Unique visible-light-assisted field emission of tetrapod-shaped ZnO/reduced graphene-oxide core/coating nanocomposites

Abstract

The electronic and the optoelectronic properties of graphene-based nanocomposites are controllable, making them promising for applications in diverse electronic devices. In this work, tetrapod-shaped zinc oxide (T-ZnO)/reduced graphene oxide (rGO) core/coating nanocomposites were synthesized by using a hydrothermal-assisted self-assemble method, and their optical, photoelectric, and field-emission properties were investigated. The ZnO, an ideal ultraviolet-light-sensitive semiconductor, was observed to have high sensitivity to visible light due to the rGO coating, and the mechanism of that sensitivity was investigated. We demonstrated for the first time that the field-emission properties of the T-ZnO/rGO core/coating nanocomposites could be dramatically enhanced under visible light by decreasing the turn-on field from 1.54 to 1.41 V/μm and by increasing the current density from 5 to 12 mA/cm2 at an electric field of 3.5 V/μm. The visible-light excitation induces an electron jump from oxygen vacancies on the surface of ZnO to the rGO layer, resulting in a decrease in the work function of the rGO and an increase in the emission current. Furthermore, a field-emission light-emitting diode with a self-enhanced effect was fabricated making full use of the photo-assisted field-emission process.

Synthesis, Characterization, and Photocatalytic Performance of ZnO–Graphene Nanocomposites: A Review

“…A great diversity of ZnO shapes has been reported in ZnO-graphene nanocomposites, as seen in Figure 15. The main ZnO morphologies are spheres (solid and hollow) [101], rods [102], flowers [103], core-shell [104], flakes [104], oval [105], wires [105], grains [106], cubes [107], quantum dots [108], trapezoids [109], tetrapods [110], and dumbbell [111]. The main problem in synthesizing this type of nanocomposites is the almost null control over ZnO's morphology.…”

Transparent conductive oxide type materials as the anode of solid oxide fuel cells at a reduced temperature

“…4) was used to analyze the superficial properties of ZGO before and after the treatment in 5% H 2 at 800 °C. The core-level scan of O 1s showed two peaks at 530.5 eV and 532 eV, which could be assigned to the lattice oxygen 42 and the presence of weak oxygen species or chemically adsorbed oxygen, 43,44 respectively, while the actual binding energy difference (Δ E ) between the Zn 2p 3/2 and Ga 2p 3/2 peaks were all about 96 eV, which was in line with the spinel. 45 Reduction in 5% H 2 induced a decrease in the binding energy for the Zn 2p and Ga 2p orbitals (Fig.…”

Proposed Industrial Scale Setup for Production of ZnO Nanoparticles Using Wet Chemical Synthesis Method

“…3(c). This suggests that oxygen is present in the crystalline ZnO nanoparticles and can be indexed to the O2-in the ZnO [18]. For the production of ZnO NPs on large scale, proposed industrial process design for the information obtained from as-synthesized ZnO NPs on laboratory scale.…”