Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - HY-CAT (Multifunctional Hybrid Platforms based on Colloidal Nanocrystals to Advance CO2 Conversion Studies )

Teaser

In reimagining the world’s energy future, while researchers are seeking alternative ways to produce energy, our current dependence on fossil fuels requires us to capture and store the CO2 to prevent reaching unacceptable CO2 levels in the atmosphere. In this scenario...

Summary

In reimagining the world’s energy future, while researchers are seeking alternative ways to produce energy, our current dependence on fossil fuels requires us to capture and store the CO2 to prevent reaching unacceptable CO2 levels in the atmosphere. In this scenario, recycling CO2 by converting it into useful chemicals represents an important research area as it will eventually lead to independence from fossil fuels and petroleum. While much progress has been made, this emerging field is still challenged by many technical and scientific questions.
The reaction of CO2 with protons from water can generate a variety of valuable products, such as liquid fuels for transportation. However, CO2 is a very stable molecule, thus efficient catalysts to break its bonds are needed. These catalysts need to be selective when forming new bonds between carbon, oxygen and hydrogen in order to target one specific combination of these and, thus, one specific final product. The rules of design for efficient and selective CO2 reduction electrocatalysts are yet to be known.
In Hy-Cat, we synthesize hybrid catalytic platforms comprising different functionalities intimately bound in one single integrated catalyst. We combine atomically precise metallic nanoparticles with porous, ceramic and organic materials with the ultimate goal to find better catalysts to convert CO2 into value added chemicals while storing renewable energies.

Work performed

Hy-Cat is carried out by an excellent team of young and motivated researchers with expertise spanning from molecular and material chemistry to electrochemistry and device engineering. During this first period, we learned how to synthesize hybrid electrocatalysts including silver nanoparticles embedded in a thin porous layer of the so-called metal-organic frameworks. We have discovered that this layer makes the nanoparticles more selective for CO2 reduction and also more stable towards aggregation during catalysis. Changes of the silver electronic structure together with mass trasport effect were found to generate such improvement. We were also able to combine copper nanoparticles in an intimate junction with ceria oxide nanoparticles in a structure defined as heterodimers. Taking advantages of the versatility offered by colloidal chemistry, we could tune the size of the copper domain so to change the extension of the interface and to study its effect on the catalytic properties. We found that the interface between copper and ceria makes copper more selective towards reducting CO2 to methane. With the help of theory, we explain this result with the formation of oxygen vacancies in the ceria which helps to steer the reaction pathway. With this new acquired knowledge, we are now exploring other oxides aiming at methanol and ethanol production. Finally, we have designed and built a state-ot-the-art electrochemical cell where CO2 is fed directly as a gas, instead of being dissolved in water. This device allows us to test the catalysts under commercially relevant conditions, a step which is crucial to the technological development needed to make actual progress towards sustainability.

Final results

Hy-Cat has the ambitious goal to contribute to defining the rules for more active, selective and stable catalysts for the electrochemical conversion of CO2. State-of-the-art is represented by copper metal, yet a foil of copper produces 16 different products from CO2. We are demonstrating that tuning the size and the shape of copper and constructing interfaces with materials of different chemical nature aid copper to gain selectivity towards one specific product. Looking to the future, we hope to demonstrate that long term stability can be achieved so that a technology based on electrochemical CO2 recycling will become closer to be a reality.

Website & more info

More info: https://www.epfl.ch/labs/lnce/.