@article {43899, title = {Copper Cobalt Sulfide Nanosheets Realizing a Promising Electrocatalytic Oxygen Evolution Reaction}, journal = {ACS Catalysis}, volume = {7}, year = {2017}, month = {SEP}, chapter = {5871-5879}, abstract = {

Nanostructured CuCo2S4, a mixed metal thiospinel, is found to be a benchmark electrocatalyst for oxygen evolution reaction (OER) in this study with a low overpotential, a low Tafel slope, a high durability, and a high turnover frequency (TOF) at lower mass loadings. Nanosheets of CuCo2S4 are realized from a hydrothermal synthesis method in which the average thickness of the sheets is found to be in the range of 815 nm. Aggregated nanosheets form a highly open hierarchical structure. When used as an electrocatalyst, CuCo2S4 nanosheets offer an overpotential value of 310 mV at a 10 mA cm(2) current density, which remains consistent for 10000 measured cycles in a 1 M KOH electrolyte. A chronoamperometric study reveals constant oxygen evolution for 12 h at a 10 mV s(-1) scan rate without any degradation of the activity. Furthermore, the calculated mass activity of the CuCo2S4 electrocatalyst is found to be 14.29 A/g and to afford a TOF value of 0.1431 s(-1) at 310 mV at a mass loading of 0.7 mg cm(-2). For comparison, nanostructures of Co3S4 and Cu0.5Co2.5S4 have been synthesized using a similar method followed for CuCo2S4. When compared to the OER activities among these three thiospinels and standard IrO2, CuCo2S4 nanosheets offered the highest OER activities at the same mass loading (0.7 mg/cm(-2)). Extensive X-ray photoelectron spectroscopy and electron paramagnetic resonance analyses for a mechanistic study reveal that introduction of Cu into the Co3S4 lattice enhances the oxygen evolution and kinetics by offering Cu2+ sites for utilitarian adsorption of OH, O, and OOH reactive species and also by offering a highly active high-spin state of octahedral Co3+ for OER catalysis.

}, keywords = {Bifunctional Electrocatalyst, Catalyst, Cuco2s4, Efficient Electrocatalyst, electrocatalyst, Electronic-structure, Nanoparticles, Nanosheet, oxide, oxygen evolution, performance, Recent Progress, Water oxidation, Water Splitting Hydrogen Evolution}, doi = { 10.1021/acscatal.7b01831}, author = {Chauhan, Meenakshi and Reddy, Kasala Prabhakar and Gopinath, Chinnakonda S. and Deka, Sasanka} } @article {43870, title = {NiZn double hydroxide nanosheet-anchored nitrogen-doped graphene enriched with the gamma-NiOOH phase as an activity modulated water oxidation electrocatalyst}, journal = {Nanoscale}, volume = {9}, year = {2017}, month = {SEP}, pages = {12590-12600}, type = {Journal Article}, chapter = {12590-12600}, abstract = {

Herein, we report a facile solvothermal process to synthesize an active electrocatalyst for the oxygen evolution reaction (OER) in an alkaline medium by anchoring nanosheets of a NiZn double hydroxide over nitrogen doped reduced graphene oxide after enriching the system with the γ-NiOOH phase. This catalyst possesses a thin, porous and open layered structure, which makes the system more efficient and accessible for a better electrochemical water oxidation reaction. Moreover, we experimentally demonstrated that incorporation of Zn via a single-step solvothermal method provides an easy approach to obtain plenty of exposed γ-NiOOH phases to make the system more viable for OER with a small overpotential of 290 mV at 10 mA cm-2 and a Tafel slope of 44 mV per decade. In addition to this, the oxophilic nature of Zn in the (Zn)Ni-LDH/N-rGO catalyst helps to improve the long-term stability of the whole system. The obtained results open up possibilities for the design of future robust OER electrocatalysts by the use of very cheap and abundant materials like Ni and Zn in place of expensive Ir and Ru in the present commercial electrocatalysts.

}, keywords = {catalysis, Efficient Electrocatalyst, kinetics, Metal, Nickel-Hydroxide, oxide, Oxygen Evolution Reaction, performance, XPS Spectra, zinc}, issn = {2040-3364}, doi = {10.1039/c7nr02225e}, author = {Nadeema, Ayasha and Dhavale, Vishal M. and Kurungot, Sreekumar} } @article {47681, title = {Magnetic and magnetoelastic properties of Ni-substituted cobalt ferrite}, journal = {IEEE Magnetics Letters}, volume = {12}, year = {2021}, month = {JAN}, pages = {2504205}, type = {Article}, abstract = {In this letter, magnetic and magnetostriction studies were performed on spinel ferrite Co1-xNixFe2O4 (CNF series) with 0.0 < x < 0.5. All the samples were synthesized by the conventional ceramic method and confirmed to be forming pure spinel phase. The unit cell parameter showed gradual decrease with increasing Ni content. A linear decrease in saturation magnetization (M-s) and coercivity (H-c) was observed with increasing Ni substitution, which could be attributed to reduced magneto-crystalline anisotropy. The room temperature magnetostriction studies revealed a slow decrease in maximum magnetostriction, and interestingly, for 20\% reduction of cobalt concentration, i.e., for x = 0.2, a magnetostrictive strain of -164 ppm and substantially high stress sensitivity of -56 x 10(-6) A(-1) m were observed, making Co0.8Ni0.2Fe2O4 suitable for application as a magnetostrictive stress-sensing material.}, keywords = {Ferrite, Magnetism in solids, Magnetostriction, oxide, stress sensing}, issn = {1949-307X}, doi = {10.1109/LMAG.2021.3120942}, author = {Bhame, Shekhar D. and Shirolkar, Mandar M. and Joy, Pattayil A.} } @article {47895, title = {Catalytic activity of CuFe2O4 spinel oxide for liquid-phase oxidation of cinnamyl alcohol}, journal = {ChemistrySelect}, volume = {7}, year = {2022}, month = {FEB}, pages = {e202104441}, type = {Article}, abstract = {

CuFe2O4 spinel oxide catalyst was synthesized by sol-gel and co-precipitation methods for liquid phase oxidation of Cinnamyl alcohol (CnOH) to Cinnamaldehydes (CnHO) using tert-Butyl hydroperoxide (TBHP) as oxidising agent. Spinel oxide catalyst was characterized by different techniques such as X-ray diffraction (XRD), N-2 adsorption-desorption, BET surface area, and X-ray photoelectron spectroscopy (XPS) to understand the structural, physical properties and oxidation state of the catalyst. The result shows that catalyst prepared by sol-gel method was found higher surface area and smaller crystalline size than co-precipitation method. XPS data confirm the formation of Cu2+ in the spinel which helps to improve the catalytic activity of oxidation. This reaction follows radical mechanism, and exhibited 76.7 \% of CnOH conversion and 68.4 \% of CnHO, and 24.8 \% benzaldehyde (benzald) selectivity using TBHP at 60 degrees C. Kinetic data reveal that 41.2 kJ/mol of activation energy for the reaction. The higher activity of spinel oxide catalyst could be due synergetic effect of spinel (88 \%) and oxides (12 \%) formed in the catalyst, which helps to provide the oxygen during reaction. The contribution of Cu2+ is higher in sol-gel than co-precipitation, which may provide the better reactivity of catalyst. This work helps to select the effective and cost-effective catalyst for the oxidation of CnOH.

}, keywords = {Catalysts, Cinnamaldehyde, Cinnamyl Alcohol, Cupper, iron, oxide, spinel}, issn = {2365-6549}, doi = {10.1002/slct.202104441}, author = {Dange, Rutvija M. and Niphadkar, Prashant S. and Bokade, Vijay V. and Nandanwar, Sachin U.} } @article {48085, title = {Magnetostriction studies on transition metal substituted cobalt ferrite}, journal = {Journal of the Indian Chemical Society}, volume = {99}, year = {2022}, month = {AUG}, pages = {100599}, type = {Article}, abstract = {

Structural, magnetic and microstructural properties of transition metal (TM) substituted cobalt ferrite Co0.9TM0.1Fe2O4 (where TM = Ti, Cr, Mn, Ni and Cu and Zn) were investigated. The present study shows marked dependence of the magnetostriction on the concentration of the substituted transition metal ions for Cobalt in CoFe2O4. The magnetic characteristics of the prepared compositions such as coercivity, anisotropy constant and saturation magnetization changed significantly on transition metal substitution. The present study shows the way to tune the anisotropy of cobalt ferrite by effective substitution of other transition metal ions for Co which subsequently affects the stress sensing performance by changing the slope of the magnetostriction curve. Apart from the magnetic properties the microstructure can also be effectively modified by substitution of other transition metal ions. Only 10\% substitution of cobalt showed drastic influence on magnetostriction and slope of magnetostriction curve. The composition with 10\% nickel Co0.9Ni0.1Fe2O4 exhibited maximum slope for the magnetostriction curve of -53.7 ppm/Oe, along with reasonably high magnitude of strain of 186 ppm making it a suitable for exploring stress sensing applications.

}, keywords = {Ferrite, Magnetoelastic, Magnetostriction, oxide, stress sensing}, issn = {0019-4522}, doi = {10.1016/j.jics.2022.100599}, author = {Bhame, D. Shekhar and Bhapkar, Abhishek and Shirolkar, Mandar M. and Joy, Pattayil A.} }