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In‐situ detection of cobaloxime intermediates during photocatalysis using hollow‐core photonic crystal fiber microreactors

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Lawson, Takashi 
Gentleman, Alexander S 
Pinnell, Jonathan 
Eisenschmidt, Annika 
Antón-García, Daniel 


Hollow-core photonic crystal fibers (HC-PCFs) provide a novel approach for in-situ UV-Vis spectroscopy with enhanced detection sensitivity. Here, we demonstrate that longer optical path lengths than afforded by conventional cuvette-based UV-Vis spectroscopy can be used to detect and identify the Co(I) and Co(II) states in hydrogen-evolving cobaloxime catalysts, with spectral identification aided by comparison with DFT-simulated spectra. Our findings show that there are two types of signals observed for these molecular catalysts; a transient signal and a steady-state signal, with the former being assigned to the Co(I) state and the latter being assigned to the Co(II) state. These observations lend support to a unimolecular pathway, rather than a bimolecular pathway, for hydrogen evolution. This study highlights the utility of fiber-based microreactors for understanding these and a much wider range of homogeneous photocatalytic systems of the future.



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Angewandte Chemie

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Leverhulme Trust (RPG-2018-256)
Engineering and Physical Sciences Research Council (EP/S022953/1)
Engineering and Physical Sciences Research Council (EP/M508007/1)
Engineering and Physical Sciences Research Council (EP/L015978/1)
Engineering and Physical Sciences Research Council (1948662)
EPSRC (1948662)
T.G.E. acknowledges the support from the Winton Programme for the Physics of Sustainability and the Isaac Newton Trust. T.L. and E.R. acknowledge the Cambridge NanoDTC (EPSRC Grant EP/L015978/1 and EP/S022953). A. E. acknowledges the German National Academy of Sciences Leopoldina for a postdoctoral fellowship (LPDS 2018-04). J.P. acknowledges support from the Harding Distinguished Postgraduate Scholars Programme. D. A.-G. acknowledges support from an EPSRC PhD DTA studentship (EP/M508007/1). M.H.F. acknowledges support from the Max-Planck-Gesellschaft. T.G.E, A.S.G., and E.R. acknowledge the Leverhulme Trust (Research Project Grant RPG-2018-256).
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