Tracking Charge Transfer to Residual Metal Clusters in Conjugated Polymers for Photocatalytic Hydrogen Evolution.
Aitchison, Catherine M
Wilson, Anna A
Cooper, Andrew I
Sprick, Reiner Sebastian
Durrant, James R.
KAUST DepartmentChemical Science Program
Physical Science and Engineering (PSE) Division
KAUST Solar Center (KSC)
KAUST Grant NumberOSR-2015-CRG4-2572
Online Publication Date2020-07-28
Print Publication Date2020-08-26
Embargo End Date2021-08-14
Permanent link to this recordhttp://hdl.handle.net/10754/664753
MetadataShow full item record
AbstractSemiconducting polymers are versatile materials for solar energy conversion and have gained popularity as photocatalysts for sunlight-driven hydrogen production. Organic polymers often contain residual metal impurities such as palladium (Pd) clusters that are formed during the polymerization reaction, and there is increasing evidence for a catalytic role of such metal clusters in polymer photocatalysts. Using transient and operando optical spectroscopy on nanoparticles of F8BT, P3HT, and the dibenzo[b,d]thiophene sulfone homopolymer P10, we demonstrate how differences in the time scale of electron transfer to Pd clusters translate into hydrogen evolution activity optima at different residual Pd concentrations. For F8BT nanoparticles with common Pd concentrations of >1000 ppm (>0.1 wt %), we find that residual Pd clusters quench photogenerated excitons via energy and electron transfer on the femto-nanosecond time scale, thus outcompeting reductive quenching. We spectroscopically identify reduced Pd clusters in our F8BT nanoparticles from the microsecond time scale onward and show that the predominant location of long-lived electrons gradually shifts to the F8BT polymer when the Pd content is lowered. While a low yield of long-lived electrons limits the hydrogen evolution activity of F8BT, P10 exhibits a substantially higher hydrogen evolution activity, which we demonstrate results from higher yields of long-lived electrons due to more efficient reductive quenching. Surprisingly, and despite the higher performance of P10, long-lived electrons reside on the P10 polymer rather than on the Pd clusters in P10 particles, even at very high Pd concentrations of 27000 ppm (2.7 wt %). In contrast, long-lived electrons in F8BT already reside on Pd clusters before the typical time scale of hydrogen evolution. This comparison shows that P10 exhibits efficient reductive quenching but slow electron transfer to residual Pd clusters, whereas the opposite is the case for F8BT. These findings suggest that the development of even more efficient polymer photocatalysts must target materials that combine both rapid reductive quenching and rapid charge transfer to a metal-based cocatalyst.
CitationSachs, M., Cha, H., Kosco, J., Aitchison, C. M., Francàs, L., Corby, S., … Durrant, J. R. (2020). Tracking Charge Transfer to Residual Metal Clusters in Conjugated Polymers for Photocatalytic Hydrogen Evolution. Journal of the American Chemical Society. doi:10.1021/jacs.0c06104
SponsorsM.S. is grateful to Imperial College for a President’s Ph.D. Scholarship and to the EPSRC for a Doctoral Prize Fellowship. J.R.D. and I.M. acknowledge support from KAUST (project numbers OSR-2015-CRG4-2572 and OSR-2018-CRG7-3749.2). C.M.A., A.I.C., and R.S.S. acknowledge the Engineering and Physical Sciences Research Council (EPSRC, EP/N004884/1). L.F. thanks the EU for a Marie Curie fellowship(658270). S.C. thanks Imperial College London for a Schrödinger Scholarship. R.G. is grateful to the FRQNT for a postdoctoral award and NSERC Discovery Grant funding. C.-L.C. appreciates his colleague, Dr. Bing-Jian Su, for his kind support and assistance. All plotted data have been deposited on the open-access repository Zenodo and can be accessed via dx. doi.org/10.5281/zenodo.3932340.
PublisherAmerican Chemical Society (ACS)
RelationsIs Supplemented By:
Sachs, M., Hyojung Cha, Kosco, J., Aitchison, C. M., Francàs, L., Corby, S., Chao-Lung Chiang, Wilson, A. A., Godin, R., Fahey-Williams, A., Cooper, A. I., Sprick, R. S., McCulloch, I., & Durrant, J. R. (2020). Data for article "Tracking Charge Transfer to Residual Metal Clusters in Conjugated Polymers for Photocatalytic Hydrogen Evolution" [Data set]. Zenodo. https://doi.org/10.5281/ZENODO.3932339. DOI: 10.5281/zenodo.3932339 Handle: 10754/664924
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