We report here the field emission studies of a layered WS2-RGO composite at the base pressure of ~1 × 10−8 mbar. The turn on field required to draw a field emission current density of 1 μA/cm2 is found to be 3.5, 2.3 and 2 V/μm for WS2, RGO and the WS2-RGO composite respectively. The enhanced field emission behavior observed for the WS2-RGO nanocomposite is attributed to a high field enhancement factor of 2978, which is associated with the surface protrusions of the single-to-few layer thick sheets of the nanocomposite. The highest current density of ~800 μA/cm2 is drawn at an applied field of 4.1 V/μm from a few layers of the WS2-RGO nanocomposite. Furthermore, first-principles density functional calculations suggest that the enhanced field emission may also be due to an overalp of the electronic structures of WS2 and RGO, where graphene-like states are dumped in the region of the WS2 fundamental gap.

We report here our experimental investigations on p-doped graphene using tin sulfide (SnS2), which shows enhanced field emission properties. The turn on field required to draw an emission current density of 1 μA/cm2 is significantly low (almost half the value) for the SnS2/reduced graphene oxide (RGO) nanocomposite (2.65 V/μm) compared to pristine SnS2 (4.8 V/μm) nanosheets. The field enhancement factor β (∼3200 for the SnS2 and ∼3700 for SnS2/RGO composite) was calculated from Fowler-Nordheim (F-N) plots, which indicates that the emission is from the nanometric geometry of the emitter. The field emission current versus time plot shows overall good emission stability for the SnS2/RGO emitter. The magnitude of work function of SnS2 and a SnS2/graphene composite has been calculated from first principles density functional theory (DFT) and is found to be 6.89 eV and 5.42 eV, respectively. The DFT calculations clearly reveal that the enhanced field emission properties of SnS2/RGO are due to a substantial lowering of the work function of SnS2 when supported by graphene, which is in response to p-type doping of graphene.

SnS2 nanosheets (SnS2NSs), synthesized by one-step hydrothermal reaction, are subjected to field emission (FE) studies. For synthesis, specific concentrations of Na2SnO3 and thioamide solutions are used. The FE study is carried out in a planar diode configuration at a base pressure of ∼10−8 mbar. The emission photosensitivity is also investigated by illuminating the specimen with a visible light source. In dark, the turn on field, the electric field required to obtain a current density of 1 μA/cm2, is found to be 5.9 V/μm. Upon illumination, the emitter with visible light, it is found to reduce to 5.0 V/μm. A significant change in the nature of the Fowler–Nordheim plot with light illumination is also observed and has been explained on the basis of photoconductivity. Repetitive switching ON and OFF the light source, at a fixed applied voltage, is found to generate current pulses. The photosensitivity is also studied with various color filters. With the photoswitching and the enhanced field emission properties, it is envisaged that SnS2NSs possess a potential for optoelectronic applications of field emitters.

SnSz nanosheets (SnSzNSs), synthesized by one-step hydrothermal reaction, are subjected to Field Emission (FE)studies. For synthesis, specific concentrations of NaZSn03 and thioamide solution are used. The FE study is carried out in all metal Ultra High Vacuum (UHV) chamber in planar diode configuration at a base pressure of -10-8 torr. A maximum current density of 110 /-lA/cm z was attainable. The turn on field required to draw a current density of 1 /-lA/cm z is found to be 2.6

a b s t r a c tAntioxidant activity of decoctions and fresh juice samples of raw fruit parts of Lagenaria siceraria (Mol.) Standely, (L.S.), viz., fruit pulp, whole fruit and fruit skin, has been evaluated in terms of radical scavenging ability by pulse radiolysis method and phenolic content by FolineCiocalteu assay. The decay of ABTS À radical anion generated by pulse radiolysis has been monitored in presence of samples. The trend in the radical scavenging ability of six samples recorded in terms of ascorbic acid equivalent (AAE) values (4.650e41.230 AAE mg/g fresh weight) have been found to correlate well with the trends in phenolic content of these samples expressed as gallic acid equivalent (GAE) values (0.417e2.000 GAE mg/g fresh weight). The result also shows that the antioxidant activity of decoctions of all the three fruit parts is higher, apparent from their higher AAE and GAE values than the corresponding fresh juice samples.