Tungsten oxide/graphene hybrid materials are attractive semiconductors for energy‐related applications. Herein, we report an asymmetric supercapacitor (ASC, HRG//m‐WO3 ASC), fabricated from monoclinic tungsten oxide (m‐WO3) nanoplates as a negative electrode and highly reduced graphene oxide (HRG) as a positive electrode material. The supercapacitor performance of the prepared electrodes was evaluated in an aqueous electrolyte (1 m H2SO4) using three‐ and two‐electrode systems. The HRG//m‐WO3 ASC exhibits a maximum specific capacitance of 389 F g−1 at a current density of 0.5 A g−1, with an associated high energy density of 93 Wh kg−1 at a power density of 500 W kg−1 in a wide 1.6 V operating potential window. In addition, the HRG//m‐WO3 ASC displays long‐term cycling stability, maintaining 92 % of the original specific capacitance after 5000 galvanostatic charge–discharge cycles. The m‐WO3 nanoplates were prepared hydrothermally while HRG was synthesized by a modified Hummers method.

The optoelectrical and magnetic characteristics of naturally existing iron-based nanostructures, especially hematite and magnetite nanoparticles (H-NPs and M-NPs), gained significant research interest in various applications, recently. The main purpose of this Review is to provide an overview of the utilization of H-NPs and M-NPs in various environmental remediation. Iron-based NPs are extensively explored to generate green energy from environmental friendly processes such as water splitting and CO2 conversion to hydrogen and low molecular weight hydrocarbons, respectively. The latter part of the Review provided a critical overview to use H-NPs and M-NPs for the detection and decontamination of inorganic and organic contaminants to counter the environmental pollution and toxicity challenge, which could ensure environmental sustainability and hygiene. Some of the future perspectives are comprehensively presented in the final portion of the script, optimiztically, and it is supported by some relevant literature surveys to predict the possible routes of H-NPs and M-NPs modifications that could enable researchers to use these NPs in more advanced environmental applications. The literature collection and discussion on the critical assessment of reserving the environmental sustainability challenges provided in this Review will be useful not only for experienced researchers but also for novices in the field.

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The search for clean, low-cost, and renewable energy sources is one important challenge of modern industrial societies. [1] Hydrogen generated by photochemistry has been identified as a promising energy carrier with high energy density and zero CO 2 emission while being environmentally clean. [2,3] To set up a light-driven and hydrogen based economy an exploration of new materials for eco-friendly, economically viable, stable, and efficient photocatalysts is needed. [4] Noble metals like platinum, iridium, and ruthenium are efficient catalysts for the electrolysis of water, but their scarcity and high-costs limit large-scale technological use. [5] The development of cheap and active catalysts with long-term stability for the hydrogen or oxygen evolution reaction in standard electrolytes is an important goal. A general method to carry out the fluorination of metal oxides with poly(tetrafluoroethylene) (PTFE, Teflon) waste by spark plasma sintering (SPS) on a minute scale with Teflon is reported. The potential of this new approach is highlighted by the following results. i) The tantalum oxyfluorides Ta 3 O 7 F and TaO 2 F are obtained from plastic scrap without using toxic or caustic chemicals for fluorination. ii) Short reaction times (minutes rather than days) reduce the process time the energy costs by almost three orders of magnitude. iii) The oxyfluorides Ta 3 O 7 F and TaO 2 F are produced in gram amounts of nanoparticles. Their synthesis can be upscaled to the kg range with industrial sintering equipment. iv) SPS processing changes the catalytic properties: while conventionally prepared Ta 3 O 7 F and TaO 2 F show little catalytic activity, SPS-prepared Ta 3 O 7 F and TaO 2 F exhibit high activity for photocatalytic oxygen evolution, reaching photoconversion efficiencies up to 24.7% and applied bias to photoconversion values of 0.86%. This study shows that the materials properties are dictated by the processing which poses new challenges to understand and predict the underlying factors.

-Nanotechnology has opened a new horizon of research in various fields including applied physics, chemistry, electronics, optics, robotics, biotechnology and medicine. In the biomedical field, nanomaterials have shown remarkable potential as theranostic agents. Materials which are considered inert are often used in nanomedicine owning to their nontoxic profile. At nanoscale, these inert materials have shown unique properties that differ from bulk and dissolved counterparts. In the case of metals, this unique behavior not only imparts paramount advantages but also confers toxicity due to their unwanted interaction with different cellular processes. In the literature, the toxicity of nanoparticles made from inert materials has been investigated and many of these have revealed toxic potential under specific conditions. The surge to understand underlying mechanism of toxicity has increased and different means have been employed to overcome toxicity problems associated with these agents. In this review, we have focused nanoparticles of three inert metallic materials i.e. gold, silver and iron as these are regarded as biologically inert in the bulk and dissolved form. These materials have gained wider research interest and studies indicating the toxicity of these materials are also emerging. Oxidative stress, physical binding and interference with intracellular signaling are the major role player in nanotoxicity and their predominance is highly dependent upon size, surface coating and administered dose of nanoparticles. Current strategies to overcome toxicity have also been reviewed in the light of recent literature. The authors also suggested that uniform testing standards and well-designed studies are needed to evaluate nanotoxicity of these materials that are otherwise considered as inert.