skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Electrolyte Anions Suppress Hydrogen Generation in Electrochemical CO Reduction on Cu
Abstract In this study, we employed electrochemical‐mass spectrometry (EC‐MS) to elucidate the role of halide anions in electrochemical CO2and CO reduction. We found that the undesired hydrogen evolution reaction (HER) was significantly suppressed by the anion used. Specifically, the rates of H2production decreased in the order KF > KCl > KI, meaning that I−most strongly suppressed HER. Interestingly, CO reduction products showed an inverse relationship to HER, with KI leading to the highest rate of CO reduction. By pairing our experimental findings with classical molecular dynamics simulations, we propose a mechanism wherein halide anions influence the dynamic interplay between CO reduction and HER by modulating the competition of H* and CO* for active sites on the Cu surface. We propose that this interaction is enabled by the interfacial concentration of K+being greater in the presence of F−than in I−. Our results highlight the need to more broadly consider the properties of ions at electrocatalytic interfaces and they point to thus far underappreciated avenues to optimize hydrocarbon production while suppressing hydrogen evolution.  more » « less
Award ID(s):
2245375
PAR ID:
10565854
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Angewandte Chemie International Edition
Volume:
64
Issue:
10
ISSN:
1433-7851
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; (, Angewandte Chemie International Edition)
    Abstract Electrochemical CO2reduction (CO2RR) on copper (Cu) shows promise for higher‐value products beyond CO. However, challenges such as the limited CO2solubility, high overpotentials, and the competing hydrogen evolution reaction (HER) in aqueous electrolytes hinder the practical realization. We propose a functionalized ionic liquid (IL) which generates ion‐CO2adducts and a hydrogen bond donor (HBD) upon CO2absorption to modulate CO2RR on Cu in a non‐aqueous electrolyte. As revealed by transient voltammetry, electrochemical impedance spectroscopy (EIS), and in situ surface‐enhanced Raman spectroscopy (SERS) complemented with image charge augmented quantum‐mechanical/molecular mechanics (IC‐QM/MM) computations, a unique microenvironment is constructed. In this microenvironment, the catalytic activity is primarily governed by the IL and HBD concentrations; former controlling the double layer thickness and the latter modulating the local proton availability. This translates to ample CO2availability, reduced overpotential, and suppressed HER where C4products are obtained. This study deepens the understanding of electrolyte effects in CO2RR and the role of IL ions towards electrocatalytic microenvironment design. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, Nature Communications)
    Abstract Copper-based catalyst is uniquely positioned to catalyze the hydrocarbon formations through electrochemical CO2reduction. The catalyst design freedom is limited for alloying copper with H-affinitive elements represented by platinum group metals because the latter would easily drive the hydrogen evolution reaction to override CO2reduction. We report an adept design of anchoring atomically dispersed platinum group metal species on both polycrystalline and shape-controlled Cu catalysts, which now promote targeted CO2reduction reaction while frustrating the undesired hydrogen evolution reaction. Notably, alloys with similar metal formulations but comprising small platinum or palladium clusters would fail this objective. With an appreciable amount of CO-Pd1moieties on copper surfaces, facile CO*hydrogenation to CHO*or CO-CHO*coupling is now viable as one of the main pathways on Cu(111) or Cu(100) to selectively produce CH4or C2H4through Pd-Cu dual-site pathways. The work broadens copper alloying choices for CO2reduction in aqueous phases. 
    more » « less
  3. ; ; ; ; ; ; (, Angewandte Chemie International Edition)
    Abstract To explore the structure–function relationships of cobalt complexes in the catalytic hydrogen evolution reaction (HER), we studied the substitution of a tertiary amine with a softer pyridine group and the inclusion of a conjugated bpy unit in a Co complex with a new pentadentate ligand, 6‐[6‐(1,1‐di‐pyridin‐2‐yl‐ethyl)‐pyridin‐2‐ylmethyl]‐[2,2′]bipyridinyl (Py3Me‐Bpy). These modifications resulted in significantly improved stability and activity in both electro‐ and photocatalytic HER in neutral water. [Co(Py3Me‐Bpy)(OH2)](PF6)2catalyzes the electrolytic HER at −1.3 V (vs. SHE) for 20 hours with a turnover number (TON) of 266 300, and photolytic HER for two days with a TON of 15 000 in pH 7 aqueous solutions. The softer ligand scaffold possibly provides increased stability towards the intermediate CoIspecies. DFT calculations demonstrate that HER occurs through a general electron transfer/proton transfer/electron transfer/proton transfer pathway, with H2released from the protonation of CoII−H species. 
    more » « less
  4. ; (, Chemical Science)
    Electrochemical conversion of CO 2 into value-added chemicals continues to draw interest in renewable energy applications. Although many metal catalysts are active in the CO 2 reduction reaction (CO 2 RR), their reactivity and selectivity are nonetheless hindered by the competing hydrogen evolution reaction (HER). The competition of the HER and CO 2 RR stems from the energy scaling relationship between their reaction intermediates. Herein, we predict that bimetallic monolayer electrocatalysts (BMEs) – a monolayer of transition metals on top of extended metal substrates – could produce dual-functional active sites that circumvent the scaling relationship between the adsorption energies of HER and CO 2 RR intermediates. The antibonding interaction between the adsorbed H and the metal substrate is revealed to be responsible for circumventing the scaling relationship. Based on extensive density functional theory (DFT) calculations, we identify 11 BMEs which are highly active and selective toward the formation of formic acid with a much suppressed HER. The H–substrate antibonding interaction also leads to superior CO 2 RR performance on monolayer-coated penta-twinned nanowires. 
    more » « less
  5. ; ; ; ; ; ; ; ; (, Advanced Energy Materials)
    Abstract Aqueous zinc metal batteries (AZMB) are emerging as a promising alternative to the prevailing existing Lithium‐ion battery technology. However, the development of AZMBs is hindered due to challenges including dendrite formation, hydrogen evolution reaction (HER), and ZnO passivation on the anode. Here, a tetraalkylsulfonamide (TAS) additive for suppressing HER, dendrite formation, and enhancing cyclability is rationally designed. Only 1 mmTAS is found that can effectively displace water molecules from the Zn2+solvation shell, thereby altering the solvation matrix of Zn2+and disrupting the hydrogen bond network of free water, as demonstrated through67 Zn and1H nuclear magnetic resonance spectroscopy, high‐resolution mass spectrometry (HRMS), and density functional theory (DFT) studies. Voltammetry synchronized with in situ monitoring of the electrode surface reveals suppressed dendritic growth and HER in the presence of TAS. Electrochemical mass spectrometry (ECMS) captures real‐time HER suppression during Zn electrodeposition, revealing the ability of TAS to suppress the HER by an order of magnitude. A ≈25‐fold cycle life improvement from ≈100 h to over 2500 h in coin cells cycled in the presence of TAS. Furthermore, by suppressing passivation product formation, it is demonstrated that strategy robustly maximizes the stability of Zn metal anodes. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email