Structural Investigations of (Ni,Cu) Co–Doped ZnO Nanocrystals by X‐ray Absorption Spectroscopy

Tiwari, Nidhi; Kumar, Shiv; Kamal, C.; Chakrabarti, Aparna; Prajapat, C.L.; Mishra, Pushkar; Mondal, Puspen; Jha, S. N.; Bhattacharyya, D.

doi:10.1002/slct.201800310

Cited by 5 publications

(5 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(Note that “CuO” is used to represent an -oxide equivalent.) This indicates the detachment of single Cu 2+ ions from the framework and their further agglomeration . Linear combination fitting (LCF) was utilized to quantify isolated versus agglomerated Cu 2+ using pristine Cu 20% -ZIF and CuO as standards (the R -factor is below 0.3%).…”

Section: Resultsmentioning

confidence: 99%

“…This indicates the detachment of single Cu 2+ ions from the framework and their further agglomeration. 67 Linear combination fitting (LCF) was utilized to quantify isolated versus agglomerated Cu 2+ using pristine Cu 20% -ZIF and CuO as standards (the R-factor is below 0.3%). After the first cycle (Cu 20% -ZIF-Cat), only 9% Cu 2+ agglomerates; however, as the material is recycled five times (Cu 20% -ZIF-Cat-5X), 27% Cu 2+ is identified as agglomerated species, i.e., ∼5% of the metal ions initially present as nodes.…”

Section: Structure Probing During the Reactionmentioning

confidence: 99%

See 1 more Smart Citation

Bioinspired Cu(II) Defect Sites in ZIF-8 for Selective Methane Oxidation

Yang,

Kanchanakungwankul,

Bhaumik

et al. 2023

J. Am. Chem. Soc.

View full text Add to dashboard Cite

Activating the C−H bonds of alkanes without further oxidation to more thermodynamically stable products, CO and CO 2 , is a long-sought goal of catalytic chemistry. Inspired by the monocopper active site of methane monooxygenase, we synthesized a Cu-doped ZIF-8 metal−organic framework with 25% Cu and 75% Zn in the nodes and activated it by heating to 200 °C and dosing in a stepwise fashion with O 2 , methane, and steam. We found that it does oxidize methane to methanol and formaldehyde. The catalysis persists through at least five cycles, and beyond the third cycle, the selectivity improves to the extent that no CO 2 can be detected. Experimental characterization and analysis were carried out by PXRD, DRUV−vis, SEM, and XAS (XANES and EXAFS). The reaction is postulated to proceed at opencoordination copper sites generated by defects, and the mechanism of methanol production was explicated by density functional calculations with the revMO6-L exchange−correlation functional. The calculations reveal a catalytic cycle of oxygen-activated Cu I involving the conversion of two molecules of CH 4 to two molecules of CH 3 OH by a sequence of hydrogen atom transfer reactions and rebound steps. For most steps in the cycle, the reaction is more favored by singlet species than by triplets.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Structure Probing During the Reactionmentioning

confidence: 99%

Bioinspired Cu(II) Defect Sites in ZIF-8 for Selective Methane Oxidation

Yang,

Kanchanakungwankul,

Bhaumik

et al. 2023

J. Am. Chem. Soc.

View full text Add to dashboard Cite

show abstract

“…The EXAFS data analysis software available within the IFEFFIT package was used for analysis of absorption spectra, which involves the computation of χ (R) spectra (through ATHENA software). In addition, ARTEMIS software was utilized to generate theoretical EXAFS spectra and fitting it with the experimental data [48]. The absorption edge in the XANES spectrum was found to be dependent on the oxidation and electronic state of absorbing atom, along with its atomic level geometry.…”

Section: Resultsmentioning

confidence: 99%

“…One can notice that the pre-edge peak 'A' at ∼8333 eV (figure5(a)) was considered to possess direct dipole transition from Ni 1s states to O 2p states, owing to the effective hybridization as reported in earlier literature[49]. The EXAFS oscillations were analyzed through the earlier-mentioned standard procedure[48].The EXAFS data k 2 χ(k) and its corresponding Fourier transforms are depicted in figures 5(b), (c). k 2 weighted spectra were Fourier transformed at k range 2-8 Å −1 .…”

mentioning

confidence: 88%

Plasmonic Ag nanoparticles arbitrated enhanced photodetection in p-NiO/n-rGO heterojunction for future self-powered UV photodetectors

et al. 2019

View full text Add to dashboard Cite

We report on the low cost and low temperature chemical synthesis of p-type nickel oxide (NiO) and n-type reduced graphene oxide (rGO) and their integration onto ITO/glass substrate to form p-NiO/n-rGO heterojunction for possible self-powered ultraviolet (UV) photodetector applications. Different spectroscopies and microscopes were employed to study their microstructural and surface properties. Whereas, the electrical characterizations have been performed on the devices to ascertain the responsivity, detectivity, external quantum efficiency and temporal responses under dark and UV illumination. It is noteworthy that rGO has not only been used as an n-type semiconductor, but also acted as an electron transport layer, which satisfactorily separates out the electrons from the generated carrier pairs, leading to enhanced photoresponse. Furthermore, efforts were also consecrated to synthesize Ag nanoparticles (NPs) of ∼5 nm radius. The integration of Ag NPs on the conventional NiO/rGO heterojunction facilitates an improved UV light absorption property. It was understood that the performance improvement was owed to the local surface plasmon resonance of Ag NPs within the active layer of NiO. Surprisingly, both the devices (with and without Ag NPs) exhibit photovoltaic behavior which shows its potential for self-powered device application. When the Ag NPs embedded device is concerned, it showed better on/off ratio (6.3 × 103), high responsivity (72 mAW−1), large detectivity (3.95 × 1012 Jones), and high efficiency (24.46%) as compared to the conventional NiO/rGO heterojunction one (without Ag NPs). The variation in the photoresponse and improved charge transport was explained through a band-diagram, which also showcases a comprehensive understanding on the operational principle of the fabricated self-powered devices. Thus, this self-powered photodetector driven by built in electric field is operated independently and can be attached with any other electronic gadgets for internet of things applications.

show abstract

“…This action generates the χ(R) versus R spectra or Fourier transformed EXAFS (FT‐EXAFS) spectra of U‐based samples at U‐L 3 edge, shown in Figure , in terms of the real distances from the center of the absorbing atoms. The IFEFFIT (Demeter) software based set of EXAFS data analysis program has been used for generating the theoretical EXAFS spectra, shown in Figure (starting from an assumed crystallographic structure), and best fitting parameters …”

Section: Resultsmentioning

confidence: 99%

Selective Liquid‐Liquid Extraction of Uranium by Phosphoramidate‐Group Bearing Ionic Liquid

et al. 2019

Self Cite

View full text Add to dashboard Cite

Extraction of pure uranium (U) from its ore or spent nuclear fuel and separation of U for trace impurities characterization of nuclear fuels are the processes resulting into the accumulation of large amounts of low boiling and volatile organic waste. The limited reusability and degradation (chemical and radiation induced) of these waste solutions turning out to be an environmental threat. The authors have addressed this issue by developing an eco-friendly, simple and selective liquid-liquid extraction (LLE) procedure for U employing a phosphoramidate group bearing task specific ionic liquid (TSIL). Optimization of various LLE parameters resulted in high distribution ratio (D) value of 174 � 5 for U when extracted from 5 mol L À 1 HNO 3 medium. A detailed study on the infrared and extended X-ray absorption fine structure spectroscopy of U loaded ionic liquid phase reveals the extraction mechanism. Such high D U value resulted in high separation factors for U with respect to the elements which are commonly present in the ore, processed nuclear fuel and spent nuclear fuel. The structural integrity and metal ion extractability of the TSIL is found to remain unaffected when irradiated up to an absorbed dose of 400 kilogray (kGy). Sodium carbonate solution is found to backextract � 95% of U from the ionic liquid phase and regenerate it for further usage.persuing research in this field and we are further working on these directions. Supporting Information SummaryAll the information regarding instruments, optimized instrumental parameters, reagents, solutions and the extraction procedure have been provided in supporting information.

show abstract

Structural Investigations of (Ni,Cu) Co–Doped ZnO Nanocrystals by X‐ray Absorption Spectroscopy

Cited by 5 publications

References 44 publications

Bioinspired Cu(II) Defect Sites in ZIF-8 for Selective Methane Oxidation

Bioinspired Cu(II) Defect Sites in ZIF-8 for Selective Methane Oxidation

Plasmonic Ag nanoparticles arbitrated enhanced photodetection in p-NiO/n-rGO heterojunction for future self-powered UV photodetectors

Selective Liquid‐Liquid Extraction of Uranium by Phosphoramidate‐Group Bearing Ionic Liquid

Contact Info

Product

Resources

About