Recently, increasing research efforts have been made to exploit the enormous potential of nanotechnology and nanomaterial in the application of arsenic removal from water. As a result, there are myriad of types of nanomaterials being developed and studied for their arsenic removal capabilities. Nevertheless, challenges such as having a complete understanding of the material properties and removal mechanism make it difficult for researchers to engineer nanomaterials that are best suited for specific water treatment applications. In this review paper, a comprehensive review will be conducted on several selected categories of nanomaterials that possess promising prospects in arsenic removal application. The synthesis process, material properties, as well as arsenic removal performance and removal mechanisms of each of these nanomaterials will be discussed in detail. Fe-based nanomaterials, particularly iron oxide nanoparticles, have displayed advantages in arsenic removal due to their super-paramagnetic property. On the other hand, TiO ₂ -based nanomaterials are the best candidates as photocatalytic arsenic removal agents, having been reported to have more than 200-fold increase in adsorption capacity under UV light irradiation. Zr-based nanomaterials have among the largest BET active area for adsorption—up to 630 m ² g ⁻¹ —and it has been reported that amorphous ZrO ₂ performs better than crystalline ZrO ₂ nanoparticles, having about 1.77 times higher As(III) adsorption capacity. Although Cu-based nanomaterials are relatively uncommon as nano-adsorbents for arsenic in water, recent studies have demonstrated their potential in arsenic removal. CuO nanoparticles synthesized by Martinson et al were reported to have adsorption capacities up to 22.6 mg g ⁻¹ and 26.9 mg g ⁻¹ for As(V) and As(III) respectively. Among the nanomaterials that have been reviewed in this study, Mg-based nanomaterials were reported to have the highest maximum adsorption capacities for As(V) and As(III), at 378.79 mg g ⁻¹ and 643.84 mg g ⁻¹ respectively. By combining desired properties of different nanomaterials, composite nanomaterials can be made that have superior potential as efficient arsenic removal agents. Particularly, magnetic composite nanomaterials are interesting because the super-paramagnetic property, which allows efficient separation of nano-adsorbents in water, and high adsorption capacities, could be achieved simultaneously. For instance, Fe–Mn binary oxide nanowires have shown promising As(III) adsorption capacity at 171 mg g ⁻¹ . Generally, nanomaterials used for arsenic removal face severe degradation in performance in the presence of competing ions in water, especially phosphate ions. This study will contribute to future research in developing nanomaterials used for arsenic removal that are highly efficient, environmentally friendly and cost-effective by providing a thorough, structured and detailed review on various nanomaterial candidates that have promising potential.

Molybdenum (Mo) is the prominent choice as the back contact for various thin film solar cells such as CIGS, CZTS and CdTe. Physical vapour deposition (PVD) technique especially sputtering process has been chosen as the foremost method to deposit Mo thin film on top of desired substrate due to ease of parametric control of growth conditions. In this paper, we reported the effect of various RF power, operating pressure as well as temperature on Mo films on top of Mo sheet and soda lime glass (SLG) deposited using RF magnetron sputtering. Uniform surface morphology was obtained as RF power, operating pressure and deposition temperature were optimised. However, at higher deposition temperature less uniform surface was observed. XRD pattern of Mo films showed two different peak of and in case of Mo sheet and single peak in case of SLG. While peak intensity varies as deposition condition varies in case of Mo films deposited on Mo sheet. Electrical properties of Mo films on both Mo sheet and SLG were improved as RF power and deposition temperature are optimised. On the other hand, electrical properties are affected as operating pressure increased. Lower resistivity of 1.2x10-9Ω.m and 6.65x10-6Ω.m were found in case of Mo films deposited on Mo sheet and SLG. Surface roughness of 0.017 nm-19.32nm were found in case of Mo films deposited on Mo sheet and 0.002 nm-5.04nm were found in case of SLG. Roughness increased as RF power and deposition temperature increased. However, roughness decreased as operating pressure increased

Wireless sensor networks (WSNs) are spatially distributed sensor systems used to collect precise data from a large area of interest. WSN is usually deployed in the off-grid, and its widespread deployment is limited due to its requirement for the continuous and large amount of power. Energy harvesting has been recognized as a promising solution which has gained a lot of attention in recent years pertaining to enabling a self-sustainable operation of WSN. Radio Frequency (RF) is identified as an energy source that can be further used to harvest required energy for the WSN sensors. This paper outlines the motivation of RF energy harvesting for powering the WSN components. It is found that the rectenna circuit in RF harvester deals with very low amplitude of signals, and it requires further improvement in its feature and capabilities with reducing form factors. In this article, recent design and development consideration involved in rectenna circuit and corresponding performance trade-offs are being discussed. It also discusses the recent techniques involved in improving the overall power conversion efficiency of rectenna. The authors address the key challenging issues yet need to concentrate on further enhancements. This review will aid as a guide in the future, to develop an energy-efficient and high-performance RF harvester circuit, which needs to be taken to the next advance level.