A Review of Graphene Oxide Crosslinking as Enhanced Corrosion Shield Application

Nowadays,corrosion is not only undesirable,but it also has a significant influence on the industrial sectors and technical innovations that have demand for metals.The global economic damage is expected to reach$2.5 trillion,equivalent to more than 3.4%of the world’s GDP in 2013.It is linked with significant financial harm,manufacturing pollution,and safety issues.An electrochemical process primarily induces metal corrosion at the metalelectrolyte interface region,caused by steel oxidation and the reduction of oxygen,protons,and water.Therefore,organic and epoxy coatings can be applied as protective coatings.Additionally,it can prevent metal corrosion in various fields due to its unique properties,like the ability to manage its curing process over a long period.This review paper focuses on improving the physicomechanical properties of modified graphene oxide(GO)coating by attaching a polymer,epoxy resin(EP).Moreover,we reviewed recent achievements for different methods in minimizing a corrosion phenomenon.Further,we considered the modification of epoxy resin using the curing agent as a bridge to the polymer to strengthen the functionalization of nanocomposites during the reaction.Afterward,we discussed the relationship between the modified GO/EP anticorrosive coating and physicomechanical properties since it is currently being questioned and remains unresolved.As a result,extensive studies on the mechanism of synthesis of the modified GO/EP anticorrosive coating were highlighted.

Applied bias photon-to-current conversion efficiency of ZnO enhanced by hybridization with reduced graphene oxide

The role of reduced graphene oxide（rGO） in the enhancement of photo-conversion efficiency of ZnO films for photoelectrochemical（PEC） water-splitting applications was analyzed. ZnO and rGO-hybridized ZnO（rGO/ZnO） films were prepared via a two-step electrochemical deposition method followed by annealing at 300 °C under argon gas flow. The physical, optical and electrochemical properties of the films were characterized to identify the effect of rGO-hybridization on the applied bias photon-to-current efficiency（ABPE） of ZnO. Scanning electron microscopy and X-ray diffraction indicated the formation of verticallyaligned, wurtzite-phase ZnO nanorods. Diffuse-reflectance UV–visible spectroscopy indicated that rGO-hybridization was able to increase the light absorption range of the rGO/ZnO film. UPS analysis showed that hybridization with rGO increased the band gap of ZnO（3.56 eV） to 3.63 eV for rGO/ZnO sample,which may be attributed to the Burstein–Moss effect. Photoluminescence（PL） spectra disclosed that rGOhybridization suppressed electron-hole recombination due to crystal defects. Linear sweep voltammetry of the prepared thin films showed photocurrent density of 1.0 and 1.8 m A/cm;for ZnO and rGO/ZnO at+0.7 V, which corresponded to an ABPE of 0.55% and 0.95%, respectively. Thus, this report highlighted the multi-faceted role of rGO-hybridization in the enhancement of ZnO photo-conversion efficiency.

Novel layer-by-layer assembly of rGO-hybridised ZnO sandwich thin films for the improvement of photo-catalysed hydrogen production

Metal oxide semiconductor materials such as ZnO have tremendous potential as light absorbers for photocatalysed electrodes in the electrochemical reduction of water. Promoters such as rGO have been added to reduce the recombination losses of charge carriers and improve its photoelectrochemical activity. In this study, the effect of layer ordering on the charge transfer properties of rGO-hybridised ZnO sandwich thin films for the photo-catalysed electrochemical reduction of water was investigated. rGO-hybridised ZnO sandwich thin films were prepared via a facile electrode position technique using a layer-by-layer approach. The thin films were analysed using FESEM, XRD, Raman, PL, UV–vis, EIS and CV techniques to investigate its morphological, optical and electrochemical properties. The FESEM images show the formation of distinct layers of rGO and ZnO nanorods/flakes via the layer-by-layer method. XRD confirmed the wurtzite structure of ZnO. PL spectroscopy revealed a reduction of photoemission intensity in the visible region（580 nm） when rGO was incorporated into the ZnO thin film. Among the six thin films prepared, ZnO/rGO showed superior performance compared to the other thin films（0.964 m A/cm） due to the presence of graphene edges which participate as heterogenous electrocatalysts in the photocatalysed electrolysis of water. rGO also acts as electron acceptor, forming an n-p heterojunction which improves the activity of ZnO to oxidise water molecules to O2. EIS revealed that the application of rGO as back contact（rGO/ZnO, rGO/ZnO/rGO） reduces the charge transfer resistance of a semiconductor thin film. Alternatively, rGO as front contact（ZnO/rGO, rGO/ZnO/rGO） improves the photo-catalysed electrolysis of water through the participation of the rGO edges in the chemical activation of water. The findings from this study indicate that the layer ordering significantly affects the thin film＇s electrostatic properties and this understanding can be further advantageous for tunable applications.

Enhance of TiO_2 dopants incorporated reduced graphene oxide via RF magnetron sputtering for efficient dye-sensitised solar cells

In particular, the dye-sensitised solar cells(DSSCs) have a high potential in the rational energy conversion efficiency to secure our sustainable energy source.In the present study, advanced radio frequency(RF) magnetron sputtering technique was applied to incorporate titanium dioxide(TiO) dopants into reduced graphene oxide(rGO) nanosheet for improving the power conversion efficiency(PCE) of DSSCs device. An optimum TiOcontent incorporated onto rGO nanosheet plays an important role in improving the PCE of DSSCs by minimising the recombination losses of photo-induced charge carriers.Based on the results obtained, 40-s sputtering duration for incorporating TiOdopants onto rGO nanosheet exhibits a maximum PCE of 8.78% than that of pure rGO film(0.68%). In fact, the presence of optimum content of TiOdopants within rGO nanosheet could act as mediators for efficient separation photo-induced charge carriers. However, the excessive of sputtering duration(e.g. 60 s) of TiOdopants onto rGO nanosheet results higher charge recombination and lowers the PCE of DSSCs(5.39%).