Nanoparticle-Assisted Ni–Co Binary Single-Atom Catalysts Supported on Carbon Nanotubes for Efficient Electroreduction of CO₂ to Syngas with Controllable CO/H₂ Ratios

Abstract

Electrochemical conversion of CO2 to the syngas hybrid with the Fischer–Tropsch (FT) process is a promising way to produce synthetic fuels from renewable energy sources. The product distribution in liquid hydrocarbons produced by FT synthesis has strong dependence on the CO/H2 ratio of the syngas feedstock. Herein, we demonstrated the feasibility of tuning the CO/H2 ratio at a wide range by developing nanoparticle-assisted Ni–Co binary single-atom catalysts for electrocatalytic production of syngas. By controlling the elemental proportion of Ni–Co in the composite catalysts, electrochemical reduction of CO2 to syngas with a tunable CO/H2 ratio from 0.3 to 27.6 was achieved. For the binary catalysts with a Ni–Co ratio of 1:1, the CO/H2 ratio maintains at 1.3–1.5 in a broad potential range from −0.59 to −0.83 V versus reversible hydrogen electrode (RHE) and the total current density reaches ∼32.2 mA/cm2 at −1.0 V versus RHE. The promotion effect of nanoparticles on Ni–Co single-atom catalysts was validated by partial removal of nanoparticles and further density functional theory (DFT) calculations. As revealed by DFT calculations, nanoparticles incorporated in single-atom sites take essential roles in facilitating the adsorption of CO2 and the formation of *COOH. The origin of CO2RR and hydrogen evolution reaction reactivities can be identified as Ni–N4 and Co–N4 single-atom sites, respectively. The dual active sites allow the facile control of the CO/H2 ratio of electrochemical converted syngas, and it will be beneficial to downstream production of diverse chemicals.

Synergetic Dual‐Atom Catalysts: The Next Boom of Atomic Catalysts

“…realized the wide‐range regulation of H 2 /CO from 0.3 to 27.6 by changing the ratio of Co and Ni. Theoretical calculation found that Ni‐N 4 was favorable for CO desorption, while Co‐N 4 was HER‐selective [110] . In addition to directly acting as the active sites, the second metal atom may also influence the surrounding N species and change the CO 2 RR and HER trends.…”

“…Theoretical calculation found that Ni-N 4 was favorable for CO desorption, while Co-N 4 was HER-selective. [110] In addition to directly acting as the active sites, the second metal atom may also influence the surrounding N species and change the CO 2 RR and HER trends. In BiÀ Zn DAC recently reported by Meng et al, the CO/H 2 ratios generated from electrocatalytic CO 2 RR of BiZn/ NC-1, BiZn/NC-2, and BiZn/NC-3 were 0.51-2.92, 0.20-1.92, and 0.34-1.42, respectively.…”

Research progress of asymmetrically coordinated single-atom catalysts for electrocatalytic reactions

“…M 1 -N 4 and M 2 -N 4 active site doping and M 1 M 2 -N x catalysts with M 1 -M 2 metal bonds are the two main forms of heteronuclear bimetallic site catalysts, which have been extensively studied in the eld of electrocatalysis. [112][113][114][115][116] With the aid of the metal organic framework, a Ni/Cu dual-site catalyst with well-dened coordination was successfully synthesized. The synergistic effect of adjacent Ni-N 4 and Cu-N 4 active sites can adjust the distribution of electrons and reduce the band gap and the overall potential barrier of the CO 2 RR, resulting in remarkable catalytic performance.…”

Temperature-Controlled Syngas Production via Electrochemical CO2 Reduction on a CoTPP/MWCNT Composite in a Flow Cell

“…Along with the catalyst design, most of the approaches have also focused on investigating the applied potential for controlling the syngas H 2 /CO ratio. 20 − 22 …”