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Personal profile

Biography

Biography

Dr. Fielden completed his MSci in Chemistry at the University of Bristol in 2000, before moving to the University of Glasgow where he graduated with a Ph.D in 2005 under the supervision of Prof. Leroy Cronin. He then spent two years working with Prof. Paul Kögerler at Ames Laboratory (Iowa State University) on the self-assembly and properties of polyoxometalates (POMs) and chiral magnetic materials. In 2007 he took up a postdoctoral position with Dr. Benjamin Coe at the University of Manchester, investigating redox-switchable NLO chromophores, and in 2010 was awarded a Marie Curie International Outgoing Fellowship. This took him back across the Atlantic to the laboratory of Prof. Craig Hill at Emory University, where he worked on POM functionalized photoelectrodes and the excited state properties of transition metal substituted POMs. He joined the UEA as a lecturer in 2012, transferring his Marie Curie reintegration year from Glasgow, and was promoted to Senior Lecturer in 2018.

John is interested in the synthesis and optical and photophysical properties of coordination compounds and clusters, particularly relating to solar energy conversion and non-linear optics. Since joining UEA the main focus of his work has been the study of arylimido-polyoxometalates (a-POMs) as non-linear optical chromophores, and as sensitisers and coadsorbents for the p-type dye-sensitised solar cell, both applications making use of the POM's properties as an electron acceptor. He is also working to develop luminescent sensors for i-motif DNA with Dr Zoë Waller (formerly UEA, now UCL School of Pharmacy). To see a YouTube video about this work, click here.

Click here to go to the Energy Materials Laboratory homepage.

Selected Publications

Ahmed Al-Yasari, Hani El Moll, Ryan Purdy, Keven B. Vincent, Philip Spence, Jean-Pierre Malval and John Fielden
Optical, Third Order Non-Linear Optical and Electrochemical Properties of Dipolar, Centrosymmetric and C2v Organoimido Polyoxometalate Derivatives
Phys. Chem. Chem. Phys. 202153, 11120-11129
DOI:
10.1021/acs.macromol.0c02354

Sarah A. Alshehri, Ahmed Al-Yasari, Frank Marken and John Fielden
Covalently Linked Polyoxometalate-Polypyrrole Hybrids: Electropolymer Materials with Dual-Mode Enhanced Capacitive Energy Storage
Phys. Chem. Chem. Phys. 2021, 23, 11807-11817
DOI:
10.1039/DP0CP06610A

Philip Spence, John Fielden and Zoë A. E. Waller
Beyond Solvent Exclusion: i-Motif Detecting Capability and An Alternative DNA Light-Switching Mechanism in a Ruthenium(II) Polypyridyl Complex
J. Am. Chem. Soc. 2020, 14213856-13866. 
DOI:
 10.1021/jacs0c04789. Click here to check out Zoë's YouTube video.

Simon N. Child, Radoslav Raychev, Nathan Moss, Benjamin Howchen, Peter N. Horton, Christopher C. Prior, Vasily S. Oganesyan and John Fielden.
Cobalt-based molecular electrocatalysis of nitrile reduction: evolving sustainability beyond hydrogen.
Dalton. Trans. 2019, 48, 9576-9580. Contribution to sustainability theme of d-block chemistry special issue and highlighted by ChemistryViews.
DOI:
 10.1039/c9dt00773c

Ahmed Al-Yasari, Philip Spence, Hani El Moll, Nick Van Steerteghem, Peter N. Horton, Bruce S. Brunschwig, Koen Clays and John Fielden.
Fine-tuning Polyoxometalate Non-Linear Optical Chromophores: A Molecular Electronic "Goldilocks" Effect.
Dalton. Trans. 2018, 4710415-10419. Inside front cover of New Talent Europe special issue.
DOI:
 10.1039/c8dt01491d

Ahmed Al-Yasari, Nick Van Steerteghem, Hayleigh Kearns, Hani El Moll, Karen Faulds, Joseph A. Wright, Bruce S. Brunschwig, Koen Clays and John Fielden.
Organoimido-Polyoxometalate Non-Linear Optical Chromophores: A Structural, Spectroscopic and Computational Study
Inorg. Chem. 2017, 56, 10181-10194.
DOI:
 10.1021/acs.inorgchem.7b00708

Hani El Moll, Fiona A. Black, Christopher J. Wood, Ahmed Al-Yasari, Anil Reddy Marri, Igor V. Sazanovich, Elizabeth A. Gibson and John Fielden. 
Increasing p-type dye sensitised solar cell photovoltages using polyoxometalates
Phys. Chem. Chem. Phys. 2017, 19, 18831-18835.
DOI:
 10.1039/C7CP01558E

John Fielden, Jordan M. Sumliner, Nannan Han, Yurii Gueletii, Xu Xiang, Djamaladdin G. Musaev, Tianquan Lian, and Craig L. Hill.
Water Splitting with Polyoxometalate-Treated Photoanodes: Enhancing Performance through Sensitizer Design
Chem. Sci. 20156, 5531-5543.
DOI:
10.1039/C5SC01439E

 

 

 

Career

  • 2018 - Senior Lecturer (now Associate Professor) in Energy Materials, UEA School of Chemistry 
  • 2012 – Lecturer in Energy Materials, UEA School of Chemistry (confirmed spring 2016)
  • 2010 – 2013 Marie Curie International Outgoing Fellow, Emory University (Atlanta, USA) and UEA
  • 2007 – 2010 Post-Doctoral Research Associate, University of Manchester
  • 2005 – 2006 Post-Doctoral Research Associate, Ames Laboratory (US Department of Energy)
  • 2001 – 2004 Ph.D in Inorganic Chemistry, University of Glasgow
  • 1996 – 2000 MSci in Chemistry, University of Bristol

Key Research Interests

The Fielden group is currently working in the following areas:

  • Polyoxometalate-based non-linear optical chromophores and electropolymers. We have recently obtained a series of donor-acceptor chromophores based on polyoxometalates, including systems based on electropolymerizable pyrrole units.  The resulting materials obtain unusually high activity from moderate donor groups and short pi-systems, due to extension of charge transfer onto the POM. We are now working to develop ways of including these materials in films with bulk NLO activity and switchable responses.
  • New catalysts: We are using small, heteroleptic tripodal ligands as a platform to build catalysts for small molecule activation.  The ligands can coordinate a transition metal in a bidentate or tetradentate coordination pocket, while providing a pendant group for introduction of proton or electron relays.  These will allow controlled study of secondary coordination sphere effects. 
  • POM-derivatives as photosensitizers: We are investigating the use of POMs as electron acceptor units in push-pull chromophores.  These are designed to improve the efficiency of p-type dye-sensitized solar cells by retarding recombination of photo-excited electrons to NiO, one of the major sources of inefficiencies in these systems.  
  • New p-type semiconductor nanomaterials: In this project, supported by EU Marie Curie fellowship NanoCuI to Dr. Anil Reddy Marri, we are developing nanoporous copper iodide substrates as a replacement of the NiO p-type semiconductor in the p-type dye-sensitized solar cell (p-DSSC, collaboration with Dr. Andrew Mayes, UEA and Dr Elizabeth Gibson, Newcastle). p-DSSCs, in combination with conventional n-type DSSCs, could be used to make tandem DSSCs with better spectral coverage (light absorption at both electrodes) and photovoltage. However, at present p-DSSCs do not perform well enough to realise this promise, because the conductivity of the NiO substrate is poor. Gamma-CuI has an intrinsically much higher conductivity than NiO, so could produce much better devices, but the high surface area nanoporous electrodes needed for efficient dye sensitization do not yet exist. We are using chemical and electrochemical deposition methods to develop them.

External Activities

  • School Visits - Wollaston School, 2021; The Deepings School, March 2017; Trent College, February 2016
  • Invited Research Talks: RWTH Aachen University (2019), University of Sussex (2018), University of Glasgow (2017), FMOCS-PoCheMon (2016), University of Newcastle (2016), University of Southampton (2016); Emory University (2015), University of Central Lancashire (2015)
  • Outreach - Norwich Science Cafe 2013 - Talk on Artificial Photosynthesis
  • Outreach - Photon Science Institute/Manchester Museum of Science and Industry 2010 - Meet the Photon Scientist

Administrative Posts

Module Organiser: Year 2 Inorganic Chemistry (CHE-5301B)

Head of Second Year Chemistry

Chemistry Representative: Science Faculty Analytical Facilities User Group

 

Research Group or Lab Membership

Current Group Membership: Claire Jones (Leverhulme Funded PDRA), Katie Littler (PhD student).  

Fielden Group Autumn 2018

 

 

Fielden and Wright Groups, August 2017

 The Fielden and Wright Groups, August 2017

 From left to right: Farhana Haque (PhD, JAW), Trevor Simmons (PDRA, JAW), John Fielden, Joseph Wright, Anil Reddy Marri (Marie Sklodowska Curie Fellow, JF, 2015-17)

The Fielden Group, February 2015

From left to right: Simon Child, John Fielden, Natalia Sanchez Moreno, David Miko, Phil Spence, Hani El-Moll, Ahmed Al-Yasari

From left to right: Simon Child, John Fielden, Natalia Sanchez Moreno, David Miko, Phil Spence, Hani El-Moll, Ahmed Al-Yasari

And among the Ziggurats...

Fielden group outside the UEA Ziggurat buildings

Fielden group outside the UEA Ziggurat buildings

 

 

Expertise related to UN Sustainable Development Goals

In 2015, UN member states agreed to 17 global Sustainable Development Goals (SDGs) to end poverty, protect the planet and ensure prosperity for all. This person’s work contributes towards the following SDG(s):

  • SDG 7 - Affordable and Clean Energy

Keywords

  • QD Chemistry
  • Inorganic chemistry
  • Photochemistry
  • Coordination chemistry
  • Non-linear optics
  • Coordination clusters
  • Polyoxometalates
  • Artificial photosynthesis

Network

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