Schiff Base Functionalized Cellulose: Towards Strong Support-Cobalt Nanoparticles Interactions for High Catalytic Performances

A new hybrid catalyst consisting of cobalt nanoparticles immobilized onto cellulose was developed. The cellulosic matrix is derived from date palm biomass waste, which was oxidized by sodium periodate to yield dialdehyde and was further derivatized by grafting orthoaminophenol as a metal ion complexing agent. The new hybrid catalyst was characterized by FT-IR, solid-state NMR, XRD, SEM, TEM, ICP, and XPS. The catalytic potential of the nanocatalyst was then evaluated in the catalytic hydrogenation of 4-nitrophenol to 4-aminophenol under mild experimental conditions in aqueous medium in the presence of NaBH4 at room temperature. The reaction achieved complete conversion within a short period of 7 min. The rate constant was calculated to be K = 8.7 × 10-3 s-1. The catalyst was recycled for eight cycles. Furthermore, we explored the application of the same catalyst for the hydrogenation of cinnamaldehyde using dihydrogen under different reaction conditions. The results obtained were highly promising, exhibiting both high conversion and excellent selectivity in cinnamyl alcohol.

The synergistic effect of carbon nanotubes and graphitic carbon nitride on the enhanced supercapacitor performance of cobalt diselenide-based composites

Carbon nanotubes and g-C₃N₄ synergistically optimize the electrical conductivity and spatial structure of CoSe₂, thus improving the performance of supercapacitors.

High performance cobalt nanoparticle catalysts supported by carbon for ozone decomposition: the effects of the cobalt particle size and hydrophobic carbon support

Catalytic gaseous ozone decomposition under high humidity is not only an urgent need but also a significant challenge because of the low stability over the available catalysts.

Yolk-shell ZIFs@SiO2 and its derived carbon composite as robust catalyst for peroxymonosulfate activation

Cobalt-based Zeolitic imidazolate frameworks (ZIFs) have shown a great potential for radical production by activating peroxymonosulfate (PMS). However, improve the stability of ZIFs in the reaction remains a significant challenge. In this work, ZIF-67 was synthesized and protected by coating with a layer of silica, furthermore, the yolk-shell ZIFs@SiO₂ was carbonized under inner gas to obtain the Co containing carbon. When the above samples were applied for catalytic degradation of Rhodamine B (RhB) in the presence of PMS, both of them shows similar performance, with higher RhB removal efficiency and stability than that of pure ZIF-67. Additionally, factors affecting the PMS activation such as catalyst and PMS dosage and solution pH were also investigated. Radical quenching tests and electron paramagnetic resonance (EPR) revealed that ¹O₂ was the dominant active species involving in the degradation process. Finally, the reusability of the catalysts was studied and the spent catalysts were analyzed. Overall, the results provide insights into synthesis of yolk-shell ZIFs@SiO₂ catalyst with enhanced performance for the degradation of organic pollutants from effluent.

Polyacrylic Acid Functionalized Co0.85Se Nanoparticles: An Ultrasmall pH-Responsive Nanocarrier for Synergistic Photothermal-Chemo Treatment of Cancer

To surmount the challenges of limited drug penetration and therapeutic resistance in solid tumors, stimuli-responsive nanocarrier-based drug delivery systems (DDSs) with relatively small sizes are inherently favorable for combined treatment of cancerous cells. In this work, poly(acrylic acid) (PAA) functionalized Co_0.85Se nanoparticles (PAA-Co_0.85Se NPs) were synthesized through an ambient aqueous precipitating approach for synergistic photothermal-chemo treatment of cancer. The obtained PAA-Co_0.85Se NPs possess ultrasmall size (8.2 ± 2.6 nm), considerable near-infrared (NIR) light absorption, high photothermal transforming efficiency (45.2%) and low cytotoxicity, all of which are beneficial for localized photothermal ablation of cancer cells. Doxorubicin hydrochloride (DOX·HCl) was then successfully loaded on PAA-Co_0.85Se NPs with a loading capacity up to 8.3% to form PAA-Co_0.85Se-DOX composites, which exhibited an exciting acidic pH-responsive drug release property due to the protonation of amino groups in DOX and carboxyl groups in PAA molecules. As expected, when HeLa cells were treated with PAA-Co_0.85Se-DOX NPs as well as NIR laser irradiation, a significant synergistic cell-killing effect was observed, greatly improving the treatment efficiency. Thus, this work presents novel insight into the design of ultrasmall stimuli-responsive nanocarrier-based DDSs for synergistic photothermal-chemo treatment of cancer cells.

Biosynthesis of the CuO nanoparticles using Euphorbia Chamaesyce leaf extract and investigation of their catalytic activity for the reduction of 4‐nitrophenol

Through this study an eco‐friendly, simple, efficient, cheap and biocompatible approach to the biosynthesis and stabilisation of CuO nanoparticles (NPs) using the Euphorbia Chamaesyce leaf extract is presented. The CuO NPs were monitored and characterised by field emission scanning electron microscopy, energy dispersive X‐ray spectroscopy, Fourier transformed infrared spectroscopy, transmission electron microscope and UV‐visible spectroscopy. The biosynthesised CuO NPs showed good catalytic activity for the reduction of 4‐nitrophenol (4‐NP) in water during 180 s and reused 4 times without considerable loss of activity.

Carbon-Coated Co(3+)-Rich Cobalt Selenide Derived from ZIF-67 for Efficient Electrochemical Water Oxidation

Oxygen evolution reaction (OER) electrocatalysts are confronted with challenges such as sluggish kinetics, low conductivity, and instability, restricting the development of water splitting. In this study, we report an efficient Co(3+)-rich cobalt selenide (Co0.85Se) nanoparticles coated with carbon shell as OER electrocatalyst, which are derived from zeolitic imidazolate framework (ZIF-67) precursor. It is proposed that the organic ligands in the ZIF-67 can effectively enrich and stabilize the Co(3+) ions in the inorganic-organic frameworks and subsequent carbon-coated nanoparticles. In alkaline media, the catalyst exhibits excellent OER performances, which are attributed to its abundant active sites, high conductivity, and superior kinetics.

Synthesis of TiO₂-loaded Co0.85Se thin films with heterostructure and their enhanced catalytic activity for p-nitrophenol reduction and hydrazine hydrate decomposition

P-nitrophenol (4-NP) and hydrazine hydrate are considered to be highly toxic pollutants in wastewater, and it is of great importance to remove them. Herein, TiO2-loaded Co0.85Se thin films with heterostructure were successfully synthesized by a hydrothermal route. The as-synthesized samples were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy and selective-area electron diffraction. The results demonstrate that TiO2 nanoparticles with a size of about 10 nm are easily loaded on the surface of graphene-like Co0.85Se nanofilms, and the NH3 · H2O plays an important role in the generation and crystallization of TiO2 nanoparticles. Brunauer-Emmett-Teller measurement shows that the obtained nanocomposites have a larger specific surface area (199.3 m(2) g(-1)) than that of Co0.85Se nanofilms (55.17 m(2) g(-1)) and TiO2 nanoparticles (19.49 m(2) g(-1)). The catalytic tests indicate Co0.85Se-TiO2 nanofilms have the highest activity for 4-NP reduction and hydrazine hydrate decomposition within 10 min and 8 min, respectively, compared with the corresponding precursor Co0.85Se nanofilms and TiO2 nanoparticles. The enhanced catalytic performance can be attributed to the larger specific surface area and higher rate of interfacial charge transfer in the heterojunction than that of the single components. In addition, recycling tests show that the as-synthesized sample presents stable conversion efficiency for 4-NP reduction.