排序方式: 共有14条查询结果,搜索用时 15 毫秒
1.
P. Sreekumari Nair T. Radhakrishnan N. Revaprasadu A.S. Luyt 《Journal of Physics and Chemistry of Solids》2005,66(7):1302-1306
Composites of CdS nanoparticles confined in a polystyrene-co-maleic acid (PS-co-MAc) matrix have been prepared and characterized. It was shown that the acid groups of the co-polymer could be successfully used to control the aggregation of the nanoparticles, because they act as coordinate sites for Cd ions. UV-VIS measurements showed a blue shift of the absorption threshold, proving the presence of nanoparticles. An average size of the nanoparticles of about 4 nm is estimated from the change in band gap energy. Although the FTIR spectrum of the nanocomposite showed the presence of C-S bonds, a broad emission originating from surface recombination sites are noticed. DSC and TGA measurements revealed changes in thermal properties upon incorporation of nanoparticles. No thermal transition was observed in the nanocomposite, while the pure co-polymer exhibits a glass transition at 190 °C. In the presence of nanoparticles the onset of the thermal decomposition of the matrix is also shifted by 50 °C towards a higher temperature. 相似文献
2.
The single X-ray structures of the thiosemicarbazide complexes [Cd(NH2CSNHNH2)Cl2]n·H2O (A) and [Cd(NH2CSNHNH2)2Cl2]n (B) are reported. Both compounds have been found to be effective as single source precursors for the preparation of CdS nanomaterials. Thermal decomposition of the precursors in hexadecylamine (HDA) results in the formation of nanorods of different dimensions. The powder X-ray diffraction patterns of the nanodimensional materials reveal differences in the phases of the CdS synthesized from the two complexes. The particles synthesized from both precursors show quantum confinement effects in their absorption spectra, with the evidence of a broad defect emission in their photoluminescence spectra. 相似文献
3.
Nair PS Radhakrishnan T Revaprasadu N Kolawole GA O'Brien P 《Chemical communications (Cambridge, England)》2002,(6):564-565
We report the preparation of CdS nanorods using a thiosemicarbazide complex of cadmium [Cd(NH2CSNHNH2)2Cl2]. The precursor was decomposed in tri-n-octylphosphine oxide (TOPO) at 280 degrees C to give TOPO capped CdS nanoparticles; nano-dimensional rods of the material are clearly visible in transmission electron microscopy (TEM); the particles have been further characterised by X-ray diffraction (XRD) and selected area electron diffraction (SAED) and optical measurements. 相似文献
4.
Kevin I. Y. KETCHEMEN Sixberth MLOWE Linda D. NYAMEN Peter T. NDIFON Neerish REVAPRASADU 《Turkish Journal of Chemistry》2021,45(2):400
Cadmium dithiocarbamate and cadmium ethyl xanthate complexes were synthesized and characterized by microanalysis, Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analyses. The complexes were employed as molecular precursors for the fabrication of CdS nanoparticles in hexadecylamine (HDA) and oleylamine (OLA) at a temperature of 250 °C. Spherical and oval shaped particles with sizes ranging from 9.93 ± 1.89 to 16.74 ± 2.78 nm were obtained in OLA while spherical, oval and rod shaped particles with sizes ranging from 9.40 ± 1.65 to 29.90 ± 5.32 nm were obtained in HDA. Optical properties of the nanoparticles showed blue shifts as compared to the bulk CdS, with the OLA capped nanoparticles slightly more blue shifted than the corresponding HDA capped nanoparticles. Results of crystallinity patterns revealed hexagonal phase of CdS. 相似文献
5.
Thandeka Mthethwa V.S.R. Rajasekhar Pullabhotla Phumlani S. Mdluli James Wesley-Smith Neerish Revaprasadu 《Polyhedron》2009,28(14):2977-2982
Heterocyclic cadmium dithiocarbamates, [Cd(S2CNC5H10)2] and [Cd(S2CNC9H10)2] were synthesized. The complexes were thermolysed in hexadecylamine (HDA) to give HDA capped CdS nanoparticles. A combination of close to spherical, rod, bipods and tripods was obtained by varying the reaction parameters such as precursor concentration and temperature. The optical properties and X-ray diffraction studies of the particles are also reported. 相似文献
6.
Dr. Gwaza E. Ayom Dr. Malik D. Khan Tenzin Ingsel Wang Lin Dr. Ram K. Gupta Sizwe J. Zamisa Prof. Werner E. van Zyl Prof. Neerish Revaprasadu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2693-2704
Herein, the synthesis of three nickel(II) dithiophosphonate complexes of the type [Ni{S2P(OR)(4-C6H4OMe)}2] [R=H ( 1 ), C3H7 ( 2 )] and [Ni{S2P(OR)(4-C6H4OEt}2] [R=(C6H5)2CH ( 3 )] is described; their structures were confirmed by single-crystal X-ray studies. These complexes were subjected to surfactant/solvent reactions at 300 °C for one hour as flexible molecular precursors to prepare either nickel sulfide or nickel phosphide particles. The decomposition of complex 2 in tri-octylphosphine oxide/1-octadecene (TOPO/ODE), TOPO/tri-n-octylphosphine (TOP), hexadecylamine (HDA)/TOP, and HDA/ODE yielded hexagonal NiS, Ni2P, Ni5P4, and rhombohedral NiS, respectively. Similarly, the decomposition of complex 1 in TOPO/TOP and HDA/TOP yielded hexagonal Ni2P and Ni5P4, respectively, and that of complex 3 in similar solvents led to hexagonal Ni5P4, with TOP as the likely phosphorus provider. Hexagonal NiS was prepared from the solvent-less decomposition of complexes 1 and 2 at 400 °C. NiS (rhom) had the best specific supercapacitance of 2304 F g−1 at a scan rate of 2 mV s−1 followed by 1672 F g−1 of Ni2P (hex). Similarly, NiS (rhom) and Ni2P (hex) showed the highest power and energy densities of 7.4 kW kg−1 and 54.16 W kg−1 as well as 6.3 kW kg−1 and 44.7 W kg−1, respectively. Ni5P4 (hex) had the lowest recorded overpotential of 350 mV at a current density of 50 mA cm−2 among the samples tested for the oxygen evolution reaction (OER). NiS (hex) and Ni5P4 (hex) had the lowest overpotentials of 231 and 235 mV to achieve a current density of 50 mA cm−2, respectively, in hydrogen evolution reaction (HER) examinations. 相似文献
7.
Nyamen LD Rajasekhar Pullabhotla VS Nejo AA Ndifon PT Warner JH Revaprasadu N 《Dalton transactions (Cambridge, England : 2003)》2012,41(27):8297-8302
We report the synthesis of lead piperidine and lead tetrahydroquinoline dithiocarbamate (DTC) complexes and their use as single source precursors for the preparation of anisotropic PbS nanoparticles. The complexes were thermolysed in coordinating solvents such hexadecylamime (HDA), tri-n-octylphosphine oxide (TOPO), oleylamine (OA) and decylamine (DA) at various reaction temperatures. The variation of the reaction conditions and precursors produced PbS particles with shapes ranging from spheres to cubes and rods. The size of the particles is generally larger than those synthesized by conventional precursor routes. The electron microscopy and X-ray diffraction data confirm the particles to be very crystalline with the dominant cubic rock salt phase present in all samples. 相似文献
8.
Heterocyclic Bismuth(III) Dithiocarbamato Complexes as Single‐Source Precursors for the Synthesis of Anisotropic Bi2S3 Nanoparticles
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Walter N. Kun Dr. Sixberth Mlowe Dr. Linda D. Nyamen Prof. Peter T. Ndifon Dr. Mohammad A. Malik Prof. Orde Q. Munro Prof. Neerish Revaprasadu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13127-13135
New complexes catena‐(μ2‐nitrato‐O,O′)bis(piperidinedithiocarbamato)bismuth(III) ( 1 ) and tetrakis(μ‐nitrato)tetrakis[bis(tetrahydroquinolinedithiocarbamato)bismuth(III)] ( 2 ) were synthesised and characterised by elemental analysis, FTIR spectroscopy and thermogravimetric analysis. The single‐crystal X‐ray structures of 1 and 2 were determined. The coordination numbers of the BiIII ion are 8 for 1 and ≥6 for 2 when the experimental electron density for the nominal 6s2 lone pair of electrons is included. Both complexes were used as single‐source precursors for the synthesis of dodecylamine‐, hexadecylamine‐, oleylamine and tri‐n‐octylphosphine oxide‐capped Bi2S3 nanoparticles at different temperatures. UV/Vis spectra showed a blueshift in the absorbance band edge characteristic of a quantum size effect. High‐quality, crystalline, long and short Bi2S3 nanorods were obtained depending on the thermolysis temperature, which was varied from 190 to 270 °C. A general trend of increasing particle breadth with increasing reaction temperature and increasing length of the carbon chain of the amine (capping agent) was observed. Powder XRD patterns revealed the orthorhombic crystal structure of Bi2S3. 相似文献
9.
Crystals of the cadmium(II) complexes of N,N-diisopropylthiourea and N,N-dicyclohexylthiourea were obtained and their X-ray single crystal structures determined. These complexes are air-stable, easy to prepare and inexpensive and decompose cleanly to give good quality crystalline CdS. The nanoparticles of CdS thus obtained showed quantum confinement effects in their optical spectra, with close to band-edge emission in luminescence experiments. The broad diffraction patterns observed are typical of nanodimensional particles. The variation of concentration of precursor-to-HDA ratio change the isolated materials from spheres to rod-shaped. TEM images showed agglomerates of needle-like plate of particles. 相似文献
10.
Syabonga G. Sibiya Dr. Gwaza E. Ayom Dr. Malik D. Khan Dr. Jonghyun Choi Dr. Sanket Bhoyate Prof. Ram K. Gupta Prof. Neerish Revaprasadu 《欧洲无机化学杂志》2023,26(18):e202300087
The synthesis of solvent-less bare-surface nickel phosphides is desired, considering their superior electrocatalytic properties and straightforward synthetic protocols compared to their analogues prepared from colloidal routes. Herein, we report the synthesis of [Ni{S2P(OH)(4-CH3OC6H4)}2] (1), [Fe{S2P(OH)(4-CH3OC6H4)}3] (2) and [Co{S2P(OC4H9)(4-CH3OC6H4)}3] (3) and their utilization to form Ni2P, Fe-Ni2P and Co-Ni2P in a solvent-less pyrolysis method. This solvent-free protocol involved the decomposition of complex ( 1 ) and the composites of complex ( 1 ) with ( 2 ) or ( 3 ) in the presence of triphenylphosphine (TPP) at 400 °C for one hour. The solvent-less decomposition of complex ( 1 ) without TPP formed nickel sulfide. A plausible explanation for this rare fabrication of pristine and doped Ni2P in the absence of any solvent is suggested. All the transition metal doped phosphides improved the HER performance of pristine Ni2P, with the 5 % Fe doped Ni2P having the best performance, requiring 137 mV to reach a current density of 10 mA/cm2. Similarly, the OER performance of un-doped Ni2P was improved by all the doped Ni2P catalysts, where 10 % Fe-doped Ni2P showed the best performance requiring 326 mV to reach a current density of 10 mA/cm2. Transition metal doping was also shown to improve the reaction kinetics, stability and durability of the solvent-free prepared Ni2P. 相似文献