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Solar-driven water splitting at 13.8 % solar-to-hydrogen efficiency by an earth-abundant PV-electrolyzer
Umeå University, Faculty of Science and Technology, Department of Physics.
Umeå University, Faculty of Science and Technology, Department of Physics.ORCID iD: 0000-0002-2480-3786
Umeå University, Faculty of Science and Technology, Department of Physics.
Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.ORCID iD: 0000-0002-9732-8867
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2021 (English)In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 9, no 42, p. 14070-14078Article in journal (Refereed) Published
Abstract [en]

We present the synthesis and characterization of an efficient and low cost solar-driven electrolyzer consisting of Earth-abundant materials. The trimetallic NiFeMo electrocatalyst takes the shape of nanometer-sized flakes anchored to a fully carbon-based current collector comprising a nitrogen-doped carbon nanotube network, which in turn is grown on a carbon fiber paper support. This catalyst electrode contains solely Earth-abundant materials, and the carbon fiber support renders it effective despite a low metal content. Notably, a bifunctional catalyst–electrode pair exhibits a low total overpotential of 450 mV to drive a full water-splitting reaction at a current density of 10 mA cm–2 and a measured hydrogen Faradaic efficiency of ∼100%. We combine the catalyst–electrode pair with solution-processed perovskite solar cells to form a lightweight solar-driven water-splitting device with a high peak solar-to-fuel conversion efficiency of 13.8%.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2021. Vol. 9, no 42, p. 14070-14078
Keywords [en]
Solar-driven electrolysis, Earth-abundant materials, Nanostructured catalyst, Perovskite solar cells, Cost analysis
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:umu:diva-180129DOI: 10.1021/acssuschemeng.1c03565ISI: 000711203000009Scopus ID: 2-s2.0-85118127026OAI: oai:DiVA.org:umu-180129DiVA, id: diva2:1528342
Note

Originally included in thesis in manuscript form.

Available from: 2021-02-15 Created: 2021-02-15 Last updated: 2023-09-05Bibliographically approved
In thesis
1. Electrocatalysts for sustainable hydrogen energy: disordered and heterogeneous nanomaterials
Open this publication in new window or tab >>Electrocatalysts for sustainable hydrogen energy: disordered and heterogeneous nanomaterials
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With the current global greenhouse gas emissions, our remaining carbon budget is depleted in only 7 years. After that, several biophysical systems are predicted to collapse such as the arctic ice, coral reefs and the permafrost, leading to potentially irreversible consequences. Our emissions are strongly correlated to access of energy and even if we are aware of the planetary emergency today, our emissions still continue to grow. Electrical vehicles have the possibility to reduce the emissions in the transportation sector significantly. However, these vehicles are still expensive and impractical for long-distance or heavy transportation. While political actions and technological development are essential to keep prices down, the driving dis- tance can be increased by replacing the batteries for onboard electricity production. 

In hydrogen fuel cells, electricity is produced by combining hydrogen gas (H2) and oxygen with only water as the by-product and if employed in electrical vehicles, distances of 500 km are enabled with a refueling time in 5 minutes. For other uses than in vehicles, H2 is also promising for large-scale electricity storage and for several industrial processes such as manufacturing CO2-free steel, ammonia and synthetic fuels. However, today most H2 production methods relies on fossil fuels and releases huge amounts of CO2. 

Electrolysis of water is an alternative production method where H2, along with oxygen are produced from water. To split the water, electricity has to be added and if renewable energy sources are used, the method has zero emissions and is considered most promising for a sustainable hydrogen energy economy. The tech- nique is relatively expensive compared to the fossil fuel-based methods and relies on rare noble metals such as platinum as catalysts for decreasing the required energy to split water. For large scale productions, these metals need to be replaced by more sustainable and abundant catalysts to lower the cost and minimize the environmental impacts. 

In this thesis we have investigated such candidates for the water splitting reaction but also to some extent for the oxygen reduction reaction in fuel cells. By combining theory and experiments we hope to aid in the development and facilitate a transition to clean hydrogen energy. We find among other things that i) defects in catalytic materials plays a significant role the performance and efficiency, and that ii) heterogeneity influence the adsorption energies of reaction intermediates and hence the catalytic efficiency and iii) while defects are not often studied for electrocatalytic reactions, these may inspire for novel materials in the future. 

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2021. p. 88
Keywords
Water splitting, Electrochemistry, Nanomaterials, Density functional theory, Hydrogen evolution, MoS2, Fuel cell
National Category
Condensed Matter Physics
Research subject
nanomaterials; Physics; Physical Chemistry
Identifiers
urn:nbn:se:umu:diva-180130 (URN)978-91-7855-482-9 (ISBN)978-91-7855-481-2 (ISBN)
Public defence
2021-03-11, BIO.A.206 – Aula Anatomica, Umeå, 09:00 (English)
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Supervisors
Available from: 2021-02-18 Created: 2021-02-15 Last updated: 2021-02-16Bibliographically approved

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Ekspong, JoakimLarsen, ChristianKwong, Wai LingWang, JiaMessinger, JohannesEdman, LudvigWågberg, Thomas

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Ekspong, JoakimLarsen, ChristianKwong, Wai LingWang, JiaMessinger, JohannesEdman, LudvigWågberg, Thomas
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