Research output: Contribution to journal › Article › peer-review
Enhancement of Proton Conductivity in Nonporous Metal-Organic Frameworks : The Role of Framework Proton Density and Humidity. / Pili, Simona; Rought, Peter; Kolokolov, Daniil I. et al.
In: Chemistry of Materials, Vol. 30, No. 21, 13.11.2018, p. 7593-7602.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Enhancement of Proton Conductivity in Nonporous Metal-Organic Frameworks
T2 - The Role of Framework Proton Density and Humidity
AU - Pili, Simona
AU - Rought, Peter
AU - Kolokolov, Daniil I.
AU - Lin, Longfei
AU - Da Silva, Ivan
AU - Cheng, Yongqiang
AU - Marsh, Christopher
AU - Silverwood, Ian P.
AU - García Sakai, Victoria
AU - Li, Ming
AU - Titman, Jeremy J.
AU - Knight, Lyndsey
AU - Daemen, Luke L.
AU - Ramirez-Cuesta, Anibal J.
AU - Tang, Chiu C.
AU - Stepanov, Alexander G.
AU - Yang, Sihai
AU - Schröder, Martin
PY - 2018/11/13
Y1 - 2018/11/13
N2 - Owing to their inherent pore structure, porous metal-organic frameworks (MOFs) can undergo postsynthetic modification, such as loading extra-framework proton carriers. However, strategies for improving the proton conductivity for nonporous MOFs are largely lacking, although increasing numbers of nonporous MOFs exhibit promising proton conductivities. Often, high humidity is required for nonporous MOFs to achieve high conductivities, but to date no clear mechanisms have been experimentally identified. Here we describe the new materials MFM-550(M), [M(HL1)], (H4L1 = biphenyl-4,4′-diphosphonic acid; M = La, Ce, Nd, Sm, Gd, Ho), MFM-550(Ba), [Ba(H2L1)], and MFM-555(M), [M(HL2)], (H4L2 = benzene-1,4-diphosphonic acid; M = La, Ce, Nd, Sm, Gd, Ho), and report enhanced proton conductivities in these nonporous materials by (i) replacing the metal ion to one with a lower oxidation state, (ii) reducing the length of the organic ligand, and (iii) introducing additional acidic protons on the MOF surface. Increased framework proton density in these materials can lead to an enhancement in proton conductivity of up to 4 orders of magnitude. Additionally, we report a comprehensive investigation using in situ 2H NMR and neutron spectroscopy, coupled with molecular dynamic modeling, to elucidate the role of humidity in assembling interconnected networks for proton hopping. This study constructs a relationship between framework proton density and the corresponding proton conductivity in nonporous MOFs, and directly explains the role of both surface protons and external water in assembling the proton conduction pathways.
AB - Owing to their inherent pore structure, porous metal-organic frameworks (MOFs) can undergo postsynthetic modification, such as loading extra-framework proton carriers. However, strategies for improving the proton conductivity for nonporous MOFs are largely lacking, although increasing numbers of nonporous MOFs exhibit promising proton conductivities. Often, high humidity is required for nonporous MOFs to achieve high conductivities, but to date no clear mechanisms have been experimentally identified. Here we describe the new materials MFM-550(M), [M(HL1)], (H4L1 = biphenyl-4,4′-diphosphonic acid; M = La, Ce, Nd, Sm, Gd, Ho), MFM-550(Ba), [Ba(H2L1)], and MFM-555(M), [M(HL2)], (H4L2 = benzene-1,4-diphosphonic acid; M = La, Ce, Nd, Sm, Gd, Ho), and report enhanced proton conductivities in these nonporous materials by (i) replacing the metal ion to one with a lower oxidation state, (ii) reducing the length of the organic ligand, and (iii) introducing additional acidic protons on the MOF surface. Increased framework proton density in these materials can lead to an enhancement in proton conductivity of up to 4 orders of magnitude. Additionally, we report a comprehensive investigation using in situ 2H NMR and neutron spectroscopy, coupled with molecular dynamic modeling, to elucidate the role of humidity in assembling interconnected networks for proton hopping. This study constructs a relationship between framework proton density and the corresponding proton conductivity in nonporous MOFs, and directly explains the role of both surface protons and external water in assembling the proton conduction pathways.
KW - COORDINATION POLYMERS
KW - WATER-MOLECULES
KW - DIFFUSION
KW - SORPTION
KW - SITES
UR - http://www.scopus.com/inward/record.url?scp=85056604299&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.8b02765
DO - 10.1021/acs.chemmater.8b02765
M3 - Article
AN - SCOPUS:85056604299
VL - 30
SP - 7593
EP - 7602
JO - Chemistry of Materials
JF - Chemistry of Materials
SN - 0897-4756
IS - 21
ER -
ID: 17409900