@article {44433, title = {VSe2-reduced graphene oxide as efficient cathode material for field emission}, journal = {Journal of Physics and Chemistry of Solids }, volume = {128}, year = {2019}, month = {MAY}, pages = {384-390}, type = {Journal Article}, abstract = {

Field emission properties of pristine VSe2 and its hybrid with reduced graphene oxide (RGO) have been investigated in detail. Promising field emission performance were noted with lower values of turn-on and threshold fields of \~{}1.3 V μm-1 and 2.12 V μm-1 respectively for the VSe2/RGO hybrid which is much more superior than that of pristine VSe2 emitter and other 2D materials. Density Functional Theory (DFT) simulations have also been performed to qualitatively support our experimental observations through demonstration of Density of States and computation of work function for pristine VSe2 and hybrid VSe2/RGO. The lowering of work function and appearance of additional states near Fermi level from carbon p orbital of RGO is responsible for superior field emission characteristics in hybrid VSe2/RGO compared to pristine VSe2 which supports our experimental observations. Our experimental data and theoretical insight from electronic structure simulations strongly infer that the synthesized hybrid VSe2/RGO has the potential to be tailored as efficient and high performance cathode material in field emission based devices.

}, keywords = {cathode material, Chalcogenide, Density functional theory, field emission, Vanadium diselenide, Work function}, issn = {223697}, doi = {10.1016/j.jpcs.2018.02.020}, author = {Ratha, S.}, editor = {Bankar, P.} } @article {48000, title = {Sustainable CO2 reduction on in (2)O(3 )with exclusive CO selectivity: catalysis and in situ valence band photoelectron spectral investigations}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {10}, year = {2022}, month = {MAR}, pages = {3521-3531}, type = {Article}, abstract = {

This study demonstrates a sustainable catalytic CO2 conversion to near 100\% CO selectivity at ambient pressure on In2O3. Critically, high CO yield could be observed at the cost of undesired methanation, using a lower than stoichiometric amount of hydrogen in the feed; 1:1 and 1:0.67 CO2:H-2 ratios exhibit 98-99.6\% CO selectivity with 25-38\% CO2 conversion between 773 and 873 K. CO2 and H-2 conversion under steady-state conditions at 773-873 K suggests a 1:1 ratio of adsorbed reactants (with 1:0.67 CO2:H-2 feed) on the catalyst surface, underscoring the presence of an ideal reactant composition for the reverse water-gas shift reaction, while H-2-rich feed compositions show the H-2-dominated surface. Surface electronic structure changes, under near-operating conditions, were explored with near ambient pressure photoelectron spectroscopy (NAPPES), and the interesting findings are as follows: (a) A shift in the valence band to lower binding energy, up to 0.6 eV, was observed because of electron filling at high temperatures. (b) An observation of heterogeneous nature of the catalyst surface under NAPPES measurement conditions is attributed to the generation of active oxygen vacancy (O-v) sites, which in turn changes the work function of In2O3. (c) The above changes are found to be reversible, when the reaction was stopped. Vibrational features of the reactant molecules were observed to be broadened in the active temperature window of the catalyst supporting the heterogeneous character of the catalyst surface because of dynamic O-v generation. By optimizing gas hourly space velocity, CO2:H-2 ratio, and reaction temperature, exclusive CO selectivity is possible with a H-2:CO2 ratio of similar to 0.67, which will avoid the product separation stage altogether, while minimizing the expensive H-2 in the reactant feed.

}, keywords = {heterogeneous catalysis, Oxygen vacancy, photoelectron spectroscopy, RWGS, Work function}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.1c07897}, author = {Mhamane, Nitin B. and Chetry, Sibo and Ranjan, Ravi and Raja, Thirumalaiswamy and Gopinath, Chinnakonda S.} } @article {48047, title = {Tuning of work function of ZnO by doping and co-doping: an investigation using X-ray photoelectron spectroscopy}, journal = {Thin Solid Films}, volume = {761}, year = {2022}, month = {NOV}, pages = {139538}, type = {Article}, abstract = {

The shift in the work function of the ZnO thin film upon varying codoping ratio has been investigated by X-ray photoelectron spectroscopy. A notable shift of 0.2 eV in the work function was achieved in the films when the Al: In doping ratio was changed from 0:10 to 10:0. The elemental composition of the dopants obtained from XPS analysis showed the presence of more amount of In dopant than Al in codoped ZnO films. In this way a clear understanding of the variation in electrical properties on dopant ratio is obtained. A decrease in work function was also observed with the increase in free carrier concentration when the codopant ratio is changed. The effects of Burstein moss, band narrowing, and band renormalization observed in the bandgap were explained by an upward and downward shift of valence band maxima of the corresponding thin films. The controllable work function of the codoped ZnO films by varying the doping ratio offers excellent potential advantages in optoelectronic devices.

}, keywords = {Indium -Aluminum co -doping, Spray coating, thin film, Work function, X-ray photoelectron spectroscopy, Zinc oxide}, issn = {0040-6090}, doi = {10.1016/j.tsf.2022.139538}, author = {Soumya, K. and Selvam, I. Packia and Vinod, C. P. and Potty, S. N.} }