CO2 Reduction Reaction Selectivity Research Articles

Design of Single-Atom Co-N5 Catalytic Site: A Robust Electrocatalyst for CO2 Reduction with Nearly 100% CO Selectivity and Remarkable Stability.

We develop an N-coordination strategy to design a robust CO2 reduction reaction (CO2RR) electrocatalyst with atomically dispersed Co-N5 site anchored on polymer-derived hollow N-doped porous carbon spheres. Our catalyst exhibits high selectivity for CO2RR with CO Faradaic efficiency (FECO) above 90% over a wide potential range from -0.57 to -0.88 V (the FECO exceeded 99% at -0.73 and -0.79 V). The CO current density and FECO remained nearly unchanged after electrolyzing 10 h, revealing remarkable stability. Experiments and density functional theory calculations demonstrate single-atom Co-N5 site is the dominating active center simultaneously for CO2 activation, the rapid formation of key intermediate COOH* as well as the desorption of CO.

PH Effects on the Selectivity of the Electrocatalytic CO2 Reduction on Graphene-Embedded Fe–N–C Motifs: Bridging Concepts between Molecular Homogeneous and Solid-State Heterogeneous Catalysis

The electrochemical CO2 reduction reaction (CO2RR) is a promising route for converting CO2 and excess renewable energy into valuable chemicals and synthetic fuels. Recently, carbon-based solid materials containing dopant-levels of transition metal and nitrogen (M–N–C) have emerged as a cost-effective, energy-efficient catalyst for the direct coreduction of CO2 and H2O to CO. Fe–N–C catalysts are particularly interesting as they can reduce CO further to hydrocarbons. Despite these promising reports, the influence of the reaction conditions on the catalytic performance of Fe–N–C catalysts has not been addressed. Here, we study the role of the electrolyte on the CO2RR selectivity. Unlike hydrogen or methane generation, catalytic CO production is independent of the electrolyte pH on the normal hydrogen electrode potential scale, suggesting a decoupled elementary proton–electron transfer mechanism for CO formation. The similarity between this heterogeneous charge-transfer reaction mechanism and that of molecul...

Pd-Containing Nanostructures for Electrochemical CO2 Reduction Reaction

The electrochemical CO2 reduction reaction (CO2RR), with water as a hydrogen source, has been attracting great attention due to its promising applications for carbon recycle utilization and renewable electricity storage. In order to drive the process economically, highly efficient catalysts are urgently needed to overcome the constraints of high overpotential, low Faradaic efficiency, and current density of CO2RR. This Perspective summarizes the performance of Pd-containing nanostructures toward CO2RR and related reaction mechanisms. The product selectivity of the Pd catalysts strongly depends on the structure and composition, and the dynamic evolution of active phases induced by the applied potential and reaction intermediate of CO2RR. Introducing a second metal can effectively suppress the decay in the catalytic performance of a Pd catalyst and further improve the activity and selectivity of CO2RR. The electrochemical promotion of catalysis effect drastically improves the production rate of formate over...

Molecular Scaffolding Strategy with Synergistic Active Centers To Facilitate Electrocatalytic CO2 Reduction to Hydrocarbon/Alcohol.

A major impediment to the electrocatalytic CO2 reduction reaction (CRR) is the lack of electrocatalysts with both high efficiency and good selectivity toward liquid fuels or other valuable chemicals. Effective strategies for the design of electrocatalysts are yet to be discovered to substitute the conventional trial-and-error approach. This work shows that a combination of density functional theory (DFT) computation and experimental validation of molecular scaffolding to coordinate the metal active centers presents a new molecular-level strategy for the development of electrocatalysts with high CRR selectivity toward hydrocarbon/alcohol. Taking the most widely investigated Cu as a probe, our study reveals that the use of graphitic carbon nitride (g-C3N4) as a molecular scaffold allows for an appropriate modification of the electronic structure of Cu in the resultant Cu-C3N4 complex. As a result, the adsorption behavior of some key reaction intermediates can be optimized on the Cu-C3N4 surface, which greatly benefits the activation of CO2 and leads to a more facile CO2 reduction to desired products as compared with those on the Cu(111) surface and other kinds of Cu complexes formed on nitrogen-doped carbons. Remarkably, different from the most studied elementary metal surfaces, an intramolecular synergistic catalysis with dual active centers was for the first time observed on the Cu-C3N4 complex model, which possesses a unique capability to generate C2 products. A good agreement between electrochemical measurements and the DFT analysis of the CRR has been achieved on the basis of the newly designed and synthesized Cu-C3N4 electrocatalyst.

Single site porphyrine-like structures advantages over metals for selective electrochemical CO2 reduction

Currently, no catalysts are completely selective for the electrochemical CO2 Reduction Reaction (CO2RR). Based on trends in density functional theory calculations of reaction intermediates we find that the single metal site in a porphyrine-like structure has a simple advantage of limiting the competing Hydrogen Evolution Reaction (HER). The single metal site in a porphyrine-like structure requires an ontop site binding of hydrogen, compared to the hollow site binding of hydrogen on a metal catalyst surface. The difference in binding site structure gives a fundamental energy-shift in the scaling relation of ∼0.3eV between the COOH* vs. H* intermediate (CO2RR vs. HER). As a result, porphyrine-like catalysts have the advantage over metal catalyst of suppressing HER and enhancing CO2RR selectivity.