Towards room-temperature H2 generation from C1-molecules and H2O

Towards room-temperature H2 generation from C1-molecules and H2O

Leo E. Heim, Nils E. Schlörer, Jong-Hoo Choi, Martin H. G. Prechtl
University of Cologne, Department of Chemistry, Greinstr. 6, 50939 Köln, Germany.

For findings towards new energy storage systems, an intensively studied fuel molecule is H2 owing its high energy content, and the possibility to store it in form of hydridic and protic hydrogen.1,2 Recently, we showed that water in presence of C1-entities like (para)formaldehyde (FA) is suitable for molecular hydrogen-storage as these molecules can be easily and selectively dehydrogenated forming pure H2 and CO2.3 The reaction runs on air using a novel water-stable molecular catalyst under base-free conditions. Both molecules, H2O and H2CO, act equally as source of H2. Isotope-labelling experiments (2H, 13C and 18O) confirm that the H2 released originates from both, H2O (H218O or D2O) and H2CO (2H and 13C-labelled). Isotope-labelled complexes and gaseous products could be assigned by means of NMR, ESI-MS and continuous gas-phase MS. A theoretical efficiency of 8.4 wt% of H2 considering 1 eq. H2O and H2CO is possible. This is higher than for formic acid (4.4 wt%), even when technical aq. H2CO is used, the solution has a min. efficiency of 5.0 wt%. This catalytic decomposition of H2CO can be envisioned as novel approach for simultaneous H2 production and decontamination treatment of wastewater with formaldehyde impurities a waste to value approach. Currently, we perform experimental and theoretical mechanistic studies, and develop novel catalysts towards room-temperature H2 generation from water and C1-molecules in general.4

Acknowledgement: MIWF-NRW is acknowledged for the Scientist Returnee Award 2009 and we are grateful for the Ernst-Haage Foundation Prize 2014 of the Max-Planck-Institute for Chemical Energy Conversion.

References

1 L. Schlapbach, A. Zuttel, Nature 2001, 414, 353-358.

2 R. E. Rodríguez-Lugo, M. Trincado, M. Vogt, F. Tewes, G. Santiso-Quinones, H. Grützmacher, Nature Chem. 2013, 5, 342-347.

3 L. E. Heim, N. E. Schloerer, J.-H. Choi, M. H. G. Prechtl, Nature Commun. 2014, 5, Article number: 3621.

4 a) M. H. G. Prechtl et al., manuscript submitted 2015. b) Manuscripts in preparation.