I was appointed as the Chemistry Engineering Steel Bridge Professor at Swansea University in March 2017. My research interests are industry facing and relate to advanced materials and related manufacturing processes. Hence, we use fundamental chemical understanding of molecules and interfaces to understand and solve large-scale materials engineering and manufacturing issues.

Currently, we work in three main areas:

  1. Advanced devices such as photovoltaics (solar cells)
  2. Steel manufacturing and value-added products
  3. Water treatment

Publications

  1. & Dissolved organic carbon and trihalomethane precursor removal at a UK upland water treatment works. Science of The Total Environment 468-469, 228-239.
  2. & Study of the tribological properties and ageing of alkyphosphonic acid films on galvanized steel. Tribology International
  3. & Digital imaging to simultaneously study device lifetimes of multiple dye-sensitized solar cells. Sustainable Energy Fuels 1(2), 362-370.
  4. & Studies of inherent lubricity coatings for low surface roughness galvanised steel for automotive applications. Lubrication Science 29(5), 317-333.
  5. & Convenient synthesis of EDOT-based dyes by CH-activation and their application as dyes in dye-sensitized solar cells. J. Mater. Chem. A 4(40), 15655-15661.

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Supervision

  • Understanding the fundamentals of Cr-free pre-treatments (current)

    Student name:
    EngD
    Other supervisor: Dr Eifion Jewell
  • Advanced Wastewater Treatment focused on the minimisation of oil leaks and separation of oil/contaminants from wastewater. (current)

    Student name:
    EngD
    Other supervisor: Dr Chedly Tizaoui
  • New Generation Foam to Revolutionise the Building Industry (current)

    Student name:
    EngD
    Other supervisor: Dr Ian Mabbett
  • Surface chemistry of kaolin clay minerals and the prediction of soil adsorption properties (current)

    Student name:
    PhD
    Other supervisor: Prof David Worsley
  • Studies of Dye-Titania Interactions in Dye-Sensitized Solar Cells«br /» (current)

    Student name:
    PhD
    Other supervisor: Prof David Worsley
  • Alternative reductants in iron making with a focus on the novel material, Subcoal (current)

    Student name:
    PhD
    Other supervisor: Prof David Worsley

Advanced devices such as photovoltaics (solar cells)

We are currently working on two EPSRC-funded projects; one on perovskite solar cells (PSC) and the other on dye-sensitized solar cells (DSSC)

Self-assembling Perovskite Solar Cells

I am PI on a £2.5M EPSRC grant (EP/M015254/1) working with Prof Henry Snaith FRS (Physics, Oxford) and Prof Dave Worsley and Dr Trystan Watson (Engineering, Swansea) to study self-assembly approaches towards roll-to-roll (R2R) manufacturing of perovskite solar cells on flexible substrates. In this context, self-assembly can be defined as a process by which perovskite device sub-components adopt a desired device arrangement without external input.

Our group is designing and synthesising device sub-components to enable self-assembly and then to develop in situ metrology (e.g. spectroscopy, visualisation) to monitor the self-assembly and overall manufacturing progress. To date, we have identified limitations of toxic manufacturing solvents1,2and developed solvent-free self-assembly of perovskite onto metal oxide scaffolds leading to the development of inks based on benign solvents3. The resultant perovskite films also exhibit enhanced stability to humidity and air exposure. We are currently extending the self-assembly approach to Pb-free perovskites and to other device sub-components (e.g. substrates, charge carrying layers).

1        A.E. Williams, P.J. Holliman, M.J. Carnie, M.L. Davies, D.A. Worsley, T.M. Watson, J. Mater. Chem. A, 2014, 2, 19338.

2        P.J. Holliman, A. Connell, E.W. Jones, S. Ghosh, L. Furnell, R.J. Hobbs, Materials Research Innovations, 2015, 19, 508-511.

3        E.W. Jones, P.J. Holliman, A. Connell, M.L. Davies, J. Baker, R.J. Hobbs, S. Ghosh, L. Furnell, R. Anthony, C. Pleydell-Pearce, Chem. Commun., 2016, 52, 4301-4304.

Self-assembling Dye-sensitized Solar Cells (DSSC)

The major challenges for scaling DSSC technology for wider product use are improving device efficiency, manufacturing and lifetime. Improving efficiency requires dyes which extend spectral response to λ > 650nm to increase light harvesting. To achieve this, we have pioneered rapid co-sensitization of multiple dyes1-3. This approach is preferable to using panchromatic dyes where Voc is limited by smaller HOMO-LUMO energy gaps which lower device Fermi levels. However, we have shown that controlling the dye-TiO2 interface is more complex for multiple dyes4. In addition, DSC lifetimes are limited by volatile and corrosive liquid electrolytes, which limit flexible substrate choice to more expensive, inert and non-permeable materials. Liquid electrolytes also complicate device manufacturing and sealing. To date, changing to solid state DSC (ss-DSC) devices has been limited by deficient pore filling by hole transport materials (HTMs) which impairs dye-electrolyte interfaces. With EPSRC support (EP/P030068/1) and working with partners at Glasgow (Prof Graeme Cooke), STFC-Daresbury (Drs Dawn Geatches and Sebastien Metz) and Swansea (Prof Dave Worsley, Drs Cecile Charbonneau and Matt Carnie), we are designing molecules which can self-assemble at the dye-TiO2 and dye-electrolyte interfaces with the aim of achieving rapid, one-step and scalable manufacturing of solid state-DSSC devices

  1. P.J. Holliman, M.L. Davies, A. Connell, B. Vaca Velasco, T.M. Watson, Chem. Comm., 2010, 46, 7256.
  2. P.J. Holliman, M. Mohsen, A. Connell, M.L. Davies, K. Al-Salihi, M.B. Pitak, G.J. Tizzard, S.J. Coles, R.W. Harrington, W. Clegg, C. Serpa, O.H. Fontes, C. Charbonneau, M.J. Carnie, J. Mater. Chem., 2012, 22, 13318.
  3. A. Connell, P.J. Holliman, M.L. Davies, C.D. Gwenin, S. Weiss, M.B. Pitak, P.N. Horton, S.J. Coles, G. Cooke, J. Mater. Chem. A, 2014, 2, 4055.
  4. P.J. Holliman, K.J. Al-Salihi, A. Connell, M.L. Davies, E.W. Jones, D.A. Worsley, RSC Advances, 2014, 4(5), 2515.

Steel manufacturing and value-added products

Steel is a ubiquitous engineering material used in applications ranging from buildings to vehicles to bridges to pipelines etc. Whist steel can be recycled (e.g. in electric arc furnaces) this uses large amounts of electricity and produces steel containing the trace elements of the incoming scrap metal which limits its future usage.  By comparison, steel making from iron ore takes place in a blast furnace (BF). BF-based steel manufacturing is a complex and energy intensive process where material added from the top joins the “burden” which gradually moves down the BF whilst, at the same time, hot gas and material are added at the base to ensure maximum conversion of Fe2O3 into iron. That is, the maximum atom efficiency of Fe atoms in the process where atom efficiency is the conversion efficiency of a chemical process in terms of all the raw material atoms compared to the atoms in the desired products.

We are extending this concept of atom efficiency to the entire blast furnace process to consider carbon and other raw material inputs as well as other BF by-products. In this context the overall blast furnace (BF) production of iron can be described by the equation [Fe2O3(s) + 3CO(g) = 2Fe(l) + 3 CO2(g)]; i.e. the carbo-thermal reduction of Fe2O3 using C which is typically supplied to the blast furnace as coke. Raw material purity determines blast furnace slag impurities whilst coke quality helps to support the blast furnace burden, is converted to CO to reduce the Fe2O3 and its exothermic combustion provides energy for the carbo-thermal reaction. All of these factors will need to be considered when studying the atom efficiency of other components.

In terms of value added products, we are using scalable, rapid processing techniques to self-assembly active nano-layers onto metal or metal oxide surfaces to control hydrophobicity and to imbue inherent lubricity into different steel grades1. This enables deep drawing and forming processes to be carried out without the need to lubricating oils and emulsions which can be difficult to dispose of.

  1. D. Hill, P.J. Holliman, J. McGettrick, J. Searle, M. Appelman, P. Chatterjee, T.M. Watson, D. Worsley, Lubrication Science, 2017, in press. DOI: 10.1002/ls.1370

Water Treatment

Potable water treatment has been known to be essential for human health since cholera outbreaks in London in the 1800’s. At that time, chlorination was developed into a cost-effective disinfection method which is still widely used today. However, water disinfection using chlorine produces disinfection by-products (DBPs) which result from dissolve organic carbon (DOC) reacting with reactive chlorine species1,2. Modern water treatment works are designed to remove DOC prior to disinfection. However, not all DOC can be removed, which gives rise to DBPs.

            Currently, we are working to address the growing DOC concentrations resulting from climate change which place increasing pressure on water companies to meet current legal limits for DBP concentrations in potable water whilst still providing pathogen-free water to drink. Our approaches are currently focussed on a better understanding of DBP precursors3 and on their removal4.

  1. R. Gough, P.J. Holliman, C. Freeman, Sci. Total Environ., 2014, 468-469, 228
  2. E. Brooks, C. Freeman, R. Gough, P.J. Holliman, Sci. Total Environ., 2015, 537, 203–212.
  3. D.D. Hughes, P.J. Holliman, T. Jones, A.J. Butler, C. Freeman, Natural Science, 2016, 8, 487-498.
  4. R. Gough P.J. Holliman, T.R. Heard, C. Freeman, J. Water Supply: Res. Technol. — AQUA, 2014, 63(8), 650-660.

STEM Outreach Work

We also have interests in publicising STEM (science technology engineering and mathematics) within society. In the past, we have received support from EPSRC for this for the Chemistry Show-Sioe Cemeg outreach activity in North Wales. More recently, we have been designing interactive, practical STEM activities and outreach lectures. So far, we have presented these to:

  • School children in Romania
  • At different year groups at several North Wales schools.
  • To Sixth Form students at STFC-Daresbury