[en] The issue of dimerization is vital in determining the optical properties of dye-doped sol-gel materials and metallophthalocyanine offers an excellent opportunity to characterize dimmers from monomers because of their identified absorption bands. In this paper, zinc tetrasulfophthalocyanine (ZnTSPc) was encapsulated in silica-xerogel matrix by sol-gel technique. Dimerization of ZnTSPc was studied using UV-Vis optical absorption spectra, correlated with various stages of the sol-gel process. The results show that in the composites ZnTSPc concurrence in forms of monomer and dimmer, and dimerization behaves differently in the sol, gel and xerogel stages. Reasons are given from the change of the microenvironment of the composites in which ZnTSPc existed

[en] Metallophthalocyanine (MPc) and its composites have excellent photo-electricity properties. Here we report the study of MPc doped silica xerogel matrix obtained by sol-gel technique. Because the issue of dimerization is vital in determining the optical properties of dye doped sol-gel materials and MPc offers an excellent opportunity to characterize dimers from monomers because of their identified absorption bands, we studied the dimerization of different kinds of MPc doped silica composites using electronic absorption spectra. Changes in the absorption spectra were correlated with various stages of the sol-gel process. The results show that in the composite MPc molecules concurrence in forms of monomer and dimer, and dimerization is bad during the latter stages of drying because of the rapid decrease of remaining solvent and its ethanol/water ratio. To overcome this problem, a kind of dissociating agent Cremophor EL is added in order to protect the Zinc tetrasulfo-phthalocyanine molecules from dimerization. In the other hand, a newly developed in situ synthesis technique was successfully introduced to synthesize MPc during the sol-gel process. It is found that the in situ synthesized MPc only exist in the form of monomer in the composites

[en] Highlights: • Curvature of the SC-CNTs’ cavities had more local pressure, leading to form k-GNTs. • k-GNTs are divided into sections by knots with abundant edge-plane sites/defects. • k-GNTs exhibited excellent catalytic activity, sensitivity and reproducibility. - Abstract: Detection of disease-related small biomolecules was of great significance for clinical diagnostics and treatment. In this work, we synthesized defect-rich knotted graphene nanotubes (k-GNTs) via chemical oxidative etching of stacked-up carbon nanotubes (SC-CNTs) followed by chemical reduction, to detect disease-related small biomolecules. We further studied the electrochemical properties using three representative redox probes and analyzed their biosensitivity using five biomolecules. The k-GNT-modified electrodes exhibited excellent electrochemical response, with the lowest ΔE_p and the highest k⁰. Besides, the modified electrodes could simultaneously detect and discriminate between dopamine (DA), ascorbic acid and uric acid (UA), as well as differentiate phenethylamine (PEA) and epinephrine (EP) existed in newborn rat serum, providing the wide linear detection ranges with high sensitivities for DA, UA, PEA, and EP. These excellent electrocatalytic properties could be ascribe to the unique knotted graphene nanotube structure with high proportion of defect/edge sites, large, accessible, three-dimensional, accessible surface area, fewer oxygen-containing groups and doped N atoms. Our work reveals defect-rich k-GNTs as a promising platform for further applications in electrochemical biosensing and electrocatalysis.

[en] Nanostructured Ag in shapes of nanoplate, nanowire, and nanoparticle, as well as their silica gel glass composites have been prepared and characterized. Nonlinear optical (NLO) properties were measured at 532 and 1064 nm using open aperture z-scan technique and studied from the view of shape effect. NLO behaviors of the nanostructured Ag are found to be shape dependent in suspensions at both the investigated wavelengths, although they originate differently. Comparing to the mother suspensions, the Ag/silica gel glass nanocomposites present rather dissimilar NLO behaviors, which is quite interesting for further studies

[en] Three different graphene nanostructure suspensions of graphene oxide nanosheets (GONSs), graphene oxide nanoribbons (GONRs), and graphene oxide quantum dots (GOQDs) are prepared and characterized. Using a typical two-step method, the GONSs, GONRs, and GOQDs are incorporated into a polyimide (PI) matrix to synthesize graphene/PI composite films, whose nonlinear optical (NLO) and optical limiting (OL) properties are investigated at 532 nm in the nanosecond regime. The GONR suspension exhibits superior NLO and OL effects compared with those of GONSs and GOQDs because of its stronger nonlinear scattering and excited-state absorption. The graphene/PI composite films exhibit NLO and OL performance superior to that of their corresponding suspensions, which is attributed primarily to a combination of nonlinear mechanisms, charge transfer between graphene materials and PI, and the matrix effect

[en] A homogeneously translucent titanate nanobelt (TNB) suspension was prepared through facile surface modification of pristine TNBs by polymer wrapping with poly(allylamine hydrochloride). The resultant TNB aqueous suspension was found to remain stable for months. The nonlinear optical (NLO) and optical limiting (OL) properties of the TNB suspension were then investigated. We found that the TNB suspension behaves totally differently at 532 and 1064 nm excitation in the nanosecond laser pulse regime. The sample displays remarkable NLO and OL effects at 532 nm, originating from nonlinear scattering. However, the NLO and OL effects are entirely diminished at 1064 nm due to the absence of near-resonant absorption and the subsequent thermal effect.

[en] Highlights: • Hierarchical (Ni_0.33Co_0.67)Se₂ complex hollow spheres (CHSs) were synthesized via a simple method. • The hierarchical (Ni_0.33Co_0.67)Se₂ CHSs exhibited excellent electrochemical performance for pseudocapacitors. • An asymmetric supercapacitor based on the (Ni_0.33Co_0.67)Se₂ CHSs as positive electrode was also fabricated. Construction bimetallic transition metal selenides with complex hollow structures is of significant importance but also extremely challenging. In this work, starting form metal-organic frameworks (MOFs), we have successfully synthesized the unique hierarchical (Ni_0.33Co_0.67)Se₂ complex hollow spheres (CHSs), which manifest high specific capacitance as well as excellent rate performance and cycling stability, making them promising electrode materials for pseudocapacitors. The hierarchical (Ni_0.33Co_0.67)Se₂ CHSs display a high specific capacitance of 827.9 F g⁻¹ at the current density of 1 A g⁻¹ and can still retain 646.2 F g⁻¹ at a very high current density of 30 A g⁻¹. Besides, a high capacitance of 865.8 F g⁻¹ is obtained after cycling at 6 A g⁻¹ for 2000 cycles, indicating good cycling stability. The excellent electrochemical performance could be owing to their high electrical conductivity and hierarchical complex hollow structure. Furthermore, an asymmetric supercapacitor (ASC) device employing (Ni_0.33Co_0.67)Se₂ CHSs as positive electrode and activated carbon (AC) as negative electrode is also fabricated, which displays a high energy density of 29.1 Wh kg⁻¹ at a power density of 800 W kg⁻¹. These electrochemical results indicate the hierarchical (Ni_0.33Co_0.67)Se₂ CHSs could be promising electrode materials for pseudocapacitors. The present work might also contribute to the rational construction of metal selenides with complex hollow structures for high-performance energy storage.

[en] The implantation and growth of metal nanoparticles on graphene nanosheets (GNS) leads directly to severe damage to the regular structure of the graphene sheets, which disrupts the extended π conjugation, resulting in an impaired device performance. In this paper, we describe a facile approach for achieving the lossless formation of graphene composite decorated with tiny cadmium sulfide quantum dots (QDs) with excellent nonlinear optical properties by using benzyl mercaptan (BM) as the interlinker. The mercapto substituent of BM binds to the CdS QDs during their nucleation and growth process, and then the phenyl comes into contact with the GNS via the π-π stacking interaction. Using this strategy, CdS QDs with an average diameter of 3 nm are uniformly dispersed over the surface of graphene, and the resulting QD-graphene composite exhibits excellent optical limiting properties, mainly contributed by nonlinear scattering and nonlinear absorption, upon both 532 and 1064 nm excitations, in the nanosecond laser pulse regime.

[en] Poly(ethylene glycol) (PEG)/SiO₂-CaO-P₂O₅ hybrid xerogels were prepared using a room temperature sol-gel process. The advantage of this hybrid material over conventional composites is the molecular scale interactions between the bioactive inorganic components and the biodegradable organic components. Since PEG was added into the sol when the hydrolysis of tetraethoxysilane occurred, the molecular chain of PEG was penetrated into the SiO₂ networks to form a semi-IPN structure. Due to the excellent biocompatibility and aqueous solubility of PEG molecules, as well as the bioactivity of the inorganic components, the biological and mechanical properties of this hybrid xerogel exhibit great potential for bone regeneration applications. The formation of hydroxyapatite was observed when the xerogel was immersed into simulated body fluid, demonstrating good bioactivity of the hybrid. The cell toxicity test also demonstrated that the hybrid material is suitable for the proliferation of MC3T3-E1 cells. Thus, the PEG/SiO₂-CaO-P₂O₅ hybrid xerogel has great potential to meet the demands of bone regeneration materials. - Highlights: ► PEG was penetrated into the SiO₂ networks to form a semi-IPN structure. ► This hybrid xerogel exhibit great potential for bone regeneration applications. ► SEM micrographs confirm the bioactivity of the samples.

[en] Graphene and metal oxide nanocomposites have been demonstrated as promising electrode materials for high-performance lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). In this work, ultrafine CoMn₂O₄ nanoparticles uniformly anchored on reduced graphene oxide (rGO) sheets have been synthesized through a facile and effective two-step strategy. Owing to the rational combination of merits from both ternary CoMn₂O₄ and graphene sheets, the as-synthesized rGO/CoMn₂O₄ nanocomposite exhibits remarkable Li-battery performance with high reversible capacity, good cycling stability and excellent rate performance. Remarkably, the rGO/CoMn₂O₄ nanocomposite displays high reversible capacities of 1102.1 and 811.1 mA h g⁻¹ at the current densities of 200 and 500 mA g⁻¹ after 60 cycles, respectively. The discharge capacities of the rGO/CoMn₂O₄ nanocomposite are as high as 851.1, 835.3, 795.2, 755.9, 694.0, and 563.6 mA h g⁻¹ at the current densities of 100, 200, 500, 1000, 2000 and 5000 mA g⁻¹, respectively. These electrochemical results suggest the rGO/CoMn₂O₄ nanocomposite could be a promising anode material for high-performance LIBs. Besides, the rGO/CoMn₂O₄ nanocomposite also exhibits comparably promising electrochemical performance as an anode material for SIBs. Our study also highlights the importance of rational synthesis of graphene-based nanocomposite materials for high-performance LIBs and SIBs. - Graphical abstract: Ultrafine CoMn₂O₄ nanoparticles tightly anchored on reduced graphene oxide sheets have been synthesized, which exhibit good performance for lithium-ion batteries. - Highlights: • Small CoMn₂O₄ nanoparticles tightly anchored on reduced graphene oxide have been synthesized. • The rGO/CoMn₂O₄ nanocomposite exhibits good lithium and sodium storage performance. • This work highlights the importance of synthesizing graphene-based nanocomposite for LIBs and SIBs.