Identification of Photoexcited Electron Relaxation in a Cobalt Phosphide Modified Carbon Nitride Photocatalyst

Guang X. Pei; Nelson Y. Dzade; Yue Zhang; Jan P. Hofmann; Nora H. de Leeuw; Bert M. Weckhuysen

doi:10.1002/cptc.202000259

Identification of Photoexcited Electron Relaxation in a Cobalt Phosphide Modified Carbon Nitride Photocatalyst

Guang X. Pei, Nelson Y. Dzade, Yue Zhang, Jan P. Hofmann, Nora H. de Leeuw, Bert M. Weckhuysen (Corresponding author)

Inorganic Materials & Catalysis

Research output: Contribution to journal › Article › Academic › peer-review

8 Citations (Scopus)

Abstract

Transition metal phosphides have been recognized as efficient co-catalysts to boost the activity of semiconductor photocatalysts. However, a rigorous and quantitative understanding is still to be developed about how transition metal phosphides influence photoexcited electron dynamics. Here, we present a nanosecond time-resolved transient absorption spectroscopy (TAS) study of the photoexcited electron dynamics in carbon nitrides (g-C₃N₄) before and after Co and/or P modifications. Our spectroscopic study showed that Co or P lowered the initial electron density, whereas they promoted the photoexcited electron relaxation of g-C₃N₄, with their half-life times (t_50%) of 2.5 and 1.8 ns, respectively. The formation of a CoP co-catalyst compound promoted the electron relaxation (t_50%=2.8 ns) without significantly lowering the charge separation efficiency. Density functional theory (DFT) calculations were undertaken to explore the underlying fundamental reasons and they further predicted that CoP, compared to Co or P modification, better facilitates photoexcited electron transfer from g-C₃N₄ to reactants.

Original language	English
Pages (from-to)	330-334
Number of pages	5
Journal	ChemPhotoChem
Volume	5
Issue number	4
DOIs	https://doi.org/10.1002/cptc.202000259
Publication status	Published - Apr 2021

Funding

This work is part of the program “CO‐neutral fuels” (project 13‐CO26) of the Foundation for Fundamental Research on Matter (FOM), which was financially supported by the Netherlands Organization for Scientific Research (NWO). Additional support comes from the NWO Graduate Program “Solar Fuels Catalysis”. Authors are also grateful to Petra Keijzer (Utrecht University, UU) for assistance with the TEM measurements, and Coen Mulder (UU) for performing ICP‐AES measurements. NYD acknowledges the UK Engineering and Physical Sciences Research Council (EPSRC) for funding (Grant No. EP/S001395/1). This work has used the computational facilities of the Advanced Research Computing at Cardiff (ARCCA) Division, Cardiff University, and HPC Wales. 2

Keywords

carbon nitride
cobalt phosphide
electron relaxation
photocatalysis
transient absorption spectroscopy

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10.1002/cptc.202000259

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title = "Identification of Photoexcited Electron Relaxation in a Cobalt Phosphide Modified Carbon Nitride Photocatalyst",

abstract = "Transition metal phosphides have been recognized as efficient co-catalysts to boost the activity of semiconductor photocatalysts. However, a rigorous and quantitative understanding is still to be developed about how transition metal phosphides influence photoexcited electron dynamics. Here, we present a nanosecond time-resolved transient absorption spectroscopy (TAS) study of the photoexcited electron dynamics in carbon nitrides (g-C3N4) before and after Co and/or P modifications. Our spectroscopic study showed that Co or P lowered the initial electron density, whereas they promoted the photoexcited electron relaxation of g-C3N4, with their half-life times (t50%) of 2.5 and 1.8 ns, respectively. The formation of a CoP co-catalyst compound promoted the electron relaxation (t50%=2.8 ns) without significantly lowering the charge separation efficiency. Density functional theory (DFT) calculations were undertaken to explore the underlying fundamental reasons and they further predicted that CoP, compared to Co or P modification, better facilitates photoexcited electron transfer from g-C3N4 to reactants.",

keywords = "carbon nitride, cobalt phosphide, electron relaxation, photocatalysis, transient absorption spectroscopy",

author = "Pei, {Guang X.} and Dzade, {Nelson Y.} and Yue Zhang and Hofmann, {Jan P.} and {de Leeuw}, {Nora H.} and Weckhuysen, {Bert M.}",

year = "2021",

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AU - Pei, Guang X.

AU - Dzade, Nelson Y.

AU - Zhang, Yue

AU - Hofmann, Jan P.

AU - de Leeuw, Nora H.

AU - Weckhuysen, Bert M.

PY - 2021/4

Y1 - 2021/4

N2 - Transition metal phosphides have been recognized as efficient co-catalysts to boost the activity of semiconductor photocatalysts. However, a rigorous and quantitative understanding is still to be developed about how transition metal phosphides influence photoexcited electron dynamics. Here, we present a nanosecond time-resolved transient absorption spectroscopy (TAS) study of the photoexcited electron dynamics in carbon nitrides (g-C3N4) before and after Co and/or P modifications. Our spectroscopic study showed that Co or P lowered the initial electron density, whereas they promoted the photoexcited electron relaxation of g-C3N4, with their half-life times (t50%) of 2.5 and 1.8 ns, respectively. The formation of a CoP co-catalyst compound promoted the electron relaxation (t50%=2.8 ns) without significantly lowering the charge separation efficiency. Density functional theory (DFT) calculations were undertaken to explore the underlying fundamental reasons and they further predicted that CoP, compared to Co or P modification, better facilitates photoexcited electron transfer from g-C3N4 to reactants.

AB - Transition metal phosphides have been recognized as efficient co-catalysts to boost the activity of semiconductor photocatalysts. However, a rigorous and quantitative understanding is still to be developed about how transition metal phosphides influence photoexcited electron dynamics. Here, we present a nanosecond time-resolved transient absorption spectroscopy (TAS) study of the photoexcited electron dynamics in carbon nitrides (g-C3N4) before and after Co and/or P modifications. Our spectroscopic study showed that Co or P lowered the initial electron density, whereas they promoted the photoexcited electron relaxation of g-C3N4, with their half-life times (t50%) of 2.5 and 1.8 ns, respectively. The formation of a CoP co-catalyst compound promoted the electron relaxation (t50%=2.8 ns) without significantly lowering the charge separation efficiency. Density functional theory (DFT) calculations were undertaken to explore the underlying fundamental reasons and they further predicted that CoP, compared to Co or P modification, better facilitates photoexcited electron transfer from g-C3N4 to reactants.

KW - carbon nitride

KW - cobalt phosphide

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KW - transient absorption spectroscopy

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Identification of Photoexcited Electron Relaxation in a Cobalt Phosphide Modified Carbon Nitride Photocatalyst

Abstract

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Keywords

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