Borophene: a piezocatalyst for water remediation.

Borophene is an emerging two-dimensional material exhibiting exceptional piezocatalytic activity under the influence of ultrasonic vibrations, as exemplified herein by the decomposition of highly stable organic dyes in water. After 6 minutes of exposure, borophene sheets converted up to 92 percent of a mixture of dye molecules at room temperature.

Bacteria assisted green synthesis of copper oxide nanoparticles and their potential applications as antimicrobial agents and plant growth stimulants.

Copper oxide nanoparticles (CuO-NPs) have piqued the interest of agricultural researchers due to their potential application as fungicides, insecticides, and fertilizers. The Serratia sp. ZTB29 strain, which has the NCBI accession number MK773873, was a novel isolate used in this investigation that produced CuO-NPs. This strain can survive concentrations of copper as high as 22.5 mM and can also remove copper by synthesizing pure CuO-NPs. UV-VIS spectroscopy, DLS, Zeta potential, FTIR, TEM, and XRD techniques were used to investigate the pure form of CuO-NPs. The synthesized CuO-NPs were crystalline in nature (average size of 22 nm) with a monoclinic phase according to the XRD pattern. CuO-NPs were found to be polydisperse, spherical, and agglomeration-free. According to TEM and DLS inspection, they ranged in size from 20 to 40 nm, with a typical particle size of 28 nm. CuO-NPs were extremely stable, as demonstrated by their zeta potential of -15.4 mV. The ester (C=O), carboxyl (C=O), amine (NH), thiol (S-H), hydroxyl (OH), alkyne (C-H), and aromatic amine (C-N) groups from bacterial secretion were primarily responsible for reduction and stabilization of CuO-NPs revealed in an FTIR analysis. CuO-NPs at concentrations of 50 µg mL-1 and 200 µg mL-1 displayed antibacterial and antifungal activity against the plant pathogenic bacteria Xanthomonas sp. and pathogenic fungus Alternaria sp., respectively. The results of this investigation support the claims that CuO-NPs can be used as an efficient antimicrobial agent and nano-fertilizer, since, compared to the control and higher concentrations of CuO-NPs (100 mg L-1) considerably improved the growth characteristics of maize plants.

MIL-88B(Fe) MOF modified screen-printed electrodes for non-enzymatic electrochemical sensing of malathion.

An enzyme-free electrochemical approach for ultra-trace quantification of the organophosphate insecticide malathion is proposed in this study. It is premised on screen-printed carbon electrodes modified by the MIL-88B(Fe) metal-organic framework (MOF). A one-pot solvothermal method was used to synthesise MIL-88B(Fe). The surface modification of electrodes allowed for increased electroactive surface area and accelerated electron transport on the electrode. Inhibition in the redox signal of MIL-88B(Fe) was observed due to the affinity between metal centres of the MOF and the functional groups of malathion, leading to an accurate determination of malathion. The proposed sensor effectively quantified malathion in the wide concentration range of 1 × 10-12 M to 1 × 10-6 M. The limit of detection for malathion was 0.79 pM. The proposed sensor also possessed excellent stability, repeatability, and anti-interference characteristics. Furthermore, the proposed sensor demonstrated satisfactory malathion recovery in spiked vegetable samples.

NaNbO3/ZnO piezocatalyst for non-destructive tooth cleaning and antibacterial activity.

Tooth discoloration and plaque formation are serious issues for dental healthcare professionals across the world. Although traditional hydrogen peroxide-based cleaning methods are efficient, they can cause enamel demineralization, periodontal irritation, and toxicity. Also, these treatments are time-taking. Here, we present a noninvasive, safe, and simple tooth cleaning approach by using the piezoelectric phenomenon. After 6 h of vibrations, contaminated teeth can be significantly cleaned by the NaNbO3/ZnO binary nanocomposite. Moreover, the NaNbO3/ZnO binary nanocomposite-based piezocatalysis tooth cleaning procedure causes far less harm to enamel and biological cells in comparison to hydrogen peroxide-based cleaning methods. To evaluate its functionality, organic dyes were degraded by piezoelectric effect of NaNbO3/ZnO binary nanocomposite under ultrasonic irradiation. The piezoelectric potential of NaNbO3/ZnO was found to be 3.75 V. The binary nanocomposite's antibacterial activity was proven to be efficient against Escherichia coli with the inhibitory zone of 21 mm and complete removal of bacteria.

NaNbO3 Nanorods: Photopiezocatalysts for Elevated Bacterial Disinfection and Wastewater Treatment.

In the present work, ferroelectric sodium niobate (NaNbO3) nanorods are formulated to attain photopiezocatalysis for water pollutant degradation and bacterial disinfection. NaNbO3 nanorods, integrating the advantages of photocatalysis (generation of free charge carriers) and piezocatalysis (separation of these charge carriers), possess synergistic effects, which results in a higher catalytic activity than photocatalysis and piezocatalysis alone. Active species that are involved in the catalytic process are found to be •O2 - < OH• < h+, indicating the significance of piezocatalysis and photocatalysis. The degradation efficiency of sodium niobate (NaNbO3) nanorods for Rhodamine B in the presence of both sunlight and ultrasonic vibration is 98.9% within 60 min (k = 7.6 × 10-2 min-1). The piezo potential generated by NaNbO3 nanorods was reported to be 16 V. The antibacterial activity of the produced sample was found to be effective against Escherichia coli. With inhibitory zones of 23 mm, sodium niobate has a greater antibacterial activity.

Fabrication of LaFeO3 and rGO-LaFeO3 microspheres based gas sensors for detection of NO2 and CO.

In the present report, gas sensing devices based on LaFeO3 and rGO-LaFeO3 were fabricated by a photolithography technique. The X-ray diffraction, Raman spectra and FT-IR results confirm the formation of a perovskite phase and composite. XPS and TEM give the chemical compositions for both products. The higher roughness, greater surface area (62.1 m2 g-1), larger pore size (16.4 nm) and lower band gap (1.94 eV) of rGO-LaFeO3 make it a suitable candidate to obtain high sensitivity. The gas sensing performance of the devices was investigated for various concentrations of NO2 and CO gases at temperatures of 200 and 250 °C. It was observed that the rGO-LaFeO3 based device exhibited a high relative response (183.4%) for a 3 ppm concentration of NO2 at a 250 °C operating temperature. This higher response is attributed to the large surface area, greater surface roughness, and numerous active sites of rGO-LaFeO3. The gas sensing properties investigated show that rGO-LaFeO3 is an excellent candidate for an NO2 sensor.

A Polycarboxyl-Decorated FeIII -Based Xerogel-Derived Multifunctional Composite (Fe3 O4 /Fe/C) as an Efficient Electrode Material towards Oxygen Reduction Reaction and Supercapacitor Application.

Low cost, non-noble metal catalysts with a good oxygen reduction reaction (ORR) activity comparable to that of platinum and also having good energy storage properties are highly desirable but challenging. Several challenges are associated with the development of such materials. Herein, we demonstrate a new polycarboxyl-functionalised FeIII -based gel material, synthesised following a solvothermal method and the development of its composite (Fe3 O4 /Fe/C) by annealing at optimised temperature. The developed composite displayed excellent electrocatalytic activity for the oxygen reduction reaction with an onset potential of 0.87 V (vs. RHE) and a current density value of -5 mA cm-2 , which are comparable with commercial 20 wt % Pt/C. In addition, as one of the most desirable properties, the composite exhibits a better methanol tolerance and greater durability than Pt/C. The same material was explored as an energy storage material for supercapacitors, which showed a specific capacitance of 245 F g-1 at a current density of 1 A g-1 . It is expected that this Fe3 O4 /Fe/C composite with a disordered graphitised carbon matrix will pave a horizon for developing energy conversion and energy storage devices.

Efficient Electron Transfer across a ZnO-MoS2 -Reduced Graphene Oxide Heterojunction for Enhanced Sunlight-Driven Photocatalytic Hydrogen Evolution.

The development of noble metal-free catalysts for hydrogen evolution is required for energy applications. In this regard, ternary heterojunction nanocomposites consisting of ZnO nanoparticles anchored on MoS2 -RGO (RGO=reduced graphene oxide) nanosheets as heterogeneous catalysts show highly efficient photocatalytic H2 evolution. In the photocatalytic process, the catalyst dispersed in an electrolytic solution (S2- and SO32- ions) exhibits an enhanced rate of H2 evolution, and optimization experiments reveal that ZnO with 4.0 wt % of MoS2 -RGO nanosheets gives the highest photocatalytic H2 production of 28.616 mmol h-1 gcat-1 under sunlight irradiation; approximately 56 times higher than that on bare ZnO and several times higher than those of other ternary photocatalysts. The superior catalytic activity can be attributed to the in situ generation of ZnS, which leads to improved interfacial charge transfer to the MoS2 cocatalyst and RGO, which has plenty of active sites available for photocatalytic reactions. Recycling experiments also proved the stability of the optimized photocatalyst. In addition, the ternary nanocomposite displayed multifunctional properties for hydrogen evolution activity under electrocatalytic and photoelectrocatalytic conditions owing to the high electrode-electrolyte contact area. Thus, the present work provides very useful insights for the development of inexpensive, multifunctional catalysts without noble metal loading to achieve a high rate of H2 generation.