Synergy of Ni Nanoclusters and Single Atom Site: Size Effect on the Performance of Electrochemical CO₂ Reduction Reaction and Rechargeable Zn−CO₂ Batteries

Abstract

The design of bifunctional electrocatalysts toward reduction reaction of carbon dioxide (ECO2RR) and oxygen evolution reaction (OER) in aqueous rechargeable Zn─CO2 batteries (ZABs) still poses a significant challenge. Herein, Ni clusters (Nix) of 0.5 and 0.8 nm in diameter coupled with single Ni site (Ni−N4−C), denoted as Ni−N4/Ni5 and Ni−N4/Ni8, respectively, are synthesized and the size effect of Ni nanoclusters are studied. Ni−N4/Ni5 exhibits an ≈100% Faradaic efficiency (FECO) toward ECO2RR for CO from −0.4 to −0.8 V versus the reversible hydrogen electrode, superior to that of Ni−N4−C (FECO = 55.0%) and Ni−N4/Ni8 (FECO = 80.0%). The OER performance of Ni−N4/Ni5 and Ni−N4/Ni8 are superior or comparable to that of commercial RuO2 but outperform that of Ni−N4−C. Theoretical calculation indicates that *COOH of ECO2RR intermediates bond synergistically with Nix clusters and Ni−N4−C single atom site, promoting the activation of CO2 and reducing the energy barrier of the potential determining step of ECO2RR. Such effect is strongly size‐dependent and larger Nix nanoclusters result in too strong binding of *COOH intermediates, impede the formation of *CO. As a bifunctional cathode electrocatalyst of rechargeable alkaline aqueous ZABs, Ni−N4/Ni5 exhibits a peak power density of 11.7 mW cm−2 and cycling durability over 1200 cycles and 420 h.

Mechanistic insights into high-throughput screening of tandem catalysts for CO2 reduction to multi-carbon products

“…As reported in a previous work by Miao et al, DFT calculations were performed using 5-atom and 8-atom cluster models, demonstrating the feasibility of using metal clusters of such sizes for CO 2 ER. 24 And Chen et al employed 7 Cu atoms to represent the Cu cluster in the Cu-based tandem CO 2 ER electrocatalyst Cu-S 1 N 3 / Cu x for DFT calculations. 32 The experimental reports above suggest that sub-nanometer metal clusters can been successfully synthesized and serve as active sites in the field of electrocatalysis CO 2 ER.…”

“…The results showed that the Ni-N 4 / Ni 5 catalyst exhibited a E100% faradaic efficiency (FE CO ) toward CO 2 ER for CO from À0.4 to À0.8 V versus the reversible hydrogen electrode, superior to that of Ni-N 4 -C (FE CO = 55.0%). 24 And Meng et al developed and prepared a tandem catalyst PTF(Ni)/Cu by uniformly dispersing Cu NPs on PTF(Ni) containing atomically isolated nickel-nitrogen sites for the CO 2 electroreduction reaction to significantly enhance the production of ethylene. 25 These findings can serve as experimental and mechanistic evidence to reveal the feasibility of the design of a tandem catalyst based on Cu clusters and metal single-atom composites.…”

Integrating single atoms with nanoparticle catalysts for efficient electrochemical energy conversion

“…The existence of Ni nanoparticles (nanoclusters) can effectively accelerate the proton capture process at N-coordinated single-atom active sites (Ni-N x ), thus promoting the overall CO 2 reduction process. 204,205 In addition, Ma et al found that Mo single atoms and Mo 2 C nanoparticles exhibit synergistic catalytic activity for the nitrogen reduction reaction (NRR). 206 Theoretical calculations revealed that Mo 2 C nanoparticles are responsible for the high NRR activity, which is attributed to the Mo single atoms building a large *H coverage environment around Mo 2 C to activate the N 2 adsorption and improve both the selectivity and activity of the NRR process.…”

Size effect of nickel from nanoparticles to clusters to single atoms for electrochemical CO2 reduction

“…10,11 Despite significant efforts having been devoted to the design of nitrogen-doped-carbon-supported metal catalysts, the catalytic performance still needs to improve to meet the requirements for practical applications. 12,13 Therefore, it is urgent to develop low-cost and highly efficient catalysts for the CO 2 RR.…”