Covalent functionalization of reduced graphene oxide with porphyrin by means of diazonium chemistry for nonlinear optical performance

Reduced graphene oxide (RGO)-porphyrin (TPP) nanohybrids (RGO-TPP 1 and RGO-TPP 2) were prepared by two synthetic routes that involve functionalization of the RGO using diazonium salts. The microscopic structures, morphology, photophysical properties and nonlinear optical performance of the resultant RGO-TPP nanohybrids were investigated. The covalent bonding of the porphyrin-functionalized-RGO nanohybrid materials was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and thermogravimetric analysis. Attachment of the porphyrin units to the surface of the RGO by diazotization significantly improves the solubility and ease of processing of these RGO-based nanohybrid materials. Ultraviolet/visible absorption and steady-state fluorescence studies indicate considerable π-π interactions and effective photo-induced electron and/or energy transfer between the porphyrin moieties and the extended π-system of RGO. The nonlinear optical properties of RGO-TPP 1 and RGO-TPP 2 were investigated by open-aperture Z-scan measurements at 532 nm with both 4 ns and 21 ps laser pulses, the results showing that the chemical nanohybrids exhibit improved nonlinear optical properties compared to those of the benchmark material C60, and the constituent RGO or porphyrins.Financial support from the National Natural Science Foundation of China (51432006, 50925207, 51172100), the Ministry of Science and Technology of China for the International Science Linkages Program (2011DFG52970), the Ministry of Education of China for the Changjiang Innovation Research Team (IRT14R23), the Ministry of Education and the State Administration of Foreign Experts Affairs for the 111 Project (B13025), and 100 Talents Program of CAS are gratefully acknowledged. M.G.H., C.Z. and M.P.C. thank the Australian Research Council (ARC) for support

Facile hydrothermal synthesis and optical limiting properties of TiO 2 -reduced graphene oxide nanocomposites

TiO2/reduced graphene oxide (RGO) nanocomposites Gx (RGO titania nanocomposite, x grams tetrabutyl titanate per 0.03 g RGO, x = 0.25, 0.50, 1.00) were prepared by a hydrothermal method: graphene oxide was reduced to RGO in a 2:1 water:ethanol mixture in the presence of varying quantities of tetrabutyl titanate, which deposited as TiO2 on the RGO sheets. The nanocomposites were characterized by a combination of Fourier transform infrared spectroscopy, diffuse reflectance ultraviolet-visible spectroscopy, photoluminescence spectroscopy, Raman spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy studies. The nanocomposite G0.25 exhibits enhanced nonlinear optical properties compared to its individual components, which is ascribed to a combination of mechanisms. The role of defects and electron/energy transfer in the optical limiting performance of G0.25 was clarified with the help of Raman and photoluminescence spectroscopies. Intensity-dependent switching between reverse saturable absorption and saturable absorption behavior was observed with the G0.50 nanocomposite

Thermal ablation as an alternative to liver transplantation for hepatocellular carcinoma with clinically significant portal hypertension: propensity score matching study

PurposeThe objectives were to investigate the safety and efficacy of thermal ablation as an alternative to liver transplantation for hepatocellular carcinoma patients with clinically significant portal hypertension (CSPH).Materials and MethodsFrom July 2016 to September 2019, hepatocellular carcinoma patients with CSPH treated by liver transplantation (N=37) or thermal ablation (N=114) were enrolled. Cumulative intrahepatic recurrence, overall survival and major complications were compared by propensity score matching.ResultsIn the two matched groups, the 1-, 2-, and 3-year intrahepatic recurrence rates for the ablation group (22.3%, 50.0%, and 50.0%, respectively) were significantly higher than those for the transplantation group (4.5%, 4.5%, and 4.5%, respectively) (P=0.016). The 1-, 2-, and 3-year overall survival rates were comparable between the two groups [96.1%, 88.7%, and 88.7%, respectively (ablation group) vs. 84.6%, 76.2%, and 76.2%, respectively (transplantation group)] (P=0.07). The major complication rate for the ablation group [4.8% (3/62)] was significantly lower than that for the transplantation group [36.0% (9/25)] (P<0.001).ConclusionsThermal ablation is a safe and effective alternative for hepatocellular carcinoma patients with CSPH

Flocculant-Assisted Synthesis of Graphene-Like Carbon Nanosheets for Oxygen Reduction Reaction and Supercapacitor

The rational treatment of hazardous textile sludge is critical and challenging for the environment and a sustainable future. Here, a water-soluble chitosan derivative was synthesized and used as an effective flocculant in removal of reactive dye from aqueous solution. Employing these chitosan-containing textile sludges as precursors, graphene-like carbon nanosheets were synthesized through simple one-step carbonization with the use of Fe (III) salt as graphitization catalyst. It was found that the resultant graphene-like carbon nanosheets material at thickness near 3.2 nm (NSC-Fe-2) showed a high graphitization degree, high specific surface area, and excellent bifunctional electrochemical performance. As-prepared NSC-Fe-2 catalyst exhibited excellent oxygen reduction reaction (ORR) activity (onset potential 1.05 V) and a much better methanol tolerance than that of commercial Pt/C (onset potential 0.98 V) in an alkaline medium. Additionally, as electrode materials for supercapacitors, NSC-Fe-2 also displayed an outstanding specific capacitance of 195 F g−1 at 1 A g−1 and superior cycling stability (loss of 3.4% after 2500 cycles). The good electrochemical properties of the as-prepared NSC-Fe materials could be attributed to the ultrathin graphene-like nanosheets structure and synergistic effects from codoping of iron and nitrogen. This work develops a simple but effective strategy for direct conversion of textile sewage sludge to value-added graphene-like carbon, which is considered as a promising alternative to fulfill the requirements of environment and energy

A 1,3-dipolar cycloaddition protocol to porphyrinfunctionalized reduced graphene oxide with a push-pull motif

Reduced graphene oxide (RGO) has been covalently functionalized with porphyrin moieties by two methods: A straightforward Prato reaction (i.e. a 1,3-dipolar cycloaddition) with sarcosine and a formyl-containing porphyrin, and a stepwise method that involves a 1,3-dipolar cycloaddition to the RGO surface using 4-hydroxybenzaldehyde, followed by nucleophilic substitution with an appropriate porphyrin. The chemical bonding of porphyrins to the RGO surface has been confirmed by ultraviolet/visible absorption, fluorescence, Fourier-transform infrared, and Raman spectroscopies, X-ray powder diffraction and X-ray photoelectron spectroscopy, transmission electron and atomic force microscopy, and thermogravimetric analysis; this chemical attachment assures efficient electron/energy transfer between RGO and the porphyrin, and affords improved optical nonlinearities compared to those of the RGO precursor and the pristine porphyrin.[Figure not available: see fulltext.

Functionalization of reduced graphene oxide with axially-coordinated metal-porphyrins: facile syntheses and temporally-dependent nonlinear optical properties

Reduced graphene oxide-tin porphyrin (RGO-SnTPP) nanohybrids with good dispersibility have been prepared by two covalent functionalization approaches. The microscopic structure and morphology of the RGO-SnTPP nanohybrids were characterized by various spectroscopic techniques including Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. Ground-state absorption and steady-state fluorescence studies indicate considerable π–π interactions and effective photo-induced electron and/or energy transfer from the porphyrin moieties to the RGO. Their nonlinear optical properties were investigated using the Z-scan technique at 532 nm with both picosecond and nanosecond laser pulses. The RGO-SnTPP hybrids were found to exhibit large nonlinear optical responses due to a combination of mechanisms, while significant differences in their nonlinear optical responses were observed, highlighting the influence on photophysical properties of the degree of functionalization and the synthetic approach employed.Financial support from the National Natural Science Foundation of China (51432006, 50925207, 51172100), the Ministry of Science and Technology of China for the International Science Linkages Program (2011DFG52970), the Ministry of Education of China for the Changjiang Innovation Research Team (IRT13R24), the Ministry of Education and the State Administration of Foreign Experts Affairs for the 111 Project (B13025), 100 Talents Program of CAS, and Jiangsu Innovation Research Team are gratefully acknowledged. M. G. H., M. P. C., and C. Z. thank the Australian Research Council (ARC) for support

TiO2-multi-walled carbon nanotube nanocomposites: Hydrothermal synthesis and temporally-dependent optical properties

Multi-walled carbon nanotube (MWCNT)/TiO2 nanocomposites have been prepared by a hydrothermal method and characterized by Fourier-transform infrared, Raman, and X-ray photoelectron spectroscopies, X-ray powder diffraction, and transmission electron microscopy. Their viability as nonlinear optical (NLO) materials has been examined using the Z-scan technique at 532 nm with both nanosecond and picosecond laser pulses, the NLO and optical limiting (OL) performance being found to be dependent on the TiO2 content. At the wavelength used, an enhanced OL response was observed for the M1.00 nanocomposite and ascribed to a combination of mechanisms

Cooperative enhancement of optical nonlinearities in a porphyrin derivative bearing a pyrimidine chromophore at the periphery

A novel porphyrin derivative bearing one D-π-A-π-D pyrimidine chromophore at the periphery was designed, prepared, and studied using the Z-scan technique, the results showing that this compound exhibits enhanced nonlinear optical (NLO) absorption, refr

Facile synthesis and enhanced nonlinear optical properties of porphyrin-functionalized multi-walled carbon nanotubes

Two multi-walled carbon nanotube (MWCNT)-based nanohy-brids, MWCNT-ZnTPP and MWCNT-TPP (TPP=5-[4-{2-(4-formylphenoxy)-ethyloxy}phenyl]-10, 15, 20-triphenylpor-phyrin, ZnTPP=5-[4-{(4-formylphen-yl)ethynyl}phenyl]-10, 15, 20-triphenyl-porphinatozinc(II)),