•Hydrophobic nanoparticles were fabricated within the channels of mesoporous silica.•Tailoring both curvature and hydrophobicity of channel wall at the same time.•Hydrophobicity and geometric confinement accelerate liquid adsorption of TSNA.•150% increasing the capacity of SBA-15 in liquid adsorption of TSNA.Based on the synthesis of super hydrophobic silicic xerogel (SG) from methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS), siliceous hydrophobic nanoparticles were fabricated within the mesoporous channels of SBA-15, in order to enhance the efficiency of adsorbing tobacco specific N-nitrosamines (TSNA) in aqueous solution. The concentration of precursor solution was adjusted to master the distribution of hydrophobic particles and the mean hydrophobicity of resulting composite, 150% increasing the capacity of SBA-15 in liquid adsorption of TSNA.

A two-dimensional imide-based conjugated polymer with a preferred (001) orientation was constructed by solvent-induced assembly. A high performance of 1640 μmol h−1 g−1 for solar-driven photocatalytic hydrogen evolution and an excellent stability were achieved due to tunnelling charge transport between the neighbouring molecular sheets.

A two-dimensional imide-based conjugated polymer with a preferred (001) orientation was constructed by solvent-induced assembly. A high performance of 1640 μmol h−1 g−1 for solar-driven photocatalytic hydrogen evolution and an excellent stability were achieved due to tunnelling charge transport between the neighbouring molecular sheets.

A monolayer MoS2 quantum dot confined polyimide (MQDs/PI) photocatalyst was synthesized by using a facile immersion-hydrothermal method. The investigations on the optical and electronic properties of MQDs/PI composites reveal that the strong quantum confinement effect of MQDs results in a blue-shift of the absorption band edge of PI, and the interfacial electronic interaction between MQDs and PI improves the charge transfer rate of MQDs/PI. The ultra-small size of 3.0 nm and perfect crystals of MQDs endow MQDs/PI composites with plenty of active sites and fast charge transfer, thus resulting in a 360% enhancement in photocatalytic hydrogen production compared with that of Pt/PI at the same loading amount of Pt. This discovery provides a new clue for the development of an efficient and sustainable non-noble metal photocatalyst.

•HZSM-5 zeolite is excellent to trap TSNA in aqueous solution.•HZSM-5 catalyzes NNK and NNN at lower temperature than that of pyrolysis.•Adsorption of TSNA in tobacco solution is more efficient than that in smoke.HZSM-5 zeolite was used to conquer the challenge of liquid adsorption of tobacco specific N-nitrosamines (TSNA), either in aqueous solution or tobacco extract solution, offering a candidate with an optimal Si/Al ratio and channel structure to capture the carcinogens. It could trap 84% of N′-nitrosonornicotine (NNN) and 99% of 4-methylnitrosamino-1-3-pyridyl-1-butanone (NNK) in aqueous solution, much better than that by NaZSM-5 zeolite. Both FTIR and TG/MS technologies were employed to study the adsorption and catalytic degradation of NNN and NNK by HZSM-5 zeolite. The N–N bond of NNK was broken in the range of 423–573 K and the pyridine fragments appeared at 630 K due to the breakage of C–C bond between pyridine and carbonyl groups. Besides, HZSM-5 zeolite was sprayed on the rod of cigarette and smoked with different manners for the first time, in order to assess its function of reducing TSNA content in mainstream smoke and compared with that of liquid adsorption.HZSM-5 zeolite efficiently traps TSNA in aqueous solution and catalyzes them at lower temperature than that of pyrolysis.Download high-res image (139KB)Download full-size image

A new synthetic strategy, named “carbonization in limited space” and based on the specific interaction between eutectic salt and dual-ionic liquids (dual-ILs), is reported in this article. N-Containing dual-ILs (1,4-diethyl-1,4-diazaniabicyclo[2,2,2]octane imidazolide-4,5-dicyanoiazolide, [2C2DABCO]2+[Im]−[CN-Im]−) were synthesized as new carbon–nitrogen precursors, while eutectic salt was chosen as a reuseable template in order to facilely fabricate the N-doped porous carbon with sheetlike morphology. Nitrogen can be directly and efficiently incorporated into the porous carbon, resulting in the materials with suitable N content, tunable pore structure, and controllable thickness of sheet as well as high surface area. They exhibited good performance as electrodes for supercapacitors, photocatalysts in degradation of methyl orange (MO) under visible light, and the sorbent to capture tobacco-specific N-nitrosamines (TSNAs) in solution, offering a new simplified but effective method to prepare versatile carbon material.Keywords: adsorbents; dual-ionic liquids (dual-ILs); heteroatom-doped porous carbon; photocatalysis; supercapacitors

To fabricate a new solid base with high efficiency in the adsorption of CO2 at 473 K and catalytic activity in the degradation of nitrosamines, magnesium oxalate and copper nitrate are mixed with the assistance of microwave irradiation followed by calcination to immobilize CuO among MgO particles. The binary solid base CuO–MgO is thus moderately reduced to form the Cu-inserted MgO composite with highly exposed strong basic sites, and it can capture 34.6 mg g–1 of CO2 in the harsh instantaneous adsorption at 473 K and keep a high strong basicity while trapping the CO2 mixed with SO2 and NO. Besides this, the new solid base exhibits high activity in the removal of volatile nitrosamine N-nitrosopyrrolidine (NPYR), for the first time expanding the application of solid bases to environmental catalysis.Keywords: catalytic degradation; CO2 adsorption; Cu; MgO; NPYR; solid base

A novel two-dimensional hybrid polymer photocatalyst black-MoO3/polyimide was synthesized by one-pot thermopolymerization of monomers, ammonium molybdate, and thiourea at mild temperatures. Thiourea and ammonium molybdate as fluxing agents promote the formation of black molybdenum oxide (BMO) on polyimide (PI) and enhance the crystallinity of PI. It is confirmed by X-ray photoelectron spectroscopy, electron paramagnetic resonance, and Fourier transform infrared that the strong interaction between BMO and PI leads to the formation of a Mo–N coordination bond through the coordination of N atoms of heptazine units to the unsaturated Mo atoms of BMO and results in a large number of Mo5+ cations in BMO/PI. UV–vis and photoluminescence reveal that the visible light absorption of BMO/PI was increased and the separation efficiency of photogenerated electron/hole obviously was significantly enhanced, which facilitates the improvement of the photocatalytic activity of BMO/PI. This work provides a new approach to synthesizing efficient inorganic–organic hybrid semiconductor photocatalysts.Keywords: degradation; hybrid photocatalyst; molybdenum trioxide; polyimide; visible light irradiation;

A series of Fe-doped SH/TiO2 mesoporous photocatalysts have been firstly prepared by one-pot method using P123 as structure-directing agent. This bifunctionalized mesoporous TiO2 possesses perfect anatase crystal structure and high surface area. The surface area of Fe-doped SH/TiO2 mesoporous material is 4 times higher than that of P25. Based on the EPR results, it was found that trivalent Fe ions exist at low spin state and substitutes a part of Ti4+ ions into TiO2 lattice. Fe-dropping in TiO2 extends the adsorption band side of the resulting material to about 600 nm. Much high photocatalytic activity in the degradation of phenanthrene was obtained on the bifunctionalized mesoporous TiO2 under visible light irradiation (λ > 420 nm), which is 6 times higher than that of pristine mesoporous TiO2. The enhancement in the photocatalytic activity of bifunctionalized TiO2 is ascribed to the extended absorption to visible light and strong interaction between SH-groups and PHE molecules.

Sulfur-doped polyimide (SPI) photocatalysts were synthesized for the first time via an in situ thermal copolymerization method using sublimed sulfur (S4) as a dopant. Sulfur doping not only extended the absorption range of polyimide (PI) for visible light but also enhanced the oxidation ability of the photoinduced hole. The doped sulfur substitutes for the lattice nitrogen in triazine rings of PI to form the S–C bond and changes the distribution of negative charge in the two-dimensional plane of PI. The enhanced photocatalytic activity of SPI in the degradation of methyl orange is ascribed to the strong oxidation ability of the photoinduced hole of SPI and an effective suppression to the recombination of electrons and holes.Keywords: degradation; photocatalyst; polyimide; sulfur doping; visible light;

In this study, a series of conjugated polyimide (PI) photocatalysts were prepared via a facile thermal condensation of melamine and various aromatic dianhydride monomers. The samples were characterized by Fourier transform infrared spectroscopy, elemental analysis, X-ray powder diffraction and UV-vis diffuse reflectance spectroscopy. All samples showed a well-developed polyimide structure and strong visible-light absorption. The electronic band structures of PI were simulated by density functional theory calculations. Photocatalytic results showed that the PI with a best coplanar conformation in the backbone and strongest photooxidative capability exhibited the highest activity for methyl orange (MO) degradation. In addition, it displayed an excellent stability during four cycles of photocatalytic testing. Photocatalytic mechanism study indicated that photogenerated holes rather than electrons play a crucial role on the photodegradation of MO. Moreover, the participation of reactive oxygen species such as OH˙, O2˙− and 1O2 was examined by adding corresponding scavengers. However, only 1O2 was identified as the active species involved in the MO degradation. This work represents the great potential of metal-free PI photocatalyst as sustainable, efficient and low-cost material for environmental remediation and solar energy conversion.

•Melem is found as a metal-free unit for photocatalytic hydrogen evolution.•Conjugating melem with dianhydride monomer greatly enhances visible-light absorbance and photocatalytic performance.•This work sheds light on developing novel metal-free photocatalysts based on melem unit.Melem, the building unit of g-C3N4, is reported for the first time as a metal-free photocatalyst for hydrogen evolution from methanol aqueous solution. Melem is synthesized via a facile thermal condensation of melamine at 425 °C. Its chemical structure is verified by the combination of Fourier transform infrared spectroscopy (FTIR), solid-state 13C nuclear magnetic resonance (NMR) and elemental analysis. Density functional theory (DFT) calculations reveal that melem possesses frontier orbitals quite similar to those of g-C3N4. By conjugating melem with dianhydride monomer, an extended polyimide network with greatly enhanced visible-light absorption is formed. Consequently, the visible-light activity for hydrogen evolution is enhanced by six times and reaches to a rate of 13.1 μmol/h. This work may open up new opportunity to develop efficient metal-free photocatalysts based on melem unit.

The electronic band structure of a semiconductor photocatalyst intrinsically controls its level of conduction band (CB) and valence band (VB) and, thus, influences its activity for different photocatalytic reactions. Here, we report a simple bottom-up strategy to rationally tune the band structure of graphitic carbon nitride (g-C3N4). By incorporating electron-deficient pyromellitic dianhydride (PMDA) monomer into the network of g-C3N4, the VB position can be largely decreased and, thus, gives a strong photooxidation capability. Consequently, the modified photocatalyst shows preferential activity for water oxidation over water reduction in comparison with g-C3N4. More strikingly, the active species involved in the photodegradation of methyl orange switches from photogenerated electrons to holes after band structure engineering. This work may provide guidance on designing efficient polymer photocatalysts with the desirable electronic structure for specific photoreactions.Keywords: band structure; dye degradation; photocatalysis; polyimide; water splitting

A polymeric photocatalyst was synthesized by coupling p-nitrobenzoic acid (PNA) onto graphitic carbon nitride (g-C3N4). The as-synthesized polymeric photocatalyst (PNA–g-C3N4) has a higher performance in the photodegradation of methyl orange (MO) than does g-C3N4. UV results show that PNA–g-C3N4 can harvest more solar energy than g-C3N4. Fluorescence results indicate that the separation efficiency of photo-induced electrons and holes in PNA–g-C3N4 is higher than that in g-C3N4. According to the experimental results and theoretical calculations, coupling PNA with g-C3N4 can narrow the band gap and introduce a gradient in the electronic potential distribution on the polymeric photocatalyst surface. The former results in the polymeric photocatalyst harvesting more solar energy, while the latter will favor the separation of photo-induced electrons and holes.

A series of polyimide photocatalysts with different polymerization degrees were prepared by thermal condensation of melamine and pyromellitic dianhydride at different condensation temperatures between 250 °C and 350 °C. Fourier transform infrared (FT-IR) spectra, X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) revealed that the polymerization degree increased with increasing condensation temperature. UV–Vis absorption spectra showed that the bandgap energy was lineally decreased with the increase of temperature. The theoretical calculations indicated that the level of conduction band downshifted and valence band upshifted upon the bandgap narrowing. Photocatalytic results displayed that the sample with moderate bandgap exhibited the highest H2 evolution activity, which adapted the balance among many factors such as light absorption, band potentials, crystallinity, particle size and surface area.Highlights► Polyimide photocatalysts with different degree of polymerization are prepared. ► The polymerization degree greatly depends on thermal condensation temperature. ► The bandgap decreases with increasing polymerization degree. ► Polyimide with moderate bandgap shows the highest photocatalytic activity. ► The bandgap engineering method is expected to prepare other efficient polymer photocatalysts.

A simple green process based on thermal condensation is developed to synthesize polyimide. The obtained product possesses a high degree of crystallinity and exhibits efficient photocatalytic activity for hydrogen production from water under visible light.

A N–O bond is introduced into hyperbranched polyimide photocatalysts for the first time to change their polarity and modulate electronic structure. Both of the changes help improve the photocatalytic ability of the polyimide. This strategy shows great prospect for synthesizing effective organic photocatalysts.

A new class of periodic mesoporous organosilicas (PMOs), which contains various hydrophilic groups of –OH, –O– and –S–, is successfully synthesized with novel bridged organosilica precursor under the acid-catalyzed and inorganic-salt-assisted conditions. These hybrid materials possess the ordered mesostructure with uniform pore size distributions, thick framework walls, thermal stability and specific functional groups; and they are carefully characterized by XRD, N2 adsorption, TGA, FT-IR, TEM and NMR spectroscopies. Moreover, horseradish peroxidase (HRP) is immobilized on these new PMO composites for the first time, and their enzyme activity in the oxidation of 1,3,5-trimethylbenzene (TMB) is elevated in the range of 25–59% compared with that of free HRP in solution. Again, the HRP immobilized samples can be reused for many cycles, resulting from the interfacial activation of the enzyme when it is attached to the surface of hybrid hosts where is filled with organic groups and hydrophobic parts.Graphical abstractThe relative activity of immobilized HRP on new mesoporous organosilica is all dramatically improved.Highlights► New mesoporous organosilicas with hydrophilic groups of –OH, –O– and –S– is synthesized. ► The resulting PMOs composites MGn have ordered 2D hexagonal mesoporous structure. ► HRP is immobilized in various MGn materials to catalyze oxidation of TMB. ► HRP/MGn catalysts have 25–59% higher activity than that of free HRP in solution. ► The HRP immobilized on PMO samples can be reusable.

A visible light triggered protein delivery system has been assembled through hydroxyl coordinated onto titania nanoparticles. Biomolecules such as hemoglobin (Hb) can be controlled-released from the hybrid material TiO2–DB–Hb by switching visible light on/off. The released Hb not only retains its senior structure but also can fulfil the enzymatic bioactivity. Controlled delivery of Hb stems from the scission of the Ti–O coordination bond with the aid of photo-inducing electron transfer property of titania.

In order to establish the hierarchical structure in multiple levels on mesoporous silica, this article reports a new strategy to prepare the monolith with the pore configuration in nanometer scale, micro-morphology in micrometer level and macroscopic shape in millimeter or larger grade. These hierarchical monoliths are synthesized in a weak acidic condition by using triblock copolymer P123, hydroxyl carboxylic acid and tetramethyl orthosilicate (TMOS), and the textural properties of the mesostructure can be facilely adjusted by simply controlling the synthesis condition without any additive. During the synthesis, the primary particles can be selectively synthesized as monodispersed sphere, noodle, prism, straight rods with different size or irregular bars, and their connection plus arrangement in 3D directions can be also regulated. Therefore, various textural properties of mesopore are able to be altered including pore size (5.5–10.6 nm), total pore volume (0.48–1.2 cm3 g−1), micropore surface area (47–334 m2 g−1), and pore shape (from 2D or 3D straight channel to plugged channel). Moreover, these monoliths exhibit a considerable mechanical strength; they are also applied in eliminating particulate matters and tobacco special nitrosamines (TSNA) in tobacco smoke, exhibiting various morphology-assisted functions.Graphical abstractHierarchical mesoporous silica monoliths with high mechanical intensity, tunable 3D net-liked framework and textural properties were synthesized in hydroxyl carboxylic acids route.Highlights► Using hydroxyl carboxylic acids to create a weak acidic synthetic condition. ► Adjusting the resembling process of micro-morphology to mesostructure. ► Hierarchical monoliths exhibit a high mechanical strength up to 25 N cm−2. ► Efficiently eliminate particulate matters and tobacco special nitrosamines in smoke.

This article reports a bifunctionalized mesoporous ZrO2/SBA-15 materials prepared through a simplified one-pot synthesis, in which the aged sample was evaporated with mother solution under the self-adjusted pH condition. The results of low-angle XRD, HRTEM, nitrogen adsorption-desorption, in-situ 1H NMR and NH3-TPD tests confirmed the well-ordered hexagonal structure and large pore size of these composites along with the newly formed acidity and basicity. Temperature programmed surface reaction (TPSR) was employed to assess the catalytic function of ZrO2/SBA-15 composites on the degradation of carcinogenic volatile nitrosamines such as N-nitrosopyrrolidine (NPYR). Due to the special interaction between the N–NO group of nitrosamines and the acidic site of mesoporous composite, NPYR could be efficiently trapped and then catalytic degraded at lower temperature, which enables this functional composite to be a new candidate for environment protection.Highlights► A bifunctionalized mesoporous composite ZrO2/SBA-15 is prepared by one-pot method. ► pH self-adjusting of the system facilitates the high framework insertion of zirconium. ► Framework Zr and high dispersed zirconia result in coexisting of acid-basic sites. ► ZrO2/SBA-15 is active for cracking carcinogenic nitrosamine at lower temperature. ► Strong interaction between acidic site and N–NO group leads cracking of nitrosamine.

In this paper, a thiol-functionalized nanophotocatalyst MPTES/TiO2 was first synthesized by one-pot method using P123 as a template. X-ray diffraction confirms the complete anatase crystalline of thiol-functionalized TiO2, N2 adsorption–desorption isotherm demonstrated that these materials possess high surface area and mesoporous structure. The results of XPS show that MPTES has been successfully polymerized in mesoporous structured TiO2. The photodegradation of phenanthrene (PHE) was investigated under visible light irradiation (λ > 420 nm) to evaluate the photocatalytic activity of these materials. Based the experiment results of GC–Mass analysis, a possible mechanism was proposed.

A sensitive fluorescent chemosensor based on bis-Schiff base N,N′-(1,4-phenylenedimethylidyne) bis-1,4-benzenediamine (PMBA) was developed for detection of Al3+ in aqueous solutions. A naked eye color variation from yellow to colorless is observed along with a remarkable fluorescence enhancement. A good linearity between the fluorescence intensity of the coordinate complex Al3+-PMBA and the concentration of Al3+ (0–30 μM/L), with a detection limit of 2 × 10−6 M was established.A sensitive fluorescence chemosensor for Al3+ based on bis-Schiff base PMBA was developed. A naked eye color change form light yellow to colorless with a remarkable fluorescence enhancement of PMBA in the presence of Al3+ is contributed to the formation of new coordinate complex.

In this work, a series of novel Co-In layered photocatalysts with varying Co/In mole ratio were designed and synthesized by using narrow band gap indium as the layer element. XRD, N2 adsorption-desorption technique and UV-vis spectrum were utilized to characterize the texture and the photo-adsorption property of the Co-In LDH samples. XRD result indicates that the samples possess hydrotalcite-like layered structure, and UV-vis spectrum depicts these materials have good absorption to visible light. The photo-adsorption property of the samples is dependent on its Co/In mole ratio. The calcined LDH materials showed high photocatalytic activity on the degradation of Methylene Blue (MB) under visible light irradiation, which is related to the formation of Co(III).

•New molecular recognition of NaZSM-5 zeolite between NNK and NNN.•NNK was safely degraded under 600 K by zeolite.•First evidence on the insert-adsorption of NNN in zeolite.Adsorption of 4-methylnitrosamino-1-3-pyridyl-1-butanone (NNK) along with N’-nitrosonornicotine (NNN) in water is studied for the first time with the monitoring of LC-MS/MS. In the mixed aqueous solution of NNK and NNN, NaZSM-5 zeolite uniquely captured NNK but refused NNN. And the influence of initial concentration, adsorption time and type of sorbents were systemically investigated. Degradation of NNK adsorbed on zeolite is studied with TG/MS and FTIR methods for the first time. It was degraded to NO, pyridine, amine and propanal at around 600 K, avoiding formation of volatile nitrosamines and secondary pollution.

A polymeric photocatalyst was synthesized by coupling p-nitrobenzoic acid (PNA) onto graphitic carbon nitride (g-C3N4). The as-synthesized polymeric photocatalyst (PNA–g-C3N4) has a higher performance in the photodegradation of methyl orange (MO) than does g-C3N4. UV results show that PNA–g-C3N4 can harvest more solar energy than g-C3N4. Fluorescence results indicate that the separation efficiency of photo-induced electrons and holes in PNA–g-C3N4 is higher than that in g-C3N4. According to the experimental results and theoretical calculations, coupling PNA with g-C3N4 can narrow the band gap and introduce a gradient in the electronic potential distribution on the polymeric photocatalyst surface. The former results in the polymeric photocatalyst harvesting more solar energy, while the latter will favor the separation of photo-induced electrons and holes.

A N–O bond is introduced into hyperbranched polyimide photocatalysts for the first time to change their polarity and modulate electronic structure. Both of the changes help improve the photocatalytic ability of the polyimide. This strategy shows great prospect for synthesizing effective organic photocatalysts.

A visible light triggered protein delivery system has been assembled through hydroxyl coordinated onto titania nanoparticles. Biomolecules such as hemoglobin (Hb) can be controlled-released from the hybrid material TiO2–DB–Hb by switching visible light on/off. The released Hb not only retains its senior structure but also can fulfil the enzymatic bioactivity. Controlled delivery of Hb stems from the scission of the Ti–O coordination bond with the aid of photo-inducing electron transfer property of titania.

A simple green process based on thermal condensation is developed to synthesize polyimide. The obtained product possesses a high degree of crystallinity and exhibits efficient photocatalytic activity for hydrogen production from water under visible light.

A monolayer MoS2 quantum dot confined polyimide (MQDs/PI) photocatalyst was synthesized by using a facile immersion-hydrothermal method. The investigations on the optical and electronic properties of MQDs/PI composites reveal that the strong quantum confinement effect of MQDs results in a blue-shift of the absorption band edge of PI, and the interfacial electronic interaction between MQDs and PI improves the charge transfer rate of MQDs/PI. The ultra-small size of 3.0 nm and perfect crystals of MQDs endow MQDs/PI composites with plenty of active sites and fast charge transfer, thus resulting in a 360% enhancement in photocatalytic hydrogen production compared with that of Pt/PI at the same loading amount of Pt. This discovery provides a new clue for the development of an efficient and sustainable non-noble metal photocatalyst.