Browse
Submit Data
Databases
API
Help

Dataset Information

14 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Fast CO₂ hydration kinetics impair heterogeneous but improve enzymatic CO₂ reduction catalysis.

ABSTRACT: The performance of heterogeneous catalysts for electrocatalytic CO₂ reduction suffers from unwanted side reactions and kinetic inefficiencies at the required large overpotential. However, immobilized CO₂ reduction enzymes-such as formate dehydrogenase-can operate with high turnover and selectivity at a minimal overpotential and are therefore 'ideal' model catalysts. Here, through the co-immobilization of carbonic anhydrase, we study the effect of CO₂ hydration on the local environment and performance of a range of disparate CO₂ reduction systems from enzymatic (formate dehydrogenase) to heterogeneous systems. We show that the co-immobilization of carbonic anhydrase increases the kinetics of CO₂ hydration at the electrode. This benefits enzymatic CO₂ reduction-despite the decrease in CO₂ concentration-due to a reduction in local pH change, whereas it is detrimental to heterogeneous catalysis (on Au) because the system is unable to suppress the H₂ evolution side reaction. Understanding the role of CO₂ hydration kinetics within the local environment on the performance of electrocatalyst systems provides important insights for the development of next-generation synthetic CO₂ reduction catalysts.

SUBMITTER: Cobb SJ

PROVIDER: S-EPMC7612589 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Comparing interfacial cation hydration at catalytic active sites and spectator sites on gold electrodes: understanding structure sensitive CO2 reduction kinetics.

Project description:Hydrated cations present in the electrochemical double layer (EDL) are known to play a crucial role in electrocatalytic CO2 reduction (CO2R), and numerous studies have attempted to explain how the cation effect contributes to the complex CO2R mechanism. CO2R is a structure sensitive reaction, indicating that a small fraction of total surface sites may account for the majority of catalytic turnover. Despite intense interest in specific cation effects, probing site-specific, cation-dependent solvation structures remains a significant challenge. In this work, CO adsorbed on Au is used as a vibrational Stark reporter to indirectly probe solvation structure using vibrational sum frequency generation (VSFG) spectroscopy. Two modes corresponding to atop adsorption of CO are observed with unique frequency shifts and potential-dependent intensity profiles, corresponding to direct adsorption of CO to inactive surface sites, and in situ generated CO produced at catalytic active sites. Analysis of the cation-dependent Stark tuning slopes for each of these species provides estimates of the hydrated cation radius upon adsorption to active and inactive sites on the Au electrode. While cations are found to retain their bulk hydration shell upon adsorption at inactive sites, catalytic active sites are characterized by a single layer of water between the Au surface and the electrolyte cation. We propose that the drastic increase in catalytic performance at active sites stems from this unique solvation structure at the Au/electrolyte interface. Building on this evidence of a site-specific EDL structure will be critical to understand the connection between cation-dependent interfacial solvation and CO2R performance.

| S-EPMC9242014 | biostudies-literature

Electrochemical promotion of catalysis over Pd nanoparticles for CO2 reduction.

Project description:Electrochemical promotion of catalysis (EPOC) has been shown to accelerate the rate of many heterogeneous catalytic reactions; however, it has rarely been reported in low-temperature aqueous electrochemical reactions. Herein, we report a significant EPOC effect for the CO2 reduction to generate formate over Pd nanoparticles (NPs) in a 1 M KHCO3 aqueous solution. By applying a negative potential over differently-sized Pd NPs, the rate of formate production is greatly improved as compared to that at an open-circuit voltage, with a rate enhancement ratio ranging from 10 to 143. The thermocatalytic and electrocatalytic reduction of CO2 compete with each other and are promoted by the applied negative potential and H2 in the feeds, respectively. Inspired by the EPOC effect, a composite electrode containing Pd/C and Pt/C catalysts on different sides of a carbon paper was constructed for catalyzing the CO2 reduction without adding H2 to the feeds. Water electrolysis over Pt NPs generates H2, which then effectively promotes formate production over Pd NPs.

| S-EPMC5431665 | biostudies-literature

Magnetic Co-Doped MoS2 Nanosheets for Efficient Catalysis of Nitroarene Reduction.

Project description:Co-doped MoS2 nanosheets have been synthesized through the hydrothermal reaction of ammonium tetrathiomolybdate and hydrazine in the presence of cobalt acetate. These nanosheets exhibit a dominant metallic 1T phase with cobalt ion-activated defective basal planes and S-edges. In addition, the nanosheets are dispersible in polar solvents like water and methanol. With increased active sites, Co-doped MoS2 nanosheets exhibit exceptional catalytic activity in the reduction of nitroarenes by NaBH4 with impressive turnover frequencies of 8.4, 3.2, and 20.2 min-1 for 4-nitrophenol, 4-nitroaniline, and nitrobenzene, respectively. The catalyst is magnetic, enabling its easy separation from the reaction mixture, thus making its recycling and reusability simple and efficient. The enhanced catalytic activity of the Co-doped 1T MoS2 nanosheets in comparison to that of undoped 1T MoS2 nanosheets suggests that incorporation of cobalt ions in the MoS2 lattice is the major reason for the efficiency of the catalyst. The dopant, Co, plays a dual role. In addition to providing active sites where electron transfer is assisted through redox cycling, it renders the nanosheets magnetic, enabling their easy removal from the reaction mixture.

| S-EPMC6644400 | biostudies-literature

Heterogeneous Epoxide Carbonylation by Cooperative Ion-Pair Catalysis in Co(CO)4--Incorporated Cr-MIL-101.

Project description:Despite the commercial desirability of epoxide carbonylation to ?-lactones, the reliance of this process on homogeneous catalysts makes its industrial application challenging. Here we report the preparation and use of a Co(CO)4--incorporated Cr-MIL-101 (Co(CO)4?Cr-MIL-101, Cr-MIL-101 = Cr3O(BDC)3F, H2BDC = 1,4-benzenedicarboxylic acid) heterogeneous catalyst for the ring-expansion carbonylation of epoxides, whose activity, selectivity, and substrate scope are on par with those of the reported homogeneous catalysts. We ascribe the observed performance to the unique cooperativity between the postsynthetically introduced Co(CO)4- and the site-isolated Lewis acidic Cr(III) centers in the metal-organic framework (MOF). The heterogeneous nature of Co(CO)4?Cr-MIL-101 allows the first demonstration of gas-phase continuous-flow production of ?-lactones from epoxides, attesting to the potential applicability of the heterogeneous epoxide carbonylation strategy.

| S-EPMC5445536 | biostudies-literature

Constructing asymmetric double-atomic sites for synergistic catalysis of electrochemical CO2 reduction.

Project description:Elucidating the synergistic catalytic mechanism between multiple active centers is of great significance for heterogeneous catalysis; however, finding the corresponding experimental evidence remains challenging owing to the complexity of catalyst structures and interface environment. Here we construct an asymmetric TeN2-CuN3 double-atomic site catalyst, which is analyzed via full-range synchrotron pair distribution function. In electrochemical CO2 reduction, the catalyst features a synergistic mechanism with the double-atomic site activating two key molecules: operando spectroscopy confirms that the Te center activates CO2, and the Cu center helps to dissociate H2O. The experimental and theoretical results reveal that the TeN2-CuN3 could cooperatively lower the energy barriers for the rate-determining step, promoting proton transfer kinetics. Therefore, the TeN2-CuN3 displays a broad potential range with high CO selectivity, improved kinetics and good stability. This work presents synthesis and characterization strategies for double-atomic site catalysts, and experimentally unveils the underpinning mechanism of synergistic catalysis.

| S-EPMC10547798 | biostudies-literature

Integrated Cobaloxime and Mesoporous Silica-Supported Ruthenium/Diamine Co-Catalysis for One-Pot Hydration/Reduction Enantioselective Sequential Reaction of Alkynes.

Project description:This study developed a cost-efficient hydration/asymmetric transfer hydrogenation (ATH) process for the one-pot synthesis of valuable chiral alcohols from alkynes. During this process, the initial homogeneous cobaloxime-catalyzed hydration of alkynes was followed by heterogeneous Ru/diamine-catalyzed ATH transformation of the in-situ generated ketones, which provided varieties of chiral alcohols in good yields with up to 99% ee values. The immobilized Ru/diamine catalyst could be recycled at least three times before its deactivation in the sequential reaction system. This work shows a general method for developing one-pot asymmetric sequential catalysis towards sustainable organic synthesis.

| S-EPMC8493125 | biostudies-literature

Conformational Change of H64 and Substrate Transportation: Insight Into a Full Picture of Enzymatic Hydration of CO2 by Carbonic Anhydrase.

Project description:The enzymatic hydration of CO2 into HCO3 - by carbonic anhydrase (CA) is highly efficient and environment-friendly measure for CO2 sequestration. Here extensive MM MD and QM/MM MD simulations were used to explore the whole enzymatic process, and a full picture of the enzymatic hydration of CO2 by CA was achieved. Prior to CO2 hydration, the proton transfer from the water molecule (WT1) to H64 is the rate-limiting step with the free energy barrier of 10.4 kcal/mol, which leads to the ready state with the Zn-bound OH-. The nucleophilic attack of OH- on CO2 produces HCO3 - with the free energy barrier of 4.4 kcal/mol and the free energy release of about 8.0 kcal/mol. Q92 as the key residue manipulates both CO2 transportation to the active site and release of HCO3 -. The unprotonated H64 in CA prefers in an inward orientation, while the outward conformation is favorable energetically for its protonated counterpart. The conformational transition of H64 between inward and outward correlates with its protonation state, which is mediated by the proton transfer and the product release. The whole enzymatic cycle has the free energy span of 10.4 kcal/mol for the initial proton transfer step and the free energy change of -6.5 kcal/mol. The mechanistic details provide a comprehensive understanding of the entire reversible conversion of CO2 into bicarbonate and roles of key residues in chemical and nonchemical steps for the enzymatic hydration of CO2.

| S-EPMC8299336 | biostudies-literature

The mechanism for CO2 reduction over Fe-modified Cu(100) surfaces with thermodynamics and kinetics: a DFT study.

Project description:The adsorption, activation and reduction of CO2 over Fe x /Cu(100) (x = 1-9) surfaces were examined by density functional theory. The most stable structure of CO2 adsorption on the Fe x /Cu(100) surface was realized. The electronic structure analysis showed that the doped Fe improved the adsorption, activation and reduction of CO2 on the pure Cu(100) surface. From the perspective of thermodynamics and kinetics, the Fe4/Cu(100) surface acted as a potential catalyst to decompose CO2 into CO with a barrier of 32.8 kJ mol-1. Meanwhile, the first principle molecular dynamics (FPMD) analysis indicated that the decomposition of the C-O1 bond of CO2 on the Fe4/Cu(100) surface was only observed from 350 K to 450 K under a CO2 partial pressure from 0 atm to 10 atm. Furthermore, the results of FPMD analysis revealed that CO2 would rather decompose than hydrogenate when CO2 and H co-adsorbed on the Fe4/Cu(100) surface.

| S-EPMC9056627 | biostudies-literature

Ultrasound-boosted selectivity of CO in CO2 electrochemical reduction.

Project description:Among the possible products of CO2 electrochemical reduction, CO plays a unique and vital role, which can be an ideal feedstock for further reduction to C2+ products, and also the important component of syngas that can be used as feedstock for value-added chemicals and fuels. However, it is still a challenge to tune the CO selectivity on Cu electrode. Here we newly construct an ultrasound-assisted electrochemical method for CO2 reduction, which can tune the selectivity of CO2 to CO from less than 10% to >80% at -1.18 V versus (vs.) reversible hydrogen electrode (RHE). The partial current density of CO production is significantly improved by 15 times. By in-situ Raman study, the dominating factor for the improved CO production is attributed to the accelerated desorption of *CO intermediate. This work provides a facile method to tune the product selectivity in CO2 electrochemical reduction.

| S-EPMC8213958 | biostudies-literature

Light-Driven CO2 Reduction by Co-Cytochrome b 562.

Project description:The current trend in atmospheric carbon dioxide concentrations is causing increasing concerns for its environmental impacts, and spurring the developments of sustainable methods to reduce CO2 to usable molecules. We report the light-driven CO2 reduction in water in mild conditions by artificial protein catalysts based on cytochrome b 562 and incorporating cobalt protoporphyrin IX as cofactor. Incorporation into the protein scaffolds enhances the intrinsic reactivity of the cobalt porphyrin toward proton reduction and CO generation. Mutations around the binding site modulate the activity of the enzyme, pointing to the possibility of further improving catalytic activity through rational design or directed evolution.

| S-EPMC8082397 | biostudies-literature