The significance of graphene and its two-dimensional (2D) analogous inorganic layered materials especially as hexagonal boron nitride (h-BN) and molybdenum disulphide (MoS2) for “clean energy” applications became apparent over the last few years due to their extraordinary properties. In this review article we study the current progress and selected challenges in the syntheses of graphene, h-BN and MoS2 including energy storage applications as supercapacitors and batteries. Various substrates/catalysts (metals/insulator/semiconducting) have been used to obtain graphene, h-BN and MoS2 using different kinds of precursors. The most widespread methods for synthesis of graphene, h-BN and MoS2 layers are chemical vapor deposition (CVD), plasma-enhanced CVD, hydro/solvothermal methods, liquid phase exfoliation, physical methods etc. Current research has shown that graphene, h-BN and MoS2 layered materials modified with metal oxide can have an insightful influence on the performance of energy storage devices as supercapacitors and batteries. This review article also contains the discussion on the opportunities and perspectives of these materials (graphene, h-BN and MoS2) in the energy storage fields. We expect that this written review article including recent research on energy storage will help in generating new insights for further development and practical applications of graphene, h-BN and MoS2 layers based materials.

A review on synthesis of graphene, h-BN and MoS 2 for energy storage applications: Recent progress and perspectives

We
report a low-cost and green synthesis approach to produce high-performance
optoelectronics based on WS2-decorated pencil trace on
ordinary cellulose paper It is noteworthy that the photodetector
was prepared via simply nontoxic solution-processed
WS2 nanosheets, pencil-drawn graphene conducting films,
and biodegradable papers Portable and flexible electronics based
on WS2/graphene show excellent photoresponse in a broad
spectral region from visible to near IR because of plasmonic improvement
and efficient photoabsorption Liquid-phase-exfoliated atomically
thin WS2 nanosheets were decorated on a conducting film
of pencil trace using the large area electrophoretic deposition technique
The photodetector based on the WS2/graphene heterostructure
shows excellent temporal photoresponse with a responsivity of 0439
A/W, a detectivity of 141 × 1010 Jones, and an external
quantum efficiency of 8139% The high-performance photodetector shows
piezoresistive modulation in electric transport The device response
was investigated up to 500 bending cycles Finally, the present finding
advocates the great development over previously reported nonbiodegradable
and small-area optoelectronic devices

WS2 Nanosheet/Graphene Heterostructures for Paper-Based Flexible Photodetectors

Synthesis of 3D-MoS2 nanoflowers with tunable surface area for the application in photocatalysis and SERS based sensing

Plasmonic improvement photoresponse of vertical-MoS2 nanostructure photodetector by Au nanoparticles

Exciton and trion in few-layer MoS2: Thickness- and temperature-dependent photoluminescence

Facile, scalable and transfer free vertical-MoS2 nanostructures grown on Au/SiO2 patterned electrode for photodetector application

The spin Hall effect is considered a phenomenon in which a charge current is converted to a spin current due to the spin-orbit coupling (SOC). Recently, large values of the spin Hall angle (SHA), as the conversion efficiency between spin and charge currents, were observed in metal oxide structures in ferromagnetic/metal (FM/M) oxide bilayers, although their underlying mechanisms are ambiguous. The present study aims to analytically indicate that a mixed region of metal and oxide formed at the metal/oxide interface includes the surface oxide charge, which allows for introducing an SOC term in the electron Hamiltonian. Based on the results, the SHA increases by two orders of magnitude in a Cu/oxide thin film through the side jump and skew scattering mechanisms, reaching that of heavy metals. In addition, a comprehensive model is provided for the influence of oxidation on the SHA and spin-orbit torques (SOTs) in FM/M structures. We find that the magnitude of SOTs is greatly dependent on (i) the surface oxidation condition, (ii) the current flow path, and (iii) the electronic interface condition. The model represented in the present study is regarded as a promising model and prediction mechanism which explains recent observations. The findings can be implemented in generating spin current without any use of external magnetic fields and heavy metals in spintronic devices.

Theory of the spin Hall effect in metal oxide structures

The spin Hall effect (SHE) has shown promising impact in the field of spintronics and magnonics from fundamental and practical points of view. This effect originates from several mechanisms of spin scatterers based on spin-orbit coupling (SOC) and also can be manipulated through the surface roughness. Here, the effect of correlated surface roughness on the SHE in metallic thin films with small SOC is investigated theoretically. Toward this, the self-affine fractal surface in the framework of the Born approximation is exploited. The surface roughness is described by the k-correlation model and is characterized by the roughness exponent H [Formula: see text], the in-plane correlation length ξ and the rms roughness amplitude δ. It is found that the spin Hall angle in metallic thin film increases by two orders of magnitude when H decreases from H  =  1 to H  =  0. In addition, the source of SHE for surface roughness with Gaussian profile distribution function is found to be mainly the side jump scattering while that with a non-Gaussian profile suggests both of the side jump and skew scatterings are present. Our achievements address how details of the surface roughness profile can adjust the SHE in non-heavy metals.

https://robots.iopscience.iop.org/article/10.1088/1361-648X/aab98a/pdf

Spin Hall effect originated from fractal surface.

Spin hall effect (SHE) in thin films is inherited by surface roughness. Although roughness effect on SHE has been studied in thin films, but roughness is not only parameter in rough surfaces. Our results show that how other statistical parameters of rough surface play important role in SHE. In this paper we investigate theoretically the effects of correlated surface roughness in the SHE with self affine fractal surface in non-heavy metallic thin films in the frame work of the Born approximation. The surface roughness is described by the k-correlation model and is characterized by the roughness exponent H (0 <= H <= 1), the in plane correlation length kesi and the rms roughness amplitude delta. We show that the spin Hall angle can increase by one order of magnitude when H decreasing from H = 1 to H = 0. We also demonstrate the SHE for surface roughness with distribution function of the Gaussian profile is mainly contributed by the side jump scattering while for that with a non-Gaussian profile, both side jump and skew scattering are present. our achievements demonstrate the important role of roughness texture profile for SHE in non-heavy metals.

I. Hajzadeh

Papers

Plasmonic improvement photoresponse of vertical-MoS2 nanostructure photodetector by Au nanoparticles

Facile, scalable and transfer free vertical-MoS2 nanostructures grown on Au/SiO2 patterned electrode for photodetector application

Theory of the spin Hall effect in metal oxide structures

Spin Hall effect originated from fractal surface.

Spin Hall effect originated from fractal surface