Metal-organic framework-derived ZrO2 on N/S-doped porous carbons for mechanistic and kinetic inspection of catalytic H2O2 homolysis

Minsung Kim; Jinseon Park; Sang Hoon Kim; Jung Hyun Lee; Keunhong Jeong; Jongsik Kim

doi:10.1016/j.carbon.2022.12.023

Metal-organic framework-derived ZrO₂ on N/S-doped porous carbons for mechanistic and kinetic inspection of catalytic H₂O₂ homolysis

Minsung Kim, Jinseon Park, Sang Hoon Kim, Jung Hyun Lee, Keunhong Jeong, Jongsik Kim

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

13 Citations (Scopus)

Abstract

Homolytic and heterolytic H₂O₂ scissions are central to produce ^•OH for aqueous contaminant fragmentation. However, the kinetic, mechanistic, and energetic aspects of homolytic H₂O₂ cleavage remain under-explored, providing impetus for research with the use of difficult-to-degrade phenol as a model pollutant. Herein, UiO-66 and its analogues functionalized with –NH₂/-SO₃H (UiO-66-NH₂/UiO-66-SO₃H) were synthesized to generate ZrO₂ poly-crystallites on N/S-doped carbon catalysts via pyrolysis (C_UiO-66/C_UiO-66-NH2/C_UiO-66-SO3H). The catalyst surfaces contained distinct concentrations of Lewis basic N/S dopants, which donated electrons to adjacent Brönsted acidic –OH (BA) and Lewis acidic Zr⁴⁺ (LA) species dissimilarly, resulting in the catalysts with diverse BA/LA strengths (E_BA/E_LA) and areas (S_BA/S_LA). C_UiO-66 exhibited the highest E_LA and lowest E_BA, which are favorable for endothermic H₂O₂ distortion, whereas C_UiO-66-SO3H exhibited the lowest E_LA and highest E_BA, with only E_BA being favorable for endothermic ^•OH desorption, while leaving the other elementary steps exothermic. Kinetic analysis and DFT calculations revealed that C_UiO-66-SO3H possessed the lowest energy barrier (E_BARRIER), demonstrating ^•OH desorption was the rate-determining step alongside with the significance of high E_BA for reducing E_BARRIER. Meanwhile, the highest pre-factor was observed for C_UiO-66 with the largest S_LA, corroborating the significance of large S_LA for escalating the collision frequency between Zr⁴⁺ and H₂O₂/^•OH. These results boost to adjust E_BA/S_LA for promoting ^•OH productivity via catalytic H₂O₂ homolysis.

Original language	English
Pages (from-to)	630-649
Number of pages	20
Journal	Carbon
Volume	203
DOIs	https://doi.org/10.1016/j.carbon.2022.12.023
Publication status	Published - 2023 Jan 25

Bibliographical note

Funding Information:
Hence, the moderate reusability of the catalysts could be ascribed to the generation of oligomeric phenols and their continuous deposition on the BA or LA sites of the ZrO2 clusters. Oligomeric phenols might act as poisons to significantly reduce the •OH productivities of the catalysts during the recycle runs. This was partially evidenced by the SN2 and VMICRO values of the used catalysts, which plummeted up to <20 m2 gCAT−1 and 0 cm3 gCAT−1, respectively, post the 3rd recycle runs (Table S11). This was con-current to the XRD patterns of the used catalysts, which showed that the intensities of the prime diffractions for tetragonal ZrO2 (crystallinities) with 2θ values centered at 30–35° were continuously declined post each of the recycle runs ((101), (110), (002) in Fig. S19). Moreover, the EDX spectra of the used catalysts also revealed a gradual increase in the atomic ratios of C/Zr post each of the recycle runs (e.g., C/Zr of 4.9 → 7.9 for CUiO-66 in Fig. 15B–D). This substantiated that the surface poison incurred by oligomeric phenols became increasingly severe post each of the recycle runs. In addition to disclosing intermediates that were potentially mineralized to form CO2 and H2O (Fig. S25) [ 89–93], the LC-MS spectra of the reaction solutions collected post the recycle runs proved the generation of phenol dimers and trimers potentially via H• abstraction/coupling and •OH addition/dehydration/coupling, respectively (Fig. 15A) [ 89–93]. The production of oligomeric poisons initiated by H• abstraction/•OH addition appeared to be imperative in the •OH-mediated degradation of refractory aromatics. However, this could be avoided by altering the function of •OH from aromatic decomposer to radicalizer of supported SO42−/NO3− located near the BA or LA sites of ZrO2. •OH could generate supported SO4•-/NO3• species via radical transfer [ 4–7], which could degrade aromatics primarily via electron transfer, while minimizing the formation of oligomeric poisons.We thank Ministry of Science and ICT and National Research Foundation of South Korea for providing a grant for this project (#NRF-2020R1A2C2004395). We are grateful to Korea Institute of Science and Technology for supporting this project through Future R & D.

Funding Information:
We thank Ministry of Science and ICT and National Research Foundation of South Korea for providing a grant for this project ( #NRF-2020R1A2C2004395 ). We are grateful to Korea Institute of Science and Technology for supporting this project through Future R & D.

Publisher Copyright:
© 2022 Elsevier Ltd

Keywords

Brӧnsted/Lewis acidity
Dopant
Homolytic HO scission
Metal-organic framework
Non-reducible metal
Pyrolysis

ASJC Scopus subject areas

General Chemistry
General Materials Science

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10.1016/j.carbon.2022.12.023

Cite this

@article{8fcb4ac82d1f44a2af819ade66c2b828,

title = "Metal-organic framework-derived ZrO2 on N/S-doped porous carbons for mechanistic and kinetic inspection of catalytic H2O2 homolysis",

abstract = "Homolytic and heterolytic H2O2 scissions are central to produce •OH for aqueous contaminant fragmentation. However, the kinetic, mechanistic, and energetic aspects of homolytic H2O2 cleavage remain under-explored, providing impetus for research with the use of difficult-to-degrade phenol as a model pollutant. Herein, UiO-66 and its analogues functionalized with –NH2/-SO3H (UiO-66-NH2/UiO-66-SO3H) were synthesized to generate ZrO2 poly-crystallites on N/S-doped carbon catalysts via pyrolysis (CUiO-66/CUiO-66-NH2/CUiO-66-SO3H). The catalyst surfaces contained distinct concentrations of Lewis basic N/S dopants, which donated electrons to adjacent Br{\"o}nsted acidic –OH (BA) and Lewis acidic Zr4+ (LA) species dissimilarly, resulting in the catalysts with diverse BA/LA strengths (EBA/ELA) and areas (SBA/SLA). CUiO-66 exhibited the highest ELA and lowest EBA, which are favorable for endothermic H2O2 distortion, whereas CUiO-66-SO3H exhibited the lowest ELA and highest EBA, with only EBA being favorable for endothermic •OH desorption, while leaving the other elementary steps exothermic. Kinetic analysis and DFT calculations revealed that CUiO-66-SO3H possessed the lowest energy barrier (EBARRIER), demonstrating •OH desorption was the rate-determining step alongside with the significance of high EBA for reducing EBARRIER. Meanwhile, the highest pre-factor was observed for CUiO-66 with the largest SLA, corroborating the significance of large SLA for escalating the collision frequency between Zr4+ and H2O2/•OH. These results boost to adjust EBA/SLA for promoting •OH productivity via catalytic H2O2 homolysis.",

keywords = "Brӧnsted/Lewis acidity, Dopant, Homolytic HO scission, Metal-organic framework, Non-reducible metal, Pyrolysis",

author = "Minsung Kim and Jinseon Park and Kim, {Sang Hoon} and Lee, {Jung Hyun} and Keunhong Jeong and Jongsik Kim",

note = "Funding Information: Hence, the moderate reusability of the catalysts could be ascribed to the generation of oligomeric phenols and their continuous deposition on the BA or LA sites of the ZrO2 clusters. Oligomeric phenols might act as poisons to significantly reduce the •OH productivities of the catalysts during the recycle runs. This was partially evidenced by the SN2 and VMICRO values of the used catalysts, which plummeted up to <20 m2 gCAT−1 and 0 cm3 gCAT−1, respectively, post the 3rd recycle runs (Table S11). This was con-current to the XRD patterns of the used catalysts, which showed that the intensities of the prime diffractions for tetragonal ZrO2 (crystallinities) with 2θ values centered at 30–35° were continuously declined post each of the recycle runs ((101), (110), (002) in Fig. S19). Moreover, the EDX spectra of the used catalysts also revealed a gradual increase in the atomic ratios of C/Zr post each of the recycle runs (e.g., C/Zr of 4.9 → 7.9 for CUiO-66 in Fig. 15B–D). This substantiated that the surface poison incurred by oligomeric phenols became increasingly severe post each of the recycle runs. In addition to disclosing intermediates that were potentially mineralized to form CO2 and H2O (Fig. S25) [ 89–93], the LC-MS spectra of the reaction solutions collected post the recycle runs proved the generation of phenol dimers and trimers potentially via H• abstraction/coupling and •OH addition/dehydration/coupling, respectively (Fig. 15A) [ 89–93]. The production of oligomeric poisons initiated by H• abstraction/•OH addition appeared to be imperative in the •OH-mediated degradation of refractory aromatics. However, this could be avoided by altering the function of •OH from aromatic decomposer to radicalizer of supported SO42−/NO3− located near the BA or LA sites of ZrO2. •OH could generate supported SO4•-/NO3• species via radical transfer [ 4–7], which could degrade aromatics primarily via electron transfer, while minimizing the formation of oligomeric poisons.We thank Ministry of Science and ICT and National Research Foundation of South Korea for providing a grant for this project (#NRF-2020R1A2C2004395). We are grateful to Korea Institute of Science and Technology for supporting this project through Future R & D. Funding Information: We thank Ministry of Science and ICT and National Research Foundation of South Korea for providing a grant for this project ( #NRF-2020R1A2C2004395 ). We are grateful to Korea Institute of Science and Technology for supporting this project through Future R & D. Publisher Copyright: {\textcopyright} 2022 Elsevier Ltd",

year = "2023",

month = jan,

day = "25",

doi = "10.1016/j.carbon.2022.12.023",

language = "English",

volume = "203",

pages = "630--649",

journal = "Carbon",

issn = "0008-6223",

publisher = "Elsevier Ltd",

}

TY - JOUR

T1 - Metal-organic framework-derived ZrO2 on N/S-doped porous carbons for mechanistic and kinetic inspection of catalytic H2O2 homolysis

AU - Kim, Minsung

AU - Park, Jinseon

AU - Kim, Sang Hoon

AU - Lee, Jung Hyun

AU - Jeong, Keunhong

AU - Kim, Jongsik

N1 - Funding Information: Hence, the moderate reusability of the catalysts could be ascribed to the generation of oligomeric phenols and their continuous deposition on the BA or LA sites of the ZrO2 clusters. Oligomeric phenols might act as poisons to significantly reduce the •OH productivities of the catalysts during the recycle runs. This was partially evidenced by the SN2 and VMICRO values of the used catalysts, which plummeted up to <20 m2 gCAT−1 and 0 cm3 gCAT−1, respectively, post the 3rd recycle runs (Table S11). This was con-current to the XRD patterns of the used catalysts, which showed that the intensities of the prime diffractions for tetragonal ZrO2 (crystallinities) with 2θ values centered at 30–35° were continuously declined post each of the recycle runs ((101), (110), (002) in Fig. S19). Moreover, the EDX spectra of the used catalysts also revealed a gradual increase in the atomic ratios of C/Zr post each of the recycle runs (e.g., C/Zr of 4.9 → 7.9 for CUiO-66 in Fig. 15B–D). This substantiated that the surface poison incurred by oligomeric phenols became increasingly severe post each of the recycle runs. In addition to disclosing intermediates that were potentially mineralized to form CO2 and H2O (Fig. S25) [ 89–93], the LC-MS spectra of the reaction solutions collected post the recycle runs proved the generation of phenol dimers and trimers potentially via H• abstraction/coupling and •OH addition/dehydration/coupling, respectively (Fig. 15A) [ 89–93]. The production of oligomeric poisons initiated by H• abstraction/•OH addition appeared to be imperative in the •OH-mediated degradation of refractory aromatics. However, this could be avoided by altering the function of •OH from aromatic decomposer to radicalizer of supported SO42−/NO3− located near the BA or LA sites of ZrO2. •OH could generate supported SO4•-/NO3• species via radical transfer [ 4–7], which could degrade aromatics primarily via electron transfer, while minimizing the formation of oligomeric poisons.We thank Ministry of Science and ICT and National Research Foundation of South Korea for providing a grant for this project (#NRF-2020R1A2C2004395). We are grateful to Korea Institute of Science and Technology for supporting this project through Future R & D. Funding Information: We thank Ministry of Science and ICT and National Research Foundation of South Korea for providing a grant for this project ( #NRF-2020R1A2C2004395 ). We are grateful to Korea Institute of Science and Technology for supporting this project through Future R & D. Publisher Copyright: © 2022 Elsevier Ltd

PY - 2023/1/25

Y1 - 2023/1/25

N2 - Homolytic and heterolytic H2O2 scissions are central to produce •OH for aqueous contaminant fragmentation. However, the kinetic, mechanistic, and energetic aspects of homolytic H2O2 cleavage remain under-explored, providing impetus for research with the use of difficult-to-degrade phenol as a model pollutant. Herein, UiO-66 and its analogues functionalized with –NH2/-SO3H (UiO-66-NH2/UiO-66-SO3H) were synthesized to generate ZrO2 poly-crystallites on N/S-doped carbon catalysts via pyrolysis (CUiO-66/CUiO-66-NH2/CUiO-66-SO3H). The catalyst surfaces contained distinct concentrations of Lewis basic N/S dopants, which donated electrons to adjacent Brönsted acidic –OH (BA) and Lewis acidic Zr4+ (LA) species dissimilarly, resulting in the catalysts with diverse BA/LA strengths (EBA/ELA) and areas (SBA/SLA). CUiO-66 exhibited the highest ELA and lowest EBA, which are favorable for endothermic H2O2 distortion, whereas CUiO-66-SO3H exhibited the lowest ELA and highest EBA, with only EBA being favorable for endothermic •OH desorption, while leaving the other elementary steps exothermic. Kinetic analysis and DFT calculations revealed that CUiO-66-SO3H possessed the lowest energy barrier (EBARRIER), demonstrating •OH desorption was the rate-determining step alongside with the significance of high EBA for reducing EBARRIER. Meanwhile, the highest pre-factor was observed for CUiO-66 with the largest SLA, corroborating the significance of large SLA for escalating the collision frequency between Zr4+ and H2O2/•OH. These results boost to adjust EBA/SLA for promoting •OH productivity via catalytic H2O2 homolysis.

AB - Homolytic and heterolytic H2O2 scissions are central to produce •OH for aqueous contaminant fragmentation. However, the kinetic, mechanistic, and energetic aspects of homolytic H2O2 cleavage remain under-explored, providing impetus for research with the use of difficult-to-degrade phenol as a model pollutant. Herein, UiO-66 and its analogues functionalized with –NH2/-SO3H (UiO-66-NH2/UiO-66-SO3H) were synthesized to generate ZrO2 poly-crystallites on N/S-doped carbon catalysts via pyrolysis (CUiO-66/CUiO-66-NH2/CUiO-66-SO3H). The catalyst surfaces contained distinct concentrations of Lewis basic N/S dopants, which donated electrons to adjacent Brönsted acidic –OH (BA) and Lewis acidic Zr4+ (LA) species dissimilarly, resulting in the catalysts with diverse BA/LA strengths (EBA/ELA) and areas (SBA/SLA). CUiO-66 exhibited the highest ELA and lowest EBA, which are favorable for endothermic H2O2 distortion, whereas CUiO-66-SO3H exhibited the lowest ELA and highest EBA, with only EBA being favorable for endothermic •OH desorption, while leaving the other elementary steps exothermic. Kinetic analysis and DFT calculations revealed that CUiO-66-SO3H possessed the lowest energy barrier (EBARRIER), demonstrating •OH desorption was the rate-determining step alongside with the significance of high EBA for reducing EBARRIER. Meanwhile, the highest pre-factor was observed for CUiO-66 with the largest SLA, corroborating the significance of large SLA for escalating the collision frequency between Zr4+ and H2O2/•OH. These results boost to adjust EBA/SLA for promoting •OH productivity via catalytic H2O2 homolysis.

KW - Brӧnsted/Lewis acidity

KW - Dopant

KW - Homolytic HO scission

KW - Metal-organic framework

KW - Non-reducible metal

KW - Pyrolysis

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