TY - JOUR
T1 - Understanding Diffusional Charge Transport within a Pyrene-Based Hydrogen-Bonded Organic Framework
AU - Goswami, Subhadip
AU - Ma, Kaikai
AU - Duan, Jiaxin
AU - Kirlikovali, Kent O.
AU - Bai, Jiaquan
AU - Hupp, Joseph T.
AU - Li, Peng
AU - Farha, Omar K.
N1 - Funding Information:
Authors acknowledge the financial support from the Defense Threat Reduction Agency under award no HDTRA1-19-1-0010. Specifically for conductivity, charge-diffusion, redox-hopping, and electrochromism studies, S.G., J.D., and J.T.H. acknowledge support from the U.S. Department of Energy, Office of Science, Basic Energy Sciences via grant DE-FG02-08ER15967, and from Northwestern University. K.O.K. gratefully acknowledges support from the IIN Postdoctoral Fellowship and the Northwestern University International Institute for Nanotechnology. This work made use of the IMSERC at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205), the State of Illinois, and the International Institute for Nanotechnology (IIN).
Publisher Copyright:
© 2022 American Chemical Society
PY - 2022/2/1
Y1 - 2022/2/1
N2 - Electrochemically active hydrogen-bonded organic frameworks (HOFs) offer opportunities to study charge transport in supramolecular systems where the rate of movement of charges is dependent on weak electronic coupling between individual components. Here, we used potential-step chronoamperometric measurements on electrochemically active, drop-cast HOF-102 films to estimate both redox-hopping-based apparent diffusion coefficients for charge transport and rate constants for linker-to-linker charge transfer (hole transfer) in the mesoporous two-dimensional (2D) plane created by interlinker hydrogen bonding. Also present are one-dimensional columns formed by stacking pyrene units. However, because the HOF-102 crystallites containing these columns are oriented parallel to an underlying electrode, dynamics of charge transport (hole-transport) along the column axis, in contrast to the plane, are not directly probed by the electrochemical measurements. Furthermore, we employed electrochemical impedance spectroscopy to measure the electrical conductivity of the as-deposited films biased at various potentials. We found that both the neutral/singly oxidized and the singly oxidized/doubly oxidized pyrene linker redox couples of HOF-102 can engender hopping-based film conductivity within the 2D plane of HOF-102. Consistent with the radical cation and radical dication nature of the singly and doubly oxidized linkers, respectively, HOF-102 films are electrochromic. The measured values of in-plane charge-diffusion coefficients (∼10–10 to 10–11 cm2 s–1) and electrical conductivity (∼10–6 to 10–8 S cm–1) compare favorably with those for related redox-conductive MOFs and suggest that the transport and conductivity parameters for HOF-102 are sufficiently large to support electrocatalysis by subsequently installed catalysts in films─specifically, films of micron or greater thickness, corresponding to the equivalent hundreds of monolayers of closely packed (i.e., face-to-face-packed) pyrene-derivatives, but with solution access (solvent, ion, and reactant access) still readily provided by channels oriented parallel to an underlying planar electrode.
AB - Electrochemically active hydrogen-bonded organic frameworks (HOFs) offer opportunities to study charge transport in supramolecular systems where the rate of movement of charges is dependent on weak electronic coupling between individual components. Here, we used potential-step chronoamperometric measurements on electrochemically active, drop-cast HOF-102 films to estimate both redox-hopping-based apparent diffusion coefficients for charge transport and rate constants for linker-to-linker charge transfer (hole transfer) in the mesoporous two-dimensional (2D) plane created by interlinker hydrogen bonding. Also present are one-dimensional columns formed by stacking pyrene units. However, because the HOF-102 crystallites containing these columns are oriented parallel to an underlying electrode, dynamics of charge transport (hole-transport) along the column axis, in contrast to the plane, are not directly probed by the electrochemical measurements. Furthermore, we employed electrochemical impedance spectroscopy to measure the electrical conductivity of the as-deposited films biased at various potentials. We found that both the neutral/singly oxidized and the singly oxidized/doubly oxidized pyrene linker redox couples of HOF-102 can engender hopping-based film conductivity within the 2D plane of HOF-102. Consistent with the radical cation and radical dication nature of the singly and doubly oxidized linkers, respectively, HOF-102 films are electrochromic. The measured values of in-plane charge-diffusion coefficients (∼10–10 to 10–11 cm2 s–1) and electrical conductivity (∼10–6 to 10–8 S cm–1) compare favorably with those for related redox-conductive MOFs and suggest that the transport and conductivity parameters for HOF-102 are sufficiently large to support electrocatalysis by subsequently installed catalysts in films─specifically, films of micron or greater thickness, corresponding to the equivalent hundreds of monolayers of closely packed (i.e., face-to-face-packed) pyrene-derivatives, but with solution access (solvent, ion, and reactant access) still readily provided by channels oriented parallel to an underlying planar electrode.
UR - http://www.scopus.com/inward/record.url?scp=85123823831&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85123823831&partnerID=8YFLogxK
U2 - 10.1021/acs.langmuir.1c02915
DO - 10.1021/acs.langmuir.1c02915
M3 - Article
C2 - 35049315
AN - SCOPUS:85123823831
SN - 0743-7463
VL - 38
SP - 1533
EP - 1539
JO - Langmuir
JF - Langmuir
IS - 4
ER -