Introduction

Photo-electrochemical production of hydrogen from water using solar energy and suitable energy conversion systems offers a potential route to a sustainable, carbon-free energy vector. The principal considerations in the design of such systems are materials and reactor structure. Our research is focused on these micro- and macro- aspects in parallel and our goal is to build a prototype device that can successfully demonstrate the spontaneous splitting of water into hydrogen and oxygen upon illumination by solar photons. 

Project aims 

The project aims to model, design, fabricate, characterise, and optimise innovative, low-cost, reactors with stable photo-electrodes for hydrogen production from water, driven by solar energy.

The progress to date is summarised schematically below. We successfully employed tinIV-doped hematite photo-anodes, coupled to a platinised titanium cathode in a system for assisted solar water splitting. Presently our work is focused on coupling the hematite photo-anodes with photo-cathodes for spontaneous solar water splitting in a novel photo-electrochemical demonstration reactor.  

Phase 1 Solar HydrogenPhase 2 Solar Hydrogen from H2OPhase 3 Solar Hydrogen from H2O

Photo-electrochemical reactor

The principal considerations in the design of a photo-electrochemical reactor are:

  • Optimisation of the mechanism for the illumination of both photo-electrodes;
  • Minimisation of ohmic losses between the photo-electrodes, as well as current density distributions across the photo-electrode surfaces;
  • Efficient separation of the gaseous products of the water splitting process, minimising crossover;
  • Effective capture of hydrogen, enabling accurate quantification of the solar to hydrogen conversion efficiency.

Reaction and reactor modelling

Finite element numerical models have been developed of both semiconductor | solution interfaces and of complete reactors to understand:

  • The factors controlling kinetics of Fe2O3 photo-anodes, leading to enhancement of photocurrent densities, quantum yields and energy conversion efficiencies;
  • Spatial distributions of electrical potentials, (photo-) current densities and local dissolved hydrogen and oxygen concentrations;
  • Distributions of local fluid velocities in the reactor and their effects on local reactant and product concentrations, to enable improved reactor design and to relax scale-up limitations.

 

Selected Talks

  1. Talk entitled ‘Photo-electrochemical reactors for hydrogen production’, at the International Discussion Meeting “Solar Fuels: Moving from Materials to Devices”, The Royal Society, London, UK, 7-8 July 2015, F. Bedoya Lora, A. Hankin, G.H. Kelsall and C.K. Ong.
  2. Webinar on ‘H2 production using solar energy’, hosted by the Knowledge Transfer Network, 20 Jan 2015, A. Hankin and G.H. Kelsall. (Note: the recording begins at 0:28 and there are two interruptions to the recording at 01:53-02:52 and 39:21-45:09).‌ Download Webinar
  3. Talk entitled ‘Photo-electrochemical energy conversion and storage’ at the Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014), 7-11 Dec 2014, G. Kelsall and A. Hankin.
  4. Talk entitled 'Comparing 'photo-electrochemical' and 'electrochemical-powered-by-PV' systems for solar H2O splitting' at the Imperial Solar Fuels Symposium 2014, Imperial College London, 10 Dec 2014, A. Hankin and G. H. Kelsall. Download
  5. Talk entitled ‘Photo-electrochemical production of hydrogen using solar energy’ at the 10th European Symposium on Electrochemical Engineering (10th ESEE), 28 Sep – 2 Oct 2014, Sardinia, Italy, A. Hankin, G. Kelsall, C. K. Ong and F. Petter. Download
  6. Talk entitled ‘(Photo-)electrochemical energy conversion and storage’ at the  65th Annual Meeting of the International Society of Electrochemistry (ISE 2014), 31 Aug - 5 Sep 2014  Lausanne, Switzerland, A. Hankin, G. Kelsall and L. Kleiminger.
  7. Talk on the 'Incorporation of CIGS cells into photo-electrochemical reactors' at IMEM-CNR, Parma, Italy, 17 Jul 2014, A. Hankin. Download
  8. Talk entitled 'Towards reactor design...' at the 'Do we need a global project on artificial photosynthesis (solar to fuels and chemicals)?' meeting of The Royal Society, Kavli Royal Society Centre, 8-10 Jul 2014, A. Hankin. Read essay submitted to the conference proceedings. Download
  9. Talk entitled 'Photo-electrochemical production of H2 using α-Fe2O3 photo-anodes' at Electrochem 2013, University of Southampton, 1-3 Sep 2013, A. Hankin, C. K. Ong, F. Petter and G. H. Kelsall.
  10. Talk entitled 'Evaluation of hematite as a photo-anode' at the Imperial Solar Fuels Symposium 2013, Imperial College London, 13 Mar 2014, A. Hankin. Download
  11. Talk entitled 'Photo-electrochemical production of H2 using a α-Fe2O3 photo-anodes' at the UK-Korea H2 Workshop, University of Birmingham, A. Hankin, C. K. Ong, S. Dennison, K. Hellgardt and G. H. Kelsall.  

Selected Publications

  1. J. J. H. Videira, K. W. J. Barnham, A. Hankin, J. P. Connolly, M. Leak, J. Johnson, G. H. Kelsall, K. Kennedy, J. S. Roberts, A. J. Cowan and A. J. Chatten, Introducing novel light management to design a hybrid high concentration photovoltaic/water splitting system (2015) IEE PVSC 42 IProceedings (In Press)
  2. A. Hankin, J.C. Alexander and G.H. Kelsall,  Constraints to the flat band potential of hematite photo-electrodes (2014) Phys. Chem. Chem. Phys., 16, pp. 16176-16186, DOI: 10.1039/C4CP00096J
  3. C. K. Ong, S. Dennison, S. Fearn, K. Hellgardt and G. H. Kelsall Behaviour of titanium-based Fe2O3 photo-anodes in photo-electrochemical reactors for water splitting (2014), Electrochim. Acta, 125, pp. 266-274, DOI: 10.1016/j.electacta.2014.01.086
  4. C. Carver, Z. Ulissi, C. K. Ong, S. Dennison, G. H. Kelsall and K. Hellgardt, Modelling and development of photoelectrochemical reactor for H2 production (2012), Int. J. Hyd. Eng., 37, pp. 2911–2923, DOI: 10.1016/j.ijhydene.2011.07.012
  5. C. K. Ong, S. Dennison, K. Hellgardt and G. H. Kelsall, Evaluation and modeling of a photo-electrochemical reactor for hydrogen production operating under high photon flux (2011), ECS Trans., 35, pp. 11-19, DOI: 10.1149/1.3646098
  6. C. Carver, Z. Ulissi, C. K. Ong, S. Dennison, K. Hellgardt and G. H. Kelsall, Modeling and evaluation of a photoelectrochemical reactor for H2 production (2010), ECS Trans., 28, pp. 103-117, DOI: 10.1149/1.3501099  

Contact

For further information please contact Professor Geoff H. Kelsall g.kelsall@imperial.ac.uk or visit the Solar Fuels Network website for educational material and up to date list of upcoming symposia / conferences.