Surface‐enhanced Raman scattering characteristics of CuO : Mn/Ag heterojunction probed by methyl orange: effect of Mn<sup>2+</sup> doping

Prakash, Om; Kumar, Sanjay; Singh, Prabha; Deckert, Volker; Chatterjee, Sandip; Ghosh, Anup K.; Singh, Ranjan K.

doi:10.1002/jrs.4904

Cited by 49 publications

(20 citation statements)

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“…B. The sample CuO/γ‐Al 2 O 3 prepared by impregnation exhibits Raman bands at 280, 330, 612, and 1100 cm −1 , which agrees well with the monoclinic CuO nanoparticles . It is interesting to note that the cubic CuO nanoparticles prepared by CVD gives a group of completely different Raman peaks at 98, 148, 220, and 635 cm −1 compared with the monoclinic CuO prepared by impregnation.…”

Section: Resultssupporting

confidence: 62%

Phase‐controlled growth of cubic phase CuO nanoparticles by chemical vapor deposition

Shi

Liu

Chen

et al. 2017

Physica Status Solidi (a)

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Cupric oxide has three polymorphs, namely, monoclinic, tetragonal, and cubic phases. The synthesis of the monoclinic phase is widely reported due to its versatile applications. However, cupric oxides with tetragonal and cubic structures were seldom investigated in the literature. In this study, the cubic phase of CuO was deposited on alumina substrate using Cu(acac) 2 as precursor. The obtained CuO with loadings of 0.2-2 mmol g À1 on alumina was determined to be pure cubic phase by XRD and XPS, which is the first report on the synthesis of pure cubic phase, to the best of our knowledge. In contrast, pure monoclinic phase was obtained when impregnation method was employed. The cubic CuO nanoparticles obtained in this work appear to be highly dispersed with a particle size of around 5 nm. Moreover, the cubic CuO showed a lower chemical state and a lower reducibility as compared to monoclinic CuO supported on the same substrate. Further studies showed that the cubic phase was a metastable phase in thermodynamics and could be converted to monoclinic phase at elevated temperatures. As catalysts, the cubic CuO on alumina was found to be active and selective in the hydroxylation of phenol to catechol, hydroquinone and benzoquinone.

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Section: Resultssupporting

confidence: 62%

Phase‐controlled growth of cubic phase CuO nanoparticles by chemical vapor deposition

Shi

Liu

Chen

et al. 2017

Physica Status Solidi (a)

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“…This blue shifting of the major Raman bands of MO and CO in CMO@MCO can be ascribed to the local structure distortion of MO and CO induced by doping. 45 , 47 Besides, the intensity reduction with the broadening of the major peaks demonstrates the occurrence of lattice defects by the creation of oxygen vacancies. 45 These results further specify the formation of MO, CO, and CMO@MCO with good crystallinity, which is consistent with the XRD results.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Cu-Doped Mn₃O₄@Mn-Doped CuO Nanostructured Electrode Materials by a Solution Process for High-Performance Electrochemical Pseudocapacitors

et al. 2020

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Cu-doped Mn 3 O 4 and Mn-doped CuO (CMO@MCO) mixed oxides with isolated phases together with pristine Mn 3 O 4 (MO) and CuO (CO) have been synthesized by a simple solution process for applications in electrochemical supercapacitors. The crystallographic, spectroscopic, and morphological analyses revealed the formation of all of the materials with good crystallinity and purity with the creation of rhombohedral-shaped MO and CMO and a mixture of spherical and rod-shaped CO and MCO nanostructures. The ratio of CMO and MCO in the optimized CMO@MCO was 2:1 with the Cu and Mn dopants percentages of 12 and 15%, respectively. The MO-, CO-, and CMO@MCO-modified carbon cloth (CC) electrodes delivered the specific capacitance ( C s ) values of 541.1, 706.7, and 997.2 F/g at 5 mV/s and 413.4, 480.5, and 561.1 F/g at 1.3 A/g, respectively. This enhanced C s value of CMO@MCO with an energy density and a power density of 78.0 Wh/kg and 650.0 W/kg, respectively, could be attributed to the improvement of electrical conductivity induced by the dopants and the high percentage of oxygen vacancies. This corroborated to a decrease in the optical band gap and charge-transfer resistance ( R ct ) of CMO@MCO at the electrode/electrolyte interface compared to those of MO and CO. The net enhancement of the Faradaic contribution induced by the redox reaction of the dopant and improved surface area was also responsible for the better electrochemical performance of CMO@MCO. The CMO@MCO/CC electrode showed high electrochemical stability with a C s loss of only ca. 4.7%. This research could open up new possibilities for the development of doped mixed oxides for high-performance supercapacitors.

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“…The strongly localized character of the surface plasmon, i.e., its electric field E (r) SP scales with 1/r 3 , limits the probing area down to a few nanometers (d SP ≈ 4-5 nm) [38,39], making the study of the manganite surface by means of Raman spectroscopy in principle possible. However, up to now only a few studies were performed on oxides, mostly focused on nanoparticles rather than thin films [40][41][42]. Moreover, to the best of our knowledge, only one TERS study on a strongly correlated material, the double perovskite La 2 CoMnO 6 [43], was published, but no surface-oriented studies of the mixed-valence manganites, La 1−x A x MnO 3 , were reported up to now.…”

Section: Introductionmentioning

confidence: 99%

Jahn-Teller reconstructed surface of the doped manganites shown by means of surface-enhanced Raman spectroscopy

Merten

Bruchmann-Bamberg

Damaschke

et al. 2019

Phys. Rev. Materials

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We report direct evidence of the theoretically predicted electron-rich surface of doped perovskite manganites La 0.7 A 0.3 MnO 3 (A = Ca, Sr) by means of surface-enhanced Raman spectroscopy. The required Au nanoparticles were grown on top of thin manganite films by the metalorganic aerosol deposition technique, which provides a stable oxygen atmosphere and prevents deoxygenation effects. The acquired surface-enhanced Raman spectra of rhombohedral La 0.7 Sr 0.3 MnO 3 thin films reveal the symmetry-forbidden Jahn-Teller stretching modes demonstrating the predicted symmetry breaking at the surface and fallback into the orthorhombic (Pnma) structure. This results in a unique Jahn-Teller reconstructed surface structure, which limits the capabilities of mixed-valence manganites in spintronic applications, but will be highly favorable for catalytic reactions.

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Surface‐enhanced Raman scattering characteristics of CuO : Mn/Ag heterojunction probed by methyl orange: effect of Mn²⁺ doping

Cited by 49 publications

References 50 publications

Phase‐controlled growth of cubic phase CuO nanoparticles by chemical vapor deposition

Phase‐controlled growth of cubic phase CuO nanoparticles by chemical vapor deposition

Synthesis of Cu-Doped Mn₃O₄@Mn-Doped CuO Nanostructured Electrode Materials by a Solution Process for High-Performance Electrochemical Pseudocapacitors

Jahn-Teller reconstructed surface of the doped manganites shown by means of surface-enhanced Raman spectroscopy

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Surface‐enhanced Raman scattering characteristics of CuO : Mn/Ag heterojunction probed by methyl orange: effect of Mn2+ doping

Cited by 49 publications

References 50 publications

Phase‐controlled growth of cubic phase CuO nanoparticles by chemical vapor deposition

Phase‐controlled growth of cubic phase CuO nanoparticles by chemical vapor deposition

Synthesis of Cu-Doped Mn3O4@Mn-Doped CuO Nanostructured Electrode Materials by a Solution Process for High-Performance Electrochemical Pseudocapacitors

Jahn-Teller reconstructed surface of the doped manganites shown by means of surface-enhanced Raman spectroscopy

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Surface‐enhanced Raman scattering characteristics of CuO : Mn/Ag heterojunction probed by methyl orange: effect of Mn²⁺ doping

Synthesis of Cu-Doped Mn₃O₄@Mn-Doped CuO Nanostructured Electrode Materials by a Solution Process for High-Performance Electrochemical Pseudocapacitors