A highly luminescent iron(III)-based amino-functionalized metal-organic framework (MOF) of type NH
2
-MIL-101(Fe) was synthesized by a solvothermal method. Its structure and morphology were studied ...by X-ray diffraction, scanning electron microscopy, and FTIR. The strong fluorescence of the electron-rich MOF is shown to be quenched by electron-deficient nitroaromatic compounds. Compared to solvents such as water and other organic solvents, quenching by the nitroaromatic compounds nitrobenzene (NB), 4-nitrophenol (4-NP), 4-nitrotoluene (4-NT) and 1,3-dinitrobenzene (1,3-DNB) is particularly strong. The detection limits for NB, 4-NP, 4-NT and 1,3-DNB are 32 ppm, 17 ppm, 9.8 ppm and 11.5 ppm.
Graphical abstract
A highly luminescent iron(III)-based amino-functionalized metal-organic framework (MOF) of type NH
2
-MIL-101(Fe) was synthesized by a solvothermal method. The strong fluorescence of the electron-rich MOF is shown to be quenched by electron-deficient nitroaromatic compounds.
Herein, we report the facile synthesis of various benzimidazoles and benzothiazoles by using the NH
2
-MIL-125(Ti) MOF as an efficient oxidant-free heterogeneous catalyst with good yield. Adsorption ...of the substrate on the NH
2
-MIL-125(Ti) MOF surface through electron deficient Ti
4+
sites initiates the reaction. The broad substrate scope and high reusability of this catalyst are attractive for synthesis of a wide range of medicinally active benzimidazole and benzothiazole derivatives.
Herein, we report facile synthesis of various benzimidazoles and benzothiazoles by using the NH
2
-MIL-125(Ti) MOF as an efficient oxidant-free heterogeneous catalyst with good yield.
Extending the absorption to the visible region by tuning the optical band-gap of semiconductors and preventing charge carrier recombination are important parameters to achieve a higher efficiency in ...the field of photocatalysis. The inclusion of reduced graphene oxide (rGO) support in photocatalysts is one of the key strategies to address the above-mentioned issues. In this study, rGO supported AgI-mesoTiO2 photocatalysts were synthesized using a sonochemical approach. The physical effects of ultrasound not only improved the crystallinity of AgI-mesoTiO2 but also increased the surface area and loading of the AgI-mesoTiO2 nanocomposite on rGO sheets. The low intense oxygen functionalities (C-O-C and COOH groups) peak observed in the high resolution C1s spectrum of a hybrid AgI-mesoTiO2-rGO photocatalyst clearly confirmed the successful reduction of graphene oxide (GO) to rGO. The interfacial charge transfer between the rGO and the p-n junction of heterostructured photocatalysts has decreased the band-gap of the photocatalyst from 2.80 to 2.65 eV. Importantly, the integration of rGO into AgI-mesoTiO2 composites serves as a carrier separation centre and provides further insight into the electron transfer pathways of heterostructured nanocomposites. The individual effects of photo-generated electrons and holes over rGO on the photocatalytic degradation efficiency of rhodamine (RhB) and methyl orange (MO) using AgI-mesoTiO2-rGO photocatalysts were also studied. Our experimental results revealed that photo-generated superoxide (O2(-)˙) radicals are the main reactive species for the degradation of MO, whereas photo-generated holes (h(+)) are responsible for the degradation of RhB. As a result, 60% enhancement in MO degradation was observed in the presence of rGO in comparison to that of the pure AgI-mesoTiO2 photocatalyst. This is due to the good electron acceptor and the ultrafast electron transfer properties of rGO that can effectively reduce the molecular oxygen to produce a large amount of reactive O2(-)˙ radicals. However, in the case of RhB degradation, h(+) is the main reactive species which showed a slightly increased photocatalytic activity (12%) in the presence of rGO support where the role of rGO is almost negligible. This study suggests the effective roles of rGO for the degradation of organics, i.e., the rate of photocatalytic degradation also depends on the nature of compound rather than rGO support.
The development of new and efficient catalytic systems for solar light-driven hydrogen generation is one of the prime focuses of contemporary chemical sciences. Indeed, the charge carrier separation ...efficiency of a photocatalyst plays a vital role in photocatalysis. Herein, we have successfully designed a Cu2O-encapsulating NH2-MIL-125(Ti) MOF by a post-synthetic encapsulation strategy. The Cu2O-encapsulating MOF material showed a remarkable enhancement in photocatalytic H2 production activity under solar light illumination. Gratifyingly, the H2 production activity under solar light was around ∼28-fold higher than that of the pristine MOF. The enhancement in photocatalytic activity may be attributed to efficient charge carrier separation through Ti3+ sites and the broad light absorption of the Cu2O-encapsulating MOF photocatalyst. The possible electron transport mechanism, potential energy diagram (V vs. NHE), and the existence of Ti3+ ions have been demonstrated by various spectroscopic studies.
Photocatalysis is an effective approach for the removal of heavy metal ions present in the aquatic bodies. In this report, TiO
2
nanoparticles were successfully functionalized with 2-naphthol (2-NAP) ...using simple and scalable condensation reaction. The prepared photocatalyst was demonstrated as superior visible light photocatalyst for the effective reduction of Cr(
vi
). The 2-NAP functionalized TiO
2
displayed a remarkable enhancement in the photocatalytic reduction of Cr(
vi
) under visible light irradiation (
λ
> 400 nm). The maximum Cr(
vi
) reduction of about 100% (7 fold higher activity than bare TiO
2
) was achieved within 3 h. The discernible enhancement in the photocatalytic reduction of TiO
2
-2-NAP can be ascribed to improved optical absorption in visible region, high crystallinity of TiO
2
and high surface area. In addition, the photogenerated electron transfer from 2-NAP to TiO
2
(ligand to metal transfer) can significantly improved the photocatalytic performance than bare TiO
2
counterparts. Therefore, the functionalization of metal oxides with organic ligands can open new directions to overcome the existing limitations in photocatalysis.
Visible light active 2-naphthol functionalized TiO
2
(TiO
2
-2-NAP) photocatalytic system is developed for the 100% reduction of Cr(
vi
) in aqueous medium.
Early diagnosis of cardiovascular diseases (CVDs) has the potential to save millions of lives each year. Sensitive quantitative measurement of blood cardiac troponin I (cTnI) is required for early ...diagnosis of CVDs. Porous graphitic carbon nitride (PCN) nanomaterials integrated biosensor that detects picogram/mL concentrations of cTnI is reported. PCN is an updated version of graphitic carbon nitride (GCN) with improved porosity and electronic structure. A rapid two-step chemical method was described to synthesize PCN and gold nanoparticles functionalized PCN (PCN-AuNPs). The modification of the electrode surface with PCN materials had a significant impact on the electrochemically active surface area (EASA), interfacial electron transport, aptamer immobilization, and biosensing performance. The use of PCN nanomaterial in cTnI aptasensing resulted in a 3.2-fold increase in signal amplification. PCN-AuNPs found practically applicable in human blood serum (cTnI-spiked). Furthermore, a low-cost and user-friendly sensing platform has been demonstrated by integrating a PCN-AuNPs aptasensor, a custom-made miniaturized potentiostat, and a smartphone, which provided rapid, sensitive point-of-care (PoC) analysis of cTnI. Highly sensitive detection limit (0.01 pg/mL), rapid analysis time (2 min), and small sample volume (20 μL) are the other advantages of this nano-biosensor.
Display omitted
•Synthesis and characterization of porous g-C3N4 (PCN) and PCN-AuNPs materials.•PCN and PCN-AuNPs showed significantly increased electrochemical properties.•The cTnI aptasensing performance of PCN–Au is 3.2-times higher than g-C3N4.•Detection limit is 0.01 pg/mL covers clinical range for early diagnosis of AMI.•Integrated handheld point-of-care biosensing device is developed.
Combinations of different Advanced Oxidation Processes (AOPs) are being exploited for waste water treatment. The usage of ultrasound in photocatalysis finds much attention as the combined process ...offers some advantages over individual processes. Herein, we report the ultrasound assisted photocatalytic degradation of an organic pollutant (methyl orange as a model dye) in the presence of CuO-TiO2/rGO photocatalyst which was prepared by a simple wet impregnation method. A synergistic effect (3.7-fold) was observed by combining the sonolysis and photocatalysis processes. Influence of Cu loading and graphene oxide (GO) dosage over the photocatalytic performance of TiO2 was examined in detail. The catalyst dosage and initial concentration of MO were optimized based on a series of experimental studies. Besides, neutral pH was found to show an optimum efficiency for this sono-photocatalytic process.
•rGO/CuFe2O4-TiO2 (CTR) prepared via ultrasound assisted wet impregnation method.•A remarkable red shift of 1.51 eV was observed in the optical band gap of CTR.•The PL intensity of CTR attenuated ...almost 21 times in comparison to the bare TiO2.•35981 μmolg−1 h−1 of photocatalytic Hydrogen was produced by water splitting.
Reduced graphene oxide supported CuFe2O4-TiO2p-n heterojunction nanocomposite was prepared via ultrasound assisted simple wet impregnation method. The nanocomposites were characterized, by XRD, FTIR, Raman Spectra, FE-SEM, HR-TEM, UV- vis, DRS Spectra, and PL Spectra. The optical band gap of rGO/CuFe2O4-TiO2 nanocomposite was found to be red shifted to 1.51 eV from 3.20 eV for pristine TiO2 nanoparticles (NPs). The photocatalytic activity of the as-prepared rGO/CuFe2O4-TiO2 nanocomposite was determined via photocatalytic water-splitting in the presence of glycerol as hole scavenger under UV–vis light irradiation. A peak hydrogen production rate of 35981 μmolg−1 h−1 was obtained, which is ∼8 and 3 times higher than that of bare TiO2 (4640 μmolg−1 h−1) and CuFe2O4-TiO2 photocatalysts (14719 μmolg−1 h−1), respectively. This remarkable improvement in the photocatalytic activity can be attributed to the enhanced visible light absorption and efficient charge carrier separation at the interface of rGO/CuFe2O4-TiO2 nanocomposites. A significant quenching of photoluminescence intensity of the rGO/CuFe2O4-TiO2 nanocomposite further confirmed the effective separation and transportation of photogenerated charge carriers in the presence of rGO sheet. A double charge separation and transportation mechanism is proposed for the enhanced photocatalytic activity.
Solar water splitting provides a promising path for sustainable hydrogen production and solar energy storage. In recent times, metal–organic frameworks (MOFs) have received considerable attention as ...promising materials for diverse solar energy conversion applications. However, their photocatalytic performance is poor and rarely explored due to rapid electron–hole recombination. Herein, we have developed a material MOF@rGO that exhibits highly enhanced visible-light photocatalytic activity. A real-time investigation reveals that a strong π–π interaction between MOF and rGO is responsible for efficient separation of electron–hole pairs, and thereby enhances the photocatalytic hydrogen production activity. Surprisingly, MOF@rGO showed ∼9.1-fold enhanced photocatalytic hydrogen production activity compared to that of pristine MOF. In addition, it is worth mentioning here that remarkable apparent quantum efficiency (0.66%) is achieved by π–π interaction mediated charge carrier separation.
PDF
