CO electroreduction on single-atom copper

Abstract

Electroreduction of carbon dioxide (CO 2 ) or carbon monoxide (CO) toward C 2+ hydrocarbons such as ethylene, ethanol, acetate and propanol represents a promising approach toward carbon-negative electrosynthesis of chemicals. Fundamental understanding of the carbon─carbon (C-C) coupling mechanisms in these electrocatalytic processes is the key to the design and development of electrochemical systems at high energy and carbon conversion efficiencies. Here, we report the investigation of CO electreduction on single-atom copper (Cu) electrocatalysts. Atomically dispersed Cu is coordinated on a carbon nitride substrate to form high-density copper─nitrogen moieties. Chemisorption, electrocatalytic, and computational studies are combined to probe the catalytic mechanisms. Unlike the Langmuir-Hinshelwood mechanism known for copper metal surfaces, the confinement of CO adsorption on the single-copper-atom sites enables an Eley-Rideal type of C-C coupling between adsorbed (*CO) and gaseous [CO(g)] carbon moxide molecules. The isolated Cu sites also selectively stabilize the key reaction intermediates determining the bifurcation of reaction pathways toward different C 2+ products.

N and OH-Immobilized Cu3 Clusters In Situ Reconstructed from Single-Metal Sites for Efficient CO2 Electromethanation in Bicontinuous Mesochannels

“…The similar reconstruction of single-atom Cu under operating CO 2 reduction conditions was elucidated in the literature. The in situ formed sites include subnanometric Cu x ( x : 2, 3, or 4) clusters − and nanoparticles with a size of ∼2–4 nm. , In contrast, many works demonstrated that carbon-supported single-atom Cu sites are electrochemically stable during the CO 2 reduction even at a negative potential of −1.6 V. − The variance is probably due to the difference in local coordination of the single-atom Cu and supports’ structure/compositions of those reported catalysts, thus leading to different single-atom Cu–support interactions that mainly determine the electrochemical stability of the single-atom Cu center. In our case, single-atom Cu was converted into a Cu 3 /Cu 4 cluster at −0.8 to −1.6 V rather than larger nanoparticles.…”

Mechanistic Implications of Low CO Coverage on Cu in the Electrochemical CO and CO2 Reduction Reactions

“…Measured reaction orders of CO in the CORR on Cu are inconsistent with the hypothesis that the coupling of two CO ad species is the RDS. Reaction orders of CO in the CORR has been determined in the H-type, , the flow-type and the membrane electrode assembly (MEA) configurations, − with highly consistent results (Table ). Formation rates of C 2+ products increase linearly at low p CO (≤0.4 atm), indicating a first order reaction.…”

Continuously Producing Highly Concentrated and Pure Acetic Acid Aqueous Solution via Direct Electroreduction of CO2

“…In this scenario, directly collecting acetic acid in a neutral environment without other solutes during an efficient eCO 2 RR process in the MEA presents a significant challenge and has not been realized so far. Instead, electrochemical CO reduction reactions (eCORR) have proven to be more effective for efficient acetate production due to the lower acidity of CO compared to CO 2 . ,− However, compared with using inexpensive CO 2 as a feedstock, the adoption of the high-purity CO gas as a reactant can substantially escalate the cost of acetate production. In light of these challenges and considerations, it is imperative to advance the development of novel electrocatalytic systems that can enhance the performance of the eCO 2 RR to yield acetic acid.…”