Sustainable synthesis through electrocatalysis

Multi-metal electrocatalysis - Controlling the mechanistic pathways for electrochemical CO₂ reduction

Research Topics
Methods
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The Electrochemical Conversion of CO₂ group is researching how carbon dioxide and water can be converted electrochemically into hydrocarbons such as methane and methanol using renewable energies.

Presently, most carbon-based fuels and industrial chemicals originate from fossil resources accumulated over millions of years. Following their use, these fuels and chemicals decompose to CO₂ which is released into our atmosphere, causing significant changes to global climate.

We envision an alternative, more sustainable approach -- using CO₂ as carbon source and driving its conversion back into useful chemicals using renewable electricity. Many important and valuable chemicals could be produced this way, including syngas (CO+H₂), methane, ethylene, ethanol, and other C₂₊ products. But numerous challenges in product selectivity, conversion efficiency, and reaction rates must first be overcome, necessitating efforts in research and development.

The research group takes multiple approaches to overcoming these challenges, including designing new catalysts, studying structure-function relationships using in situ spectroscopic methods, developing flow reactors, and investigating the ability of light to influence reactions.

Research Topics

Structure activity relationsship for bi-metallic catalysts

Structure–activity relationships in bi-metallic catalysts

Our goal is to electrochemically convert CO₂ to highly-reduced, valuable organic products (alkanes, alkenes, alcohols) in a single process. Individual metal catalysts suffer from binding energy scaling, which impart thermodynamic barriers and result in low efficiency and poor yield of the desired products. We will examine the ability of multi-metal catalysts to enable different binding modes and reaction mechanisms which favor the production of highly-reduced products.

Targeting kinetic limitations via advanced cell design

The low solubility of CO₂ in water limits conventional systems to low current densities. For the technology to be industrially viable, much higher rates of CO₂ transport are necessary, and this can be achieved by using gas diffusion cells. Our research efforts involve synthesis of robust membrane–electrode assemblies suited for electrochemical CO₂ reduction, and design of cells capable of efficient product collection.

Mechanism study using operando spectroscopy

Improved understanding of electrochemical mechanisms is needed to enable design of better catalysts. We are developing methods for spectroscopic analysis of catalysts under real operation conditions. This includes design of an electrochemical cell for X-ray emission/absorption and photoelectron spectroscopy.

Methods

Electrochemical mass spectrometry
By interfacing an electrochemical cell with a mass spectrometer via a pervaporation membrane, dissolved volatile products can be detected and identified by mass fragments almost instantaneously during electrocatalyst testing. This enables, for example, the determination of potential-dependent product formation across the whole potential range during a single linear sweep voltammetry experiment.
Reference: Clark, E. L., et al. Differential Electrochemical Mass Spectrometer Cell Design for Online Quantification of Products Produced during Electrochemical Reduction of CO₂. Anal. Chem. 2015, 87 (15), 8013–8020.

Electrochemical workstations
We use potentiostat/galvanostat instruments to perform the whole range of electrochemical experiments.

Gas chromatography
Gas outflow from the cell is separated and quantified by gas chromatography (GC), enabling precise quantification for Faradaic efficiency determinations. Products measured include carbon monoxide, hydrogen, oxygen, methane, ethylene, and other gaseous hydrocarbons.
A separate autosampler channel allows automated sampling of liquid vials for volatile liquids determination (alcohols, aldehydes).

Fume hood
A tall fume hood equipped with carbon monoxide sensors allows experiments in CO reduction.

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Vacancies

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Electrochemical Conversion of CO₂