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Rapid detection of toxic ions has taken great attention in the last few decades due to its importance in maintaining a greener environment for human beings. The extreme toxicity of cyanide (CN

Oxidation of toluene (an organic pollutant), into useful chemical products, is of great interest nowadays. However, efficient conversion of toluene under mild and sustainable conditions is a thought-provoking task. Here, we report MnMoO4 nanomaterials (CH1-CH2), synthesized through a very facile solvothermal approach. Catalytic efficiencies of MnMoO4 nanomaterials were evaluated by direct oxidation of toluene via C-H activation. Toluene was converted into benzaldehyde and benzyl alcohol in the presence of H2O2 as an oxidant at 80 °C. The reaction parameters, that is, catalyst dose, time, and toluene concentration, were varied to obtain the optimal conditions for the oxidation process. The 40.62% maximum toluene conversion rate was obtained after 18 h of oxidation activity with 0.06 g of catalyst CH1. A maximum of 78% benzaldehyde selectivity was obtained with 0.06 g of catalyst CH1 after 18 h of toluene oxidation activity. Also, 62.33% benzyl alcohol selectivity was achieved using 0.1 g of catalyst CH1 after 1 h of activity. Several catalytic cycles were run with CH1 to evaluate catalyst reusability. Potential % toluene conversion was obtained for up to six cycles and their turnover frequencies were found to be 1.94-1.01 s-1. FTIR spectra of catalyst CH1 before and after recovery indicate no significant change. The good conversion rate of toluene and efficient selectivity toward benzaldehyde and benzyl alcohol indicates the robustness and high potential of these catalysts to oxidize toluene under a milder, greener, and hazardous chlorine-free environment.

To maintain a green and sustainable environment for human beings, rapid detection of potentially toxic heavy metals like mercury (Hg(II)) has attracted great attention. Recently, sensors have been designed which can selectively detect Hg(II) over other common available cations and give a naked eye or fluorometric response. In the last two decades, the trend is shifting from bulky organic chemosensors toward nanoparticles due to their rapid response, low cost, eco-friendly and easy synthesis. In this review, promising nanoparticles-based sensors for Hg(II) detection are discussed. The nano-sensors are functionalized with nucleotide or other suitable materials which coordinate with Hg(II) ions and give clear color or fluorescence change. The operational mechanisms are discussed focusing on its four basic types. The nanoparticles-based sensors are even able to detect Hg in three different oxidation states (Hg(II), Hg(I) and Hg(0)). Recently, the trend has been shifted from ordinary nanoparticles to magnetic nanoparticles to simultaneously detect and remove Hg(II) ions from environmental samples. Furthermore, the nano-sensors for Hg(II) are compared with each other and with the reported organic chemosensors.

Carboxylate-based metal–organic frameworks (CMOFs) have received considerable attentions for their high stability, catalytic activity, and porosity. However, synthesis of CMOFs requires high temperature, pressure, and long reaction time. Here, we explored the activity of 2-methylimidazole (2-MIM) for ultrafast synthesis of CMOF nanostructures (CMOFNs), in aqueous medium at room temperature and reaction time of 10 min. Seven CMOFNs have been synthesized by using Al3+, Cr3+, Cu2+, Fe3+, In3+, or Cd2+ salt and 1,4-bezenedicarboxylic acid, or 1,3,5-benzenetricarboxylic acid. Through this technique, the CMOFs with space time yield 181–501 kg m−3 day−1 and crystal sizes of ca. 200–700 nm was obtained.

A single-step solution-based strategy is used to obtain 2D Janus-like free-standing ultrathin nanosheets build from two structurally unrelated species, that is, polyoxomolybdate (POM) and CoO. A controlled 2D-to-1D morphological transition was achieved by judiciously adjusting the solvent choice. These POM-CoO heterostructures can behave as an ideal catalyst for the epoxidation of styrene. Benefiting from their amphiphilic nature, these 2D POM-CoO nanosheets have also been used as surfactant to emulsify immiscible solvents. It is anticipated that structurally diverse polyoxometalates will offer promise as design elements for variety of structurally and compositionally tunable van der Waals integrated heteromaterials having a broad range applications.

Graphitic carbon material encasing chromium oxide nanoribbons [Cr 2 O 3 –C composite] is obtained by carbonizing a mixture of furfuryl alcohol and Cr-BDC MOF [BDC: benzene dicarboxylic acid; Cr 3 F(H 2 O) 2 O[(O 2 C)C 6 H 4 –(CO 2 )] 3 ·nH 2 O] at 900 °C under inert atmosphere. The Ni–Pd nanoparticles synthesized by NaBH 4 reduction method are loaded on the Cr 2 O 3 –C support via sonication. Morphological, structural, and chemical analysis of the designed chromia based carbon support and synthesized nanoparticles is carried out with PXRD, EDX, SEM, HR-TEM and BET surface area. The gas adsorption analyses reveal that BET surface area of Cr 2 O 3 –C support decreases from 438 m 2 g −1 to 171 m 2 g −1 by the incorporation Ni–Pd nanoparticles. The electro-oxidation reaction of methanol is carried out over the designed electrocatalysts in acidic media. The Ni–Pd nanoparticles supported on Cr 2 O 3 –C have presented a significant increase in catalytic activity for methanol oxidation and tolerance in comparison to the nanoparticles supported on activated carbon and glassy carbon electrode.

Novel graphitic material containing chromium oxide (Cr2O3) nanoribbons is obtained by carbonizing a mixture of polyfurfuryl alcohol and MIL–101(Cr) at 900 °C. Morphological, structural, and chemical analysis of the product is carried out with HR–TEM, SEM, XPS, XRD, and BET surface area. The maximum BET surface area recorded for the nanocomposite is 438 m2 g−1. The nanocomposite exhibits a specific capacitance as high as 300 F g−1 at 2 mV s−1 and 291 F g−1 at 0.25 A g−1, and presents 95.5% long–term cycling stability over 3000 cycles. The pseudo-capacitive role of Cr2O3 nanoribbons is found to be important towards total capacitance of nanocomposite material.

A synthesis strategy for the preparation of trimetallic PtCoFe alloy nanoparticle superlattices is reported. Trimetallic PtCoFe alloy monolayer array of nanoparticle superlattices with a large density of high index facets and platinum-rich surface are successfully prepared by coreduction of metal precursors in formamide solvent. The concentration of cetyl trimethyl ammonium bromide plays a vital role for the formation of a monolayer array of nanoparticle superlattices, while the size of nanoparticles is determined by NaI. The prepared monolayer array of nanoparticle superlattices is the superior catalyst for oxygen reduction reaction as well as for ethanol oxidation owing to their specific structural and compositional characteristics.