|B.Sc.||Universidad de Valencia, Spain (2003)|
|M.Sc.||Universidad Autónoma de Madrid, Spain (2006)|
|Ph.D.||Universidad Autónoma de Madrid and Instituto de Catálisis y Petroleoquímica (CSIC), Spain (2009)|
|Forschungsaufenthalte ||University of Oxford, UK (Prof. Fraser Armstrong) (2005) and Texas A&M University, USA (Prof. Marcetta Darensbourg)|
|Postdoc||MPI für Bioanorganische Chemie; heute: MPI CEC (2009-2013)|
|Gruppenleiter||MPI CEC (seit 2013)|
Our group’s research is focused on the electrochemical study of hydrogen cycling catalysts, more specifically hydrogenases and bio-inspired molecular catalysts. Hydrogenases are the most efficient noble-metal-free catalysts for H2 production or oxidation. These enzymes use earth abundant metals in the active site (as Ni or Fe) and work at almost no overpotential under mild conditions.1 Chemists have been studying these enzymes to understand their unique properties and learn how to design bio-inspired catalysts avoiding the use of noble metals. The goal is to have efficient catalysts for implementation in energy conversion devices that could be employed to efficiently store energy from discontinuous renewable sources in chemical bonds (e.g. molecular H2) as a fuel and recover that energy when required.
Protein film electrochemistry (PFE) has been proven as a highly useful technique to study immobilized hydrogenases to gain fundamental information about the enzyme kinetics and their sensitivity towards inhibitors such as O2 and CO.2-3 Much less is known about homogeneous bio-inspired catalysts. In recent years, there has been significant improvement in the development of bio-inspired synthetic catalysts based on earth abundant metals like Fe, Ni or Co. These catalysts have so far been studied using methods very different from the ones used with enzymes. We have shown that we can immobilize some of these catalysts on electrodes and characterize them under conditions mimicking those of a device e.g. a fuel cell or a H2 producing electrode. We can now also compare the activity of the bio-inspired catalysts for H2 oxidation with the enzyme (Figure 1).4-5
When designing an immobilization strategy for a catalyst on an electrode, it is possible to improve the electron transfer between catalyst and electrode and the stability of the catalytic currents. But for delicate catalysts as hydrogenases, sensible to oxidative inactivation, directly interfacing the catalyst with the electrode leads to a rapid loss of electrocatalytic current when the catalyst is exposed to a harsh environment, as is found in an operating fuel cell. In the last years, together with our colleagues at the Ruhr University in Bochum, Wolfgang Schuhmann and Nicolas Plumeré, we have specifically designed redox polymers to protect sensitive hydrogenases from oxidative inactivation and demonstrated the protection mechanism (Figure 2).6-8
Immobilizationof catalysts on electrode surfaces allows precise redox control of theimmobilized molecules and measurements of catalytic currents. On the otherhand, electrochemistry alone does not provide information about the electronicstructure of the immobilized catalysts. Therefore, we combine electrochemistrywith spectroscopy to obtain information from immobilized catalysts underturnover conditions. Combination of IR spectroscopy with PFE can be achievedusing surface-enhanced infrared absorption spectroscopy (SEIRA).9
In collaborationwith the Savitsky and Cox groups, we are currently developing insitu spectroelectrochemical cells for EPR, pulse and continuous wave, X and Q-band to detect paramagneticspecies participating in catalysis from electrode immobilized catalysts.