Electrochemical Conversion of CO₂ to Syngas with Controllable CO/H₂ Ratios over Co and Ni Single‐Atom Catalysts

Abstract

The electrochemical CO2 reduction reaction (CO2RR) to yield synthesis gas (syngas, CO and H2) has been considered as a promising method to realize the net reduction in CO2 emission. However, it is challenging to balance the CO2RR activity and the CO/H2 ratio. To address this issue, nitrogen‐doped carbon supported single‐atom catalysts are designed as electrocatalysts to produce syngas from CO2RR. While Co and Ni single‐atom catalysts are selective in producing H2 and CO, respectively, electrocatalysts containing both Co and Ni show a high syngas evolution (total current >74 mA cm−2) with CO/H2 ratios (0.23–2.26) that are suitable for typical downstream thermochemical reactions. Density functional theory calculations provide insights into the key intermediates on Co and Ni single‐atom configurations for the H2 and CO evolution. The results present a useful case on how non‐precious transition metal species can maintain high CO2RR activity with tunable CO/H2 ratios.

Accelerating CO2 Electroreduction to CO Over Pd Single‐Atom Catalyst

“…Further stabilization of *HOCO is expected due to the formation of hydrogen bonds (0–0.15 eV/hydrogen bond) with water molecules, indicating a thermodynamically favored CO 2 RR at electrochemical conditions compared to gas‐phase DFT calculated energetics. [ 36–39 ] Additionally, the desorption of weakly bound *CO (BE = −0.02 eV) is predicted to be significantly facilitated on PdN 4 compared to Pd/PdH. Therefore, in agreement with the experimental observations, DFT predicts an enhanced CO 2 RR on PdN 4 single‐atom site compared to Pd/PdH and Pd nanoparticles supported on graphene.…”

Nanostructures for Electrocatalytic CO2 Reduction

“…DFT results indicate that the formation of *COOH is the rate‐limiting step, and the Zn‐N 4 single atoms work as the active site for ECR and decrease the energy barrier [77] . Chen and co‐workers developed a nitrogen‐doped carbon supported Ni and Co single‐atom catalyst (CoNi‐NC) as an ECR catalyst [78] . The as‐prepared CoNi‐NC shows high catalytic activity (total current density >74 mA cm −2 at a potential of −1.0 V vs. RHE) and tunable CO/H 2 ratios (0.23–3.26).…”

POM‐Incorporated CoO Nanowires for Enhanced Photocatalytic Syngas Production from CO2

“…[26][27][28] Recently, Co single atom catalysts have been demonstrated high activity towards photocatalysis and electrochemical syngas production. [29][30][31] Through reviewing the published works, we found that the research on amorphous Co-based compounds remains deficient. Besides, the simultaneous high-efficiency evolution of syngas is still challenging.…”