Developing photoelectrochemical water splitting devices - from understanding charge carrier behaviour to testing prototypes in the field
Brian Tam,1 George Creasey,2 Anna Hankin,2 Andreas Kafizas1,3
1 Department of Chemistry, Imperial College London, United Kingdom
2 Department of Chemical Engineering, Imperial College London, United Kingdom
3 The London Centre for Nanotechnology, Imperial College London, United Kingdom
Abstract
Current H2 demands are vast, with the industry valued in excess of $100 billion. Today, most H2 is produced using non-renewable methods that account for ~3% of total CO2 emissions.1 Various renewable methods for producing H2 are being developed, with solar-driven photoelectrochemical (PEC) water splitting a promising avenue in terms of efficiency and cost.2 State-of-the-art PEC systems have achieved solar-to-hydrogen (STH) efficiencies above 8%;3 nearing benchmark efficiencies for commercial viability.4 However, for this technology to reach commercial maturity, prototypes need to be demonstrated on a scale commensurate to their intended application.5 In this talk, I will present the ongoing work in my group on the development of scalable synthetic routes to high performance photoanodes (Figure 1(a)), using chemical vapor deposition (Figure 1(b)). I will also show how studies of the charge carrier behavior in these PEC systems can reveal the kinetic processes that control activity, providing unique insight on the rational design of more efficient systems. And lastly, I will present our ongoing work on the development and field trial testing of PEC water splitting prototypes, approaching the ~100 cm2 scale (Figure 1(c)).
Figure 1: (a) Incident photon-to-current efficiencies seen at 1.23 V vs RHE for an optimised BiVO4-based photoanode in a neutral buffered electrolyte, (b) the CVD reactor used to produce moderate scale photoanodes (~50 cm2 in size) and (c) the PEC water splitting prototype in action.
References
1. IEA, Hydrogen - Fuels & Technologies, 2020.
2. B. Moss, O. Babacan, A. Kafizas and A. Hankin, Adv Energy Mater, 2021, 2003286, 1–43.
3. Y. Pihosh, I. Turkevych, K. Mawatari, J. Uemura, Y. Kazoe, S. Kosar, K. Makita, T. Sugaya, T. Matsui, D. Fujita, M. Tosa, M. Kondo and T. Kitamori, Scientific Reports, 2015, 5, 11141.
4. L. Hammarström and J. Durrant, Mission Innovation Challenge ‘Converting Sunlight’ , 2017.
5. J. H. Kim, D. Hansora, P. Sharma, J. W. Jang and J. S. Lee, Chem Soc Rev, 2019, 48, 1908–1971.
Biography
Dr. Andreas Kafizas is a Senior Lecturer in the Department of Chemistry at Imperial College London (ICL). His research is focused on developing sustainable synthetic routes to photocatalytic coatings for a range of practical applications, including renewable fuels production (e.g. hydrogen fuel from water and carbon-based fuels from carbon dioxide), air remediation (e.g. nitrogen oxides removal) and water remediation (e.g. arsenic removal). To date, Andreas has published over 100 peer-reviewed papers and has written 6 book chapters (>7,100 citations, h-index = 52).
Andreas completed his MSci in Chemistry in 2007, and PhD in Chemistry in 2011 at University College London. His PhD was focussed on the development of photocatalytic materials synthesised by chemical vapour deposition, and he was awarded the Ramsay Medal for best graduating doctor. In 2012, he was awarded the Ramsay Fellowship, where studied the charge carrier behaviour of photocatalytic materials for solar fuels at ICL. In 2016, he was awarded a Junior Research Fellowship at ICL to develop heterojunction photoelectrodes for solar water splitting. In 2018, he was awarded a Lectureship at ICL, and now leads the Solar Coatings Group, is the theme lead in Sustainable Power and Renewable Fuels at the Energy Futures Lab, and is a board member at the London Centre for Nanotechnology.