethylene was effectively suppressed. As the discharge current density increased, the production rate of ethylene significantly increased to 5.8 mL cm À 2 h À 1 at 14 mA cm À 2 (Figure 2b).…”