Welcome to the Institute of Solar Fuels

At the Institute for Solar Fuels we develop new materials and devices for the production of chemical fuels from cheap and abundant resources, such as water and CO2, using sunlight. Our current efforts are focused on photo-electrochemical water splitting. Towards this end, we develop deposition processes and synthesis routes for thin film and nanostructured semiconductors and catalysts, and we investigate the fundamental processes of charge generation, separation, and transfer in the bulk and at the interfaces of these materials. Of particular interest is the role of defects, which we aim to control by developing thermal treatments, passivation layers, and doping strategies. Our experimental toolbox includes a range of thin film deposition techniques, electrochemistry and photo-electrochemistry, time-resolved spectroscopy on fs – s time scales, and synchrotron-based methods under operando conditions.

News and Recent Publications

Advances in Photoelectrochemical Water Splitting

Advances in Photoel. Water Splitting

Edited by scientists from EPFL, NREL, and HZB, this book provides an overview of recent advances in photoelectrochemical water splitting. It starts by outlining the challenges in the field, followed by theoretical approaches toward materials screening and design. This is followed by chapters on identification on reaction intermediates, charge transfer, solution-processed photoelectrodes, nanoparticulate systems, and the use of bipolar membranes in water splitting devices. The final part is on the modeling of PEC devices and a techno-economic analysis of water splitting at various scales. The chapters are written by internationally reknowned experts in this exciting and fast-developing field.

 

 

 

“Advances in Photoelectrochemical Water Splitting – Theory, Experiment and Systems Analysis”, Edited by S.D. Tilley, S. Lany, and R. van de Krol.
RSC Publishing (2018).  ISBN: 978-1-78262-925-2

Pathways to electrochemical solar-hydrogen technologies

In this paper, more than 40 scientists join forces to discuss potential pathways for solar hydrogen technologies. This work is the result of a one-week focused workshop that all authors attended in the summer of 2016 at the Lorentz center in Leiden, the Netherlands. Various technical approaches, societal impact, economic drivers, technical challenges, and research opportunities are outlined, followed by both short- and long-term implementation scenarios.

 

S. Ardo, D. Fernandez Rivas, M. Modestino, V. Schulze Greiving, F.F. Abdi, E. Alarcon Llado, V. Artero, K. Ayers, C. Battaglia, J. Becker, D. Bederak, A. Berger, F. Buda, E. Chinello, B. Dam, V. Di Palma, T. Edvinsson, K. Fujii, H. Gardeniers, H. Geerlings, S. Mohammad, H. Hashemi, S. Haussener, F. Houle, J. Huskens, B.D. James, K. Konrad, A. Kudo, P. Patil Kunturu, D. Lohse, B. Mei, E.L. Miller, G. F. Moore, J. Muller, K.L. Orchard, T.E. Rosser, F. Saadi, J.W. Schüttauf, B. Seger, S.W. Sheehan, W.A. Smith, J. Spurgeon, M. Tang, R. van de Krol, P.C.K. Vesborg, P. Westerik, Pathways to electrochemical solar-hydrogen technologies, Energy Env. Sci., in press (2018)

Review on advances in rational engineering of multinary oxides for water splitting

The group of Prof. Hongqiang Wang at Northwestern Polytechnical University in Xi’an, China, published an extensive review in Nano Energy on multinary metal oxide photoelectrodes and various approaches on how to improve the performance of these materials. We contributed to part of this interesting and comprehensive review.

 

J. Jian, G. Jiang, R. van de Krol, B. Wei, H. Wang, Recent Advances in Rational Engineering of Multinary Semiconductors for Photoelectrochemical Hydrogen Generation, Nano Energy 51, 457-480 (2018)

FeVO4 photoanodes for solar water oxidation

FeVo4 photoanodes

Together with our colleagues from Nanyang Technological University in Singapore, we explored FeVO4 as a potential photoanode material for water splitting. With a bandgap of 2.07 eV this material is a good visible light absorber, but we find that the material suffers from low carrier mobilities. Intriguingly, doping the material with molybdenum enhances both the carrier mobility and lifetime by a factor of 3. Despite this improvement, extensive nanostructuring is likely needed to obtain practical photocurrent densities.

 

Zhang, Y. Ma, D. Friedrich, R. van de Krol, L.H. Wong, F.F. Abdi, Elucidation of the opto-electronic and photoelectrochemical properties of FeVO4 photoanodes for solar water oxidation, J. Mater. Chem. A 6, 548-555 (2018)

Perspectives on the photoelectrochemical storage of solar energy

storage of solar energy

In this paper, we argue that water splitting will be a central challenge for any fossil fuel-free energy infrastructure that relies on liquid or gaseous chemical fuels. We discuss potential advantages of integrated ‘direct’ photoelectrolysis vs. PV-driven electrolysis and outline several key challenges and research needs in the field.

 

 

R. van de Krol and B.A. Parkinson, “Perspectives on the Photoelectrochemical Storage of Solar Energy, MRS Energy Sustain. 4, E13 (2017)

Gradient Doping improves charge separation in CuBi2O4 photocathodes

charge separation CuBi2O4

p-Type CuBi2O4 is a candidate material for photoelectrochemical water splitting. By deliberately introducing a gradient in the Cu vacancy concentration, the charge separation efficiency in sprayed CuBi2O4 photocathodes could be significantly enhanced. This resulted in an AM1.5 photocurrent of 2.5 mA/cm2 in the presence of an electron scavenger, a new record for this material. Together with our colleagues from the University of Zurich, we also developed a CdS/TiO2/Pt protection layer to prevent (photo)corrosion. These protected photocathodes showed a photocurrent density of -1.0 mA/cm2 at 0 V vs. RHE and evolve hydrogen with a Faradaic efficiency of 91%.

 

F. Wang, W. Septina, A. Chemseddine, F.F. Abdi, D. Friedrich, P. Bogdanoff, R. van de Krol, S.D. Tilley, S.P. Berglund, "Gradient self-doped CuBi2O4 with highly improved charge separation efficiency", J. Am. Chem. Soc. 139, 15094 (2017)

Hydrogen treatment extends charge carrier lifetime in metal oxide photoelectrodes

Photoelectrodes based on metal oxides have only shown relatively low efficiency, due to poor carrier transport properties and a large concentration of point defects that may act as performance killers. By treating the material at moderate temperatures (300°C) in a hydrogen atmosphere, the photoactivity can be significantly improved. Together with our collaborators, we showed that hydrogen goes into the BiVO4 lattice, where it passivates defects and increases the carrier lifetime by more than a factor of two.

 

J.W. Jang, D. Friedrich, Ss Müller, M. Lamers, H. Hempel, S. Lardhi, Z. Cao, M. Harb, L. Cavallo, R. Heller, R. Eichberger, R. van de Krol, and F. F. Abdi*, Enhancing Charge Carrier Lifetime in Metal Oxide Photoelectrodes through Mild Hydrogen Treatment”, Adv. Energy Materals, 1701536 (2017)

 

Read press release at HZB website here

Operando study of light-induced reactions at BiVO4 surface

JPCB_highlights

We investigated light-induced modifications of the BiVO4/electrolyte interface. A BiVO4 sample was kept in contact with a phosphate buffer solution while the interface was probed using AP-HAXPES. Measurements were performed at open circuit potential, under dark and light conditions (1 Sun). We find that under illumination bismuth phosphate forms on the BiVO4 surface leading to an increase in negative charge and a re-distribution of the aqueous ions near the interface. The bismuth phosphate layer may act to passivate surface states observed in complementary photoelectrochemical measurements. Finally, we find that such changes are reversible upon returning to dark conditions.

 

M. Favaro,* F. F. Abdi, M. Lamers, E. J. Crumlin, Z. Liu, R. van de Krol, D. E. Starr*, “Light-induced Surface Reactions at the Bismuth Vanadate/Potassium Phosphate Interface”, J. Phys. Chem. B, (accepted, 2017)

High oxygen evolution activities for electrodeposited α-Mn2O3 films

The generation of hydrogen by solar-driven electrochemical water splitting is a possible approach to store renewable energies as a non-fossil fuel in large quantities. To achieve this goal, earth-abundant and highly active catalysts for both half reactions, the hydrogen and the oxygen evolution reaction (OER), have to be identified and developed for a mass market. This kind of catalysts should be applicable in photoelectrochemical water splitting devices, by being deposited as co-catalysts on the surface of suitable photoelectrodes.
Under this aspect, highly porous manganese(III) oxide layers have been developed as OER electrodes showing low over voltages (340mV at 10mA/cm2 current density).

 

M. Kölbach, S. Fiechter, R. van de Krol, P. Bogdanoff, "Evaluation of electrodeposited α-Mn2O3 as a catalyst for the oxygen evolution reaction", Catalysis Today, 290, p. 2-9, (2017)