Nanostructured metal oxides for solar fuels

Lead Research Organisation: University of Bath
Department Name: Chemical Engineering

Abstract

The Sun could potentially supply enough energy for all our needs, but its energy needs to be harvested and stored efficiently. A sustainable route to capture energy from the Sun involves using photocatalytic materials that, upon solar irradiation, rearrange the electrons in molecules such as water and carbon dioxide and consequently form fuels such as hydrogen and hydrocarbons and harmless oxygen. This route, typically called artificial photosynthesis, has the potential to ensure affordable supplies of clean fuels and feedstocks for energy, pharmaceuticals, plastics and textiles, simply using inexhaustible resources.

The aim of this project is to make a breakthrough in the synthesis of metal oxides with tailored nanostructure to improve the efficiency and competitiveness of artificial photosynthesis devices in the formation of clean fuels such as hydrogen. In order to achieve this, graphene oxide flakes, carbon mats known for its nano and two-dimensionality, will be systematically studied as a sacrificial support for the formation of metal oxide nanoflakes replicating the graphene oxide shape. This will lead to a more optimised morphology to exploit the qualities of metal oxides in artificial photosynthesis.

The project will follow a multidisciplinary approach involving the undertaking of different activities, namely wet chemical syntheses, devices construction and advanced characterisation to achieve its aim. Each of these activities will address a different challenge. Through wet chemical syntheses, the project will aim to understand the mechanisms to replicate the nano- and two-dimensionality of graphene oxide on metal oxides. The second activity will concentrate on finding the best routes to apply the novel metal oxides for solar fuels production. The third activity will have the challenge of characterising the photocatalytic nanostructured materials in such a way to relate their properties to their activity, allowing the optimisation of the devices.

Preparing metal oxides with nano- and two-dimensionality as in graphene oxide will have a considerable impact on the research of these materials and on their application. This will ensure important advances towards a more sustainable
energy mix of clean energy for current and future generations.

Planned Impact

This project will research for the first time both (1) the formation of a family of nanostructured metal oxides using graphene oxide as a sacrificial support and (2) their application in hydrogen fuel generation using solar irradiation. This is particularly important, since the world energy use is predicted to increase from 19 TW in 2015 to 27 TW by 2040 and carbon dioxide emissions from fossil fuel consumption need to be significantly reduced to address global warming. Although academics conducting research in the renewable energy and catalysis sector will be the primary beneficiaries of this research, the outcomes of this project are also likely to have an impact in a near future on the fine chemical industry, which requires catalysts with optimised surface area and morphology. More broadly, the results of this research aim to contribute towards a more sustainable society and cleaner and healthier environment.

Companies will benefit from the novel protocols researched to prepare nanostructured catalysts in this project because these materials will offer much higher performances in applications such as solar hydrogen production. In addition to contributing towards the creation of more efficient devices that use clean energy, there will also be opportunities to apply the novel materials in other technologies such as car catalytic converters and pharmaceutics syntheses. To ensure companies are aware of and benefit from this research, we will exploit the events organised by the Centres for Doctoral Training (CDT) in Catalysis and in Sustainable Chemical Technologies, which companies in the renewable energy and catalysis sectors regularly attend. For example, every summer within the CDT in Sustainable Chemical Technologies a Summer Showcase is organised by the CDT members and affiliates, where the research is presented and discussed among academics and members of the industry. Conferences and seminars where industry regularly participate such as the UK Catalysis Conference 2018 will also be used for dissemination and engagement with industry. Filing patent applications with the research inventions of this project will ensure the intellectual property is identified and protected for future commercialisation.

The general public will benefit from this research with next generation materials that produce hydrogen fuel from simply sun and water, diversifying the energy portfolio. The researchers of this proposal will participate in public engagement activities, including the Bath Science Café and the Bath Taps into Science, to engage with a wider audience. The Bath Science Café is a monthly event where researchers can informally explain the latest ideas in science and technology and debate the topics. The Bath Taps into Science is a science festival happening in March every year, with multiple stands covering most of research areas at University of Bath. Newsletters, magazines and press media will also be used (in addition to peer-reviewed scientific journals) to approach a more general audience. In addition to the University of Bath online communication resources such as its website and e-newsletter, a more specific group website will be set up where videos, posters and highlights will regularly be uploaded.
 
Description This project has generated significant new knowledge on the preparation of photoanodes for solar water splitting, an important technology that has the potential to produce clean fuels such as hydrogen using inexhaustible sources such as water and sun. For example, we have discovered a simple strategy to prepare photoanodes made of hematite (that is rust) with simultaneous formation of an electrocatalyst on its pore surfaces, this way boosting photocurrents associated with the water splitting. We have also found that hematite precursors can be prepared with deep eutectic solvents, which are much greener and cheaper than organic solvents.

Our methodologies have also found applications in other fields. We have for example discovered that we can use graphene oxide as a sacrificial template of cerium oxide, widely used in car catalytic converters. Graphene oxide has a two-dimensional shape and this shape is replicated in final cerium oxide, making it much more active in the abatement of engine exhaust carbon monoxide fumes. It also worked much better as a support of nickel particles for the conversion of biogas to more useful gases that could be used in chemical plants or as fuels.

More details can be found in the following publications:

• Simultaneous Formation of FeOx Electrocatalyst Coating within Hematite Photoanodes for Solar Water Splitting. ACS Applied Energy Materials, 2019

• Enhanced ceria nanoflakes using graphene oxide as a sacrificial template for CO oxidation and dry reforming of methane. Applied Catalysis B: Environmental, 2019

• Mo-doped TiO2 photoanodes using [Ti4Mo2O8(OEt)10]2 bimetallic oxo cages as a single source precursor, Sustainable Energy & Fuels, 2018

• Park M, Walsh D, Zhang J, Kim J, Eslava S. (2018). Efficient hematite photoanodes prepared by hydrochloric acid-treated solutions with amphiphilic graft copolymer, Journal of Power Sources, 2018

• Microwave-assisted deep eutectic-solvothermal preparation of iron oxide nanoparticles for photoelectrochemical solar water splitting. J. Mater. Chem. A, 2017

• Exploring effects of intermittent light upon visible light promoted water oxidations. Sustainable Energy & Fuels, 2017

• Nanostructured WO photoanodes for efficient water splitting via anodisation in citric acid . RSC Advances, 2017


This project has also contributed to the training of students and researchers in solar technologies and nanotechnology. They have developed their research, communication and management skills, progressing in their careers and making them more qualified for academia and industry jobs. It has also contributed to generate research capabilities on solar technologies that
Exploitation Route This project has worked towards the fundamental understanding of how nanostructured metal oxides can be prepared using sacrificial templates and others, establishing models that can be exported to many metal oxides. Therefore this research is primarily impacting on academics at national and international level working with metal oxides in the broad fields of catalysis, photovoltaics, nanomaterials and reaction engineering. They are applying the findings of this research to advance in their fields. In addition to scientific articles and conference presentations, the PI and the recruited postdoctoral researcher have led seminars at different universities (eg Seoul National Univeristy, Surrey University, Yonsei Univeristy, ) on the performed research, which were attended by postgraduate students and academics. Two centres for doctoral training, one in Sustainable Chemical Technologies at the University of Bath and the other in Catalysis at the Universities of Bath, Bristol and Cardiff, are also being used as platforms for the dissemination and expansion of this research programme, by engaging with PhD students, other academic groups and industry. PhD students in Eslava's group have benefited from the solar simulator bought with this grant to advance their research. In future, this will influence the development of industry and society.
Sectors Chemicals,Energy,Environment,Manufacturing, including Industrial Biotechology,Other

URL https://researchportal.bath.ac.uk/en/persons/salvador-eslava-fernandez
 
Description Bright Ideas, Engineering for a Prosperous Nation
Amount £253,025 (GBP)
Funding ID EP/R035407/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 04/2018 
End 03/2020
 
Description Multiscale Tuning of Interfaces and Surfaces for Energy (MISE) - Flexible Funding Call
Amount £40,594 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 06/2018 
End 12/2018
 
Title Data set for: Mo-doped TiO2 photoanodes using [Ti4Mo2O8(OEt)10]2 bimetallic oxo cages as a single source precursor 
Description The data provided in this data set includes all the raw data collected during the characterization of Mo:TiO2 films: raw data of X-Ray photoelectron spectroscopy (XPS), Electrochemically active surface area (ECSA), X-Ray Diffraction, Raman spectroscopy, Electron Paramagnetic Resonance (EPR), UV-Vis spectroscopy, Photocurrent-Potential curves (J-V), Photocurrent-Time (J-t), Nyquist plots, IPCE (Incident photon-to-current efficiency) and Faradaic efficiency. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Title Data supporting: "Microwave-assisted deep eutectic-solvothermal preparation of iron oxide nanoparticles for photoelectrochemical solar water splitting" 
Description This dataset contains freely-available raw data in support of the named article (10.1039/C7TA02078C), including data from powder X-Ray diffraction, magnetometry measurements, Raman spectroscopy, wide-angle X-Ray scattering performed at the I22 beamline of Diamond Light Source, and photoelectrochemical measurements. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
 
Title Dataset for "Nanostructured WO3 photoanodes for efficient water splitting via anodisation in citric acid" 
Description Research data files for paper "Nanostructured WO3 photoanodes for efficient water splitting via anodisation in citric acid". The data characterise the anodisation of tungsten using citric acid, and were collected from LSV (linear sweep voltammetry), SEM (scanning electron microscopy), IPCE (incident photon-to-current efficiency) measurements, XRD (X-ray diffraction), and UV-VIS (ultraviolet-visible spectroscopy). 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
 
Title Dataset for 'Exploring effects of intermittent light upon visible light promoted water oxidations' 
Description Visible light promoted photocatalytic water oxidations for potential solar fuel production have been studied widely, with many reports on optimization of reagent components. Here we report an exploration on the effects upon ongoing reactions of daylight equivalent light intensity illumination with regulated short dark periods of a few seconds duration as compared to standard continuous illumination. In addition raw XRD data of metal oxide catalysts used, an additional image of reaction flask and a movie file that shows a reaction flask under under cycling RGB LED illumination is given here. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Description Collaboration with Prof. Jong Hak Kim, Yonsei University 
Organisation Yonsei University
Country Korea, Republic of 
Sector Academic/University 
PI Contribution A PhD student from Prof. JH Kim came to my group to do research for 4 months on nanostructured hematite photoanodes. We are finalising a paper on this collaboration
Collaborator Contribution They funded the travel and maintenance of the student Minsu Park to come to my group to work on the project.
Impact We are finalising a research article.
Start Year 2017
 
Description Melanie Colet Lagrille 
Organisation University of Chile
Country Chile 
Sector Academic/University 
PI Contribution We have started a collaboration to develop the topic of this grant. I will host a PhD student from the group of Prof Colet for four months in my group. I cover consumables, access charges and supervision.
Collaborator Contribution Prof Melanie Colet got awarded some funding to send me a PhD student 4 months to my group and to come herself to my group for one month. The funding will also cover my visit to Chile for one week in 2018 and again in 2019. The funding just covers maintenance and flights.
Impact The student has just started a few days ago and my visit to Chile will be in two weeks.
Start Year 2018
 
Description 2nd UK-Korea Focal Point Program - Clean Energy 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact 2nd UK-Korea Focal Point Program - Clean Energy. Work of academics at Yonsei University, University of Edinburgh and University of Bath (my group) was presented. Questions and discussion sparked.
Year(s) Of Engagement Activity 2018
 
Description BK21+ invited talk on "Nanostructuring metal oxides for heterogeneous catalysis and solar water splitting": Brain Korea 21 Program for Leading Universities & Students 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Invited talk at Seoul National University as a BK21+ seminar speaker. Hosted by Prof. Ho Won Jang in the Department of Materials Science and Engineering. We agreed to collaborate in the future in photocatalysis.
Year(s) Of Engagement Activity 2018
 
Description E-MRS 2018 Fall Meeting in Warsaw, Poland 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I presented a poster and an oral talk at the E-MRS showing research outcomes of this proposal. The presentations sparked questions and discussion afterwards. I am still in contact with some of the people that showed interest, for example a student that wanted to test the photoactivity of MoO3. I was also invited to chair a session in the programme
Year(s) Of Engagement Activity 2018
URL http://www.mrs.org/fall2018
 
Description E-MRS Fall Meeting in Warsaw, Poland 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact My presentation in the E-MRS showing research outcomes of this proposal sparked questions and discussion afterwards. I am still in contact with some of the people that showed interest, eg. Prof Davide Barreca, to assess possibilities to submit application to ERC calls. During this conference, I was also invited to go to Seoul National University to give a seminar
Year(s) Of Engagement Activity 2017
 
Description MRS Fall 2017 Conference 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact My research was presented with the title "Nanostructuring metal oxide photocatalysts and photoelectrodes for solar water splitting". My participation sparked many questions and discussion, which were used to advance the community reasearch.
Year(s) Of Engagement Activity 2017
URL http://www.mrs.org/fall2017
 
Description Presentation in the Pint of Science Festival 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Presentation in the Pint of Science Festival titled "Water-fuelled cars? Really?"
Year(s) Of Engagement Activity 2017
 
Description Visit of UK academics to Korea Institute of Energy Research: KIER-Bath-Edinburgh workshop 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I visited the Institute to see their facilities and research and present the work we are doing, which sparked questions and discussion.
Year(s) Of Engagement Activity 2018