Photo-active Materials

Professor Macphee is currently involved in the following research projects:

Photocatalysis and photocatalytic cements

The use of photocatalysts in construction is one of the most sustainable technologies for atmospheric depollution. Globally, concrete structures are ubiquitous in the built environment. Their surfaces are exposed to solar radiation at varying intensities, dependent on latitude, season, time of day, angle of exposure and local weather conditions and they represent significant surface areas which, particularly in urban settings, are typically exposed to the highest levels of air pollution. Our interests range from the fundamental processes activated on an illuminated semiconductor photocatalyst, through the role of the photocatalyst surface on performance, to the influence of cement chemistry on these processes and the role of the catalyst support on catalyst performance.

Our research has received support from various funding agencies. Project Light2CAT, funded under the EU FP7 Framework, led to the development of a visible light TiO2-based photocatalyst with a high degree of selectivity for nitrate during the photocatalytic oxidation of atmospheric NOx gases, and joint EPSRC-NSFC funding enabled collaboration with researchers at Wuhan University of Technology aimed at optimising catalyst supports for construction applications. Collaboration with researchers at the Universidade Federal da Paraíba, funded by CAPES, has focussed on the photocatalytic performance of supported perovskite photocatalysts for wastewater applications.

Selected Publications

  • “Photocatalytic Concretes – The interface between photocatalysis and cement chemistry”, Macphee, D.E. and Folli, A., Cement and Concrete Research, 85, 48-54, (2016), 10.1016/j.cemconres.2016.03.007.
  • “Different Roles of Water in Photocatalytic DeNOx Mechanisms on TiO2: Basis for Engineering Nitrate Selectivity?”, Yang, L., Hakki, A., Wang, F. and Macphee, D.E.,  ACS Appl. Mater. Interfaces, 9, 20, 17034-41, (2017), DOI: 10.1021/acsami.7b01989.
  • “Rationalising photo-electron storage and multi-electron transfer events for improved selectivity in semiconductor photocatalysis”, Folli, A., Bloh, J.Z., Armstrong, K., Richards, E., Murphy, D.M., Lu, L., Kiely, C.J., Smith, R.I., Mclaughlin, A.C. and Macphee, D.E., ACS Catalysis, 8, (8), 6927-38, (2018).
  • “Photocatalytic Concrete for NOx Abatement: Supported TiO2 efficiencies and impacts”, Yang, Lu, Hakki, A., Zheng, L., Jones, R., Wang, F. and Macphee, D.E., Cement and Concrete Research, 116,57-64, (2019), doi:10.1016/j.cemconres.2018.11.002
  • “Supporting the Photocatalysts on Commercial oxide: An Effective Way to Enhance the Photocatalytic Activity of SrSnO3”, Castro Honorio, L.M., Menezes de Oliveira, A.L., da Silva Filho, E.C., Osajima, J.A., Hakki, A., Macphee, D.E., and Garcia, Dos Santos, I.M., Applied Surface Science, 528, 146991, (2020)

Photo-responsive materials for fuel cell and related applications

The commercial uptake of low temperature fuel cells has been limited by the durability of the membrane electrode assembly (MEA). Amongst the most common of the MEA failure modes is the poisoning of the platinum anode electrocatalyst by adsorbed carbon monoxide (CO); CO may enter the fuel cell as an impurity in the fuel (i.e. in hydrogen derived from the reformation of hydrocarbons), or if in a direct methanol fuel cell (DMFC), from fuel oxidation.  CO adsorption can rapidly degrade anode performance at concentrations of only a few parts per million in the fuel. Fuel purity therefore adds cost to the fuel cell’s cost of ownership, through fuel and component replacement costs as well as in the fuel cell down time. Our research in this field grew from our studies on tungsten oxide photocatalysis for water purification and a recognition that the expected drop in a DMFC test cell electrode performance was significantly reduced when using tungsten oxide as a co-catalyst under illumination. Development of this theme has led to several patents and the formation of Enocell Ltd, a university spin out company formed in 2011.

Enocell Ltd aims to become a leading supplier of PEM and DMFC fuel cell modules for stationery devices and alternative power generators for distributed generation and/or stand-by applications. The key proposition is to maximise cell performance ‘in service’, minimise the cost of usable fuel and thus provide greater fuel efficiency and longer service life. The company has an international network of development partners, including fuel cell stack and optical component developers and distributors which support the development and testing of Enocell’s core ‘catalyst illumination’ technology. In parallel, Enocell is developing a range of direct methanol fuel cell (DMFC) systems and prototypes will be available for customer demonstrations in Q3 2020. It is the overall expectation that successful penetration of the PEM and DMFC markets will present the platform on which to subsequently launch Enocell’s innovative illumination technology.

Selected Publications

  • “A visible light driven photoelectrocatalytic fuel cell for clean-up of contaminated water supplies”, Macphee, DE, Wells, RPK, Kruth, A, Todd, M., Elmorsi, T., Smith, C., Pokrajac, D., Strachan, N, Mwinyhija, M, Scott-Emuakpor, E, Nissen, S and Killham, K, Desalination, 248, 132-7, (2009).
  • “A Tungsten Oxide-Based Photoelectrocatalyst for Degradation of Environmental Contaminants”, Macphee, DE, Rosenberg, D, Skellern, MG, Wells, RPK, Duffy JA and Killham K., Journal of Solid State Electrochemistry, 15, (1), 99-103, (2011).
  • “Remediation of 2,4-dichlorophenol contaminated water by visible light-enhanced WO3 Photoelectrocatalysis”, Scott-Emuakpor, EO A Kruth, MJ Todd, A Raab, GI Paton and DE Macphee, Applied Catalysis B: Environmental, 123–124, 433– 439, (2012).
  • “Photocatalytic Reactor”, Macphee, D.E., International Publication Number: WO2004079847 A
  • "The Role of Tungsten Oxide in the Enhancement of Carbon Monoxide Tolerance of Platinum-Based Hydrogen Oxidation Catalysis", Stewart, D., Scott, K., Wain, A., Rosser, T., Brightman, E., Macphee, D., Mamlouk, M., ACS Appl. Mater. Interfaces, (2020), accepted July, 2020.