MOF derived mesoporous K-ZrO<sub>2</sub> with enhanced basic catalytic performance for Knoevenagel condensations

Wang, Peng; Feng, Jian; Zhao, Yupei; Gu, Sai; Liu, Jian

doi:10.1039/c7ra12378g

Cited by 13 publications

(7 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the plateaus generally do not reach the ideal weights, which suggests that the real Zr 6 O 6 (BDC) 6 and Zr 6 O 6 (BDC-NH 2 ) 6 frameworks are lighter than the ideal ones (Figure a), and some linkers are missed. The numbers of the missed linkers per Zr 6 node can be calculated by the following rearranged equations based on the reported ones ,− and for UiO-66 and UiO-66-NH 2 , respectively. The results show that ∼1.15 and ∼0.46 linkers per Zr 6 node are missed in UiO-66-NH 2 and UiO-66 respectively, using acetic acid as a typical defect modulator. − It suggests that UiO-66-NH 2 is favorable for missing linkers in comparison with UiO-66, which is due to the weaker coordination of 2-aminoterephthalic acid to the Zr 6 node as compared with the terephthalic one .…”

Section: Results and Discussionmentioning

confidence: 99%

Defective UiO-66-NH₂ Functionalized with Stable Superoxide Radicals toward Electrocatalytic Nitrogen Reduction with High Faradaic Efficiency

Yin

et al. 2022

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

The electrocatalytic nitrogen reduction reaction (NRR) to NH 3 is limited by low Faradaic efficiency (FE). Herein, defective UiO-66-NH 2 functionalized with quite stable superoxide radicals (O 2• ) is developed as a highly active NRR catalyst. The experimental and computational results show that one linker per Zr 6 node is missed and two Zr atoms are exposed in the defective UiO-66-NH 2 . One of the two exposed Zr atoms can stably adsorb O 2• , and thus, a Zr-OO • site forms during the preparations without light excitation or postoxidation, while the other Zr atom is activated as an active site. The synergistic effects of the two Zr sites in the defective UiO-66-NH 2 suppress hydrogen and hydrazine evolutions considerably. They are as follows: (i) due to repulsion of the proton on the active Zr site and stabilization of the proton on the Zr-OO • site, the active Zr site is unfavorable for the adsorption of the proton with a high energy barrier, which is the HER rate-determining step (RDS); (ii) under the assistance of the OO • of the Zr-OO • site, the first hydrogenation step of *N 2 (i.e., NRR RDS) on the active Zr site is promoted; and (iii) relying on the assistance of the OO • of the Zr-OO • site, the continuous hydrogenation of *NH 2 NH 2 to produce NH 3 on the active Zr site is spontaneously exothermic, whereas its desorption to hydrazine is blocked. Accordingly, an extremely high FE of ∼85.21% has been realized along with a high yield rate of NH 3 (∼52.81 μg h −1 mg cat −1 ). To the best of our knowledge, it is the highest FE that has been achieved in recent years. Radical scavenging treatment of the defective UiO-66-NH 2 and detailed investigations of two categories of control samples further verify the favorable effects of the O 2• that closely correlates with the missed linkers on the performance of the NRR to NH 3 . This work opens a new way toward highly efficient NRR catalysts, i.e., stable radical-activating defective metal− organic frameworks.

show abstract

Section: Results and Discussionmentioning

confidence: 99%

Defective UiO-66-NH₂ Functionalized with Stable Superoxide Radicals toward Electrocatalytic Nitrogen Reduction with High Faradaic Efficiency

Yin

et al. 2022

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

show abstract

“…The temperature-programmed desorption analysis using CO 2 probe gas (CO 2 -TPD) was also performed to estimate the concentration of accessible Lewis basic sites and qualitatively determine the different types of basic sites. The activated I was treated with CO 2 as a form of CO 2 /He mixture (10% CO 2 ) at 30 • C for 1 h. The CO 2 -TPD curve shown in Figure S7 indicates that there are several desorption signals below 253 • C. This range of values has been attributed to weak basic sites (Wang et al, 2017). Furthermore, the total integrated area indicates the concentration of basic sites is about 0.022 mmol g −1 .…”

Section: X-ray Crystallographymentioning

confidence: 99%

Gas Sorption Properties of a New Three-Dimensional In-ABDC MOF With a Diamond Net

et al. 2019

View full text Add to dashboard Cite

The pseudotetrahedral node, [In(O 2 CR) 4 ] − , often found in In III-based metal-organic frameworks (MOFs) without a cluster-based secondary building unit (SBU) is a negatively charged center due to charge mismatch between an 8-coordinate In III ion and four anionic carboxylate bridging ligands. Thus, In-MOFs with this pseudotetrahedral node tend to bear a counter-cation near each In III center in the frameworks. Generally, dialkylammonium-based cations such as Me 2 NH + 2 and Et 2 NH + 2 directly derived from N,N-dimethylformamide (DMF) or N,N-diethylformamide (DEF) solvents during MOF formation reactions play a significant role to form a stable framework through charge matching. If these cations thermally derived from DMF or DEF were not suitable for crystal growth of In-MOFs, it becomes very challenging to obtain high quality single crystals for X-ray structure determination of the frameworks. In this context, high quality crystals of In-ABDC MOF were not easily prepared from a ditopic azobenzene-4,4'-dicarboxylic acid (H 2 ABDC) through a thermal reaction in DMF or DEF. We successfully overcome this problem by employing a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF 4 ]), and the resulting three-dimensional (3D) In-ABDC MOF, [EMIM][In(ABDC) 2 ]•DEF•H 2 O (I), was structurally characterized by X-ray diffraction. The 3D framework indicates a 4-connected uninodal net with Schläfli symbol of 6 6 (dia). The gas sorption properties of solvent-free I were also investigated in detail.

show abstract

“…[13][14][15] Metals, especially transition metals, have been extensively applied in a series of important organic transformations as heterogeneous catalysts such as nanoparticles (NPs), metalorganic framework (MOF), clusters, coordination metal complexes, or free ions. [16][17][18][19][20][21] Despite their high efficiency, these catalysts have some drawbacks such as significant environmental effects, metal leaching, high price, gas poisoning susceptibility, poor durability, and low selectivity. Thus, metal-free, and recyclable catalysts are crucial for both environmental remediation and large-scale industrial applications.…”

Section: Introductionmentioning

confidence: 99%

An overview of metal-free sustainable nitrogen-based catalytic knoevenagel condensation reaction

2022

View full text Add to dashboard Cite

show abstract

MOF derived mesoporous K-ZrO₂ with enhanced basic catalytic performance for Knoevenagel condensations

Abstract: Mesoporous K-ZrO2 (KZ) was synthesized from KNO3-loaded UiO-66 with two-step heat treatment, showing enhanced catalytic performance in conversion of substrates with large molecular sizes.

Cited by 13 publications

References 31 publications

Defective UiO-66-NH₂ Functionalized with Stable Superoxide Radicals toward Electrocatalytic Nitrogen Reduction with High Faradaic Efficiency

Defective UiO-66-NH₂ Functionalized with Stable Superoxide Radicals toward Electrocatalytic Nitrogen Reduction with High Faradaic Efficiency

Gas Sorption Properties of a New Three-Dimensional In-ABDC MOF With a Diamond Net

An overview of metal-free sustainable nitrogen-based catalytic knoevenagel condensation reaction

Contact Info

Product

Resources

About

MOF derived mesoporous K-ZrO2 with enhanced basic catalytic performance for Knoevenagel condensations

Abstract: Mesoporous K-ZrO2 (KZ) was synthesized from KNO3-loaded UiO-66 with two-step heat treatment, showing enhanced catalytic performance in conversion of substrates with large molecular sizes.

Cited by 13 publications

References 31 publications

Defective UiO-66-NH2 Functionalized with Stable Superoxide Radicals toward Electrocatalytic Nitrogen Reduction with High Faradaic Efficiency

Defective UiO-66-NH2 Functionalized with Stable Superoxide Radicals toward Electrocatalytic Nitrogen Reduction with High Faradaic Efficiency

Gas Sorption Properties of a New Three-Dimensional In-ABDC MOF With a Diamond Net

An overview of metal-free sustainable nitrogen-based catalytic knoevenagel condensation reaction

Contact Info

Product

Resources

About

MOF derived mesoporous K-ZrO₂ with enhanced basic catalytic performance for Knoevenagel condensations

Defective UiO-66-NH₂ Functionalized with Stable Superoxide Radicals toward Electrocatalytic Nitrogen Reduction with High Faradaic Efficiency

Defective UiO-66-NH₂ Functionalized with Stable Superoxide Radicals toward Electrocatalytic Nitrogen Reduction with High Faradaic Efficiency