A N and Fe codoped monoclinic BiVO4 (N–Fe-BVO) photocatalyst was prepared via a conventional sol–gel method and was evaluated for the photocatalytic reduction of CO2 with H2O under visible-light irradiation (>400 nm). As revealed by the structural and photoelectric characterization, the doped N and Fe species can enter the lattice of BiVO4 and induce the codopant levels in the forbidden region of BiVO4, which helps in increasing visible-light absorption, suppressing charge recombination and promoting charge migration. Compared to pure or single-doped BiVO4, the N–Fe-BVO photocatalyst exhibited substantially improved visible-light photocatalytic activity for CO2 reduction, with the highest hydrocarbon generation rate of 27 μmol h−1 gcat−1 and the corresponding quantum efficiency of 1.86% being obtained. The enhanced photocatalytic activity of N–Fe-BVO can be attributed to the synergistic effect of the simultaneous presence of the Fe and N dopants, and the possible photocatalytic mechanism was also proposed based on the characterization results.

We have developed a ratiometric sensor based on polyelectrolyte-induced pyrene excimers for the rapid and visual detection of heparin in aqueous media. This sensor has a simple preparation method, fast response, low cost, and high sensitivity and selectivity. As a complementary strategy for the detection of heparin based on the formation of pyrene excimers, this approach could identify heparin specifically over chondroitin sulphate, which is the major interferent in most sensing systems for the detection of heparin. The detection limit of this approach can be as low as 0.14 μM using fluorescence measurements. To the best of our knowledge, this is among the lowest LOD for the detection of heparin reported in the literature. It enables the rapid and visual detection of heparin both in buffered solution and serum samples.

The construction of a 3D graphene-based hybrid electrode with an optimized porous structure remains an attractive topic. Herein, we used the highly conductive graphene hydrogel (GH) with a well-defined 3D macroporous structure as a support to electrodeposite polyaniline (PANI), aimed to improve the energy density of GH-based capacitor electrode without deteriorating its high power capability. The as-prepared GH/PANI heterostructure with thin PANI layer conformally coated on the GH framework totally retains the native hydrogel pore structure and its high surface area, which facilitates the effective electron and ion transport within the electrode and thus endows GH/PANI composite electrode with excellent electrochemical properties such as a specific capacitance of 710 F g−1 at 2 A g−1 and 73% capacitance retention upon a current increase to 100 A g−1. Moreover, the assembled symmetric supercapacitor device based on GH/PANI heterostructure electrode delivers a maximum energy density and power density of 24 W h kg−1 and 30 kW kg−1, respectively, and also exhibits a good cycling stability with 86% capacitance retention after 1000 cycles. These findings demonstrate the importance and great potential of GH-based heterostructure in the development of high-performance energy-storage systems.

•Monolithic two-side Cu2O/graphene/TNA heterostructure photocatalyst was prepared.•CO2 photoreduction was achieved in a visible-light-driven dual-chamber reactor.•Methanol yield of 45 μmol cm−2 h−1 and quantum efficiency of 5.71% was attained.•The reaction mechanism and stability of the ternary heterostructure is explored.Efficient photocatalytic CO2 conversion to methanol under visible light irradiation (λ>400 nm) was achieved in a light-driven dual-chamber reactor using the monolithic two-side Cu2O/graphene/TiO2 nanotube array (TNA) heterostructure as separated oxidation and reduction catalyst, that was prepared with anodic TNA as the substrate following by sequential electrochemical deposition of graphene and Cu2O. The combined heterojunction in the ternary composite helps to improve the photocatalytic performance by increasing light absorption, preventing electron–hole recombination and facilitating electron transfer across the heterojunction interfaces, as revealed by photoelectrochemical measurements. Methanol generation rate of 45 μmol cm−2 h−1 was achieved, which is much higher than those obtained for existing TNA-based photocatalysts reported. Moreover, the quantum efficiency of 5.71% at 420 nm has been attained. The improved photocatalytic activity together with the proposed reaction mechanism demonstrated the advantage of Cu2O/graphene/TNA heterostructure and effectiveness of the reaction system, which can efficiently suppress charge recombination, improve interfacial charge transfer and inhibit the backward reaction by separating the photocatalytic reaction sites.Achieving efficient photocatalytic CO2 conversion to methanol in a visible-light-driven dual-chamber reactor with monolithic Cu2O/graphene/TNA heterostructure photocatalyst.

We report the synthesis of a simple pyrene derivative and its application in protamine detection and monitoring of trypsin activity. This assay can be conducted in aqueous solution and features rapid response, visual detection, high sensitivity and selectivity. The limit of detection of protamine was 0.5 μg mL−1. The IC50 value of a soybean trypsin inhibitor was estimated to be 0.51 U mL−1.

Graphitic carbon nitride (g-C3N4) nanosheets with large aspect ratios were fabricated from bulk g-C3N4 through an efficient top-down approach of moderate disintegration–exfoliation using diluted H2SO4 as an “efficient knife”. By prior disintegration in a diluted H2SO4 solution, the exfoliation of bulk g-C3N4 was effectively accelerated. The as-prepared g-C3N4 nanosheets possess a two-dimensional (2D) thin-layer structure with seven-atom thickness, a large lateral size of about 1 μm, and a high specific surface area of 80 m2 g−1. Compared with the bulk precursor, the g-C3N4 nanosheets showed much higher efficiency of photogenerated charge transfer and separation, and consequently exhibited enhanced photocatalytic activity toward hydrogen evolution and pollutant decomposition under both full-sunlight and visible-light irradiation.

Rapid and high-yield production of graphitic carbon nitride (g-C3N4) nanosheets was realized by simply adding water into a H2SO4 suspension of bulk g-C3N4, and the as-prepared nanosheets exhibit enhanced photocatalytic H2 evolution. Notably, the degree of exfoliation can be controlled by the amount of water to facilitate diverse applications of nano-sized g-C3N4.

•Nonvolatile rewritable memory effect in P3HT–graphene composite is demonstrated.•The memory device was fabricated through a simple solution processing technique.•The device shows a remarkable electrical bistable behavior and excellent stability.•Memory mechanism is deduced from the modeling of the currents in both states.An electrically bistable device utilizing a nanocomposite of hexadecylamine-functionalized graphene oxide (HDAGO) with poly(3-hexylthiophene) (P3HT) is demonstrated. The device has an ITO/P3HT-HDAGO/Al sandwich structure, in which the composite film of P3HT-HDAGO was prepared by simple solution phase mixing of the exfoliated HDAGO monolayers with P3HT matrix and a spin-coating method. The memory device exhibits typical bistable electrical switching behavior and a nonvolatile rewritable memory effect, with a turn-on voltage of about 1.5 V and an ON/OFF-state current ratio of 105. Under ambient conditions, both the ON and OFF states are stable under a constant voltage stress or a continuous pulse voltage stress at a read voltage of 1 V. The conduction mechanism is deduced from the modeling of the nature of currents in both states, and the electrical switching behavior can be attributed to the electric-field-induced charge transfer between P3HT and HDAGO nanosheets.

A novel series of triphenylamine-based photorefractive molecules M1–M5 with the different push-pull structures were designed and prepared. These molecules can form stable glasses with low glass transition temperature and their optical absorptions as well as photoconductivities at 633 nm increase systematically with increasing acceptor strength and conjugation length. As an unambiguous evidence, the two-beam-coupling experiment was performed to prove the photorefractive effect in each compound with or without an additional sensitizer. Obvious two-beam-coupling effects were obtained for the molecules with good film-forming ability and long-term stability, and among them single-component M1 which has a highly asymmetric structure using both a nitrobenzene and a cyano group as the acceptor showed the best PR performance with a gain coefficient of 52 cm−1 at 0 V μm−1 and 165 cm−1 at 40 V μm−1. Fast response time of 0.025–0.23 s were also obtained at low electric field for these glasses. The correlation of the molecular structure with the PR property was discussed, and a possible explanation for the unique energy transfer observed in M1 and M2 under zero field was proposed.Research highlights▶ A series of triphenylamine-based molecular glasses with low Tg and long-term stability were designed and prepared via simple reactions. ▶ Single-component M1 exhibited the better PR performance with a gain coefficient of 52 cm−1 (0 V μm−1) and 165 cm−1 (40 V μm−1). Fast response time of 0.025–0.23 s were obtained at low electric field for these glasses. ▶ The overall performances suggest that the present triphenylamine-based molecules are potentially good candidates for commercial application in organic photorefractive devices.

Graphitic carbon nitride (g-C3N4) nanosheets with large aspect ratios were fabricated from bulk g-C3N4 through an efficient top-down approach of moderate disintegration–exfoliation using diluted H2SO4 as an “efficient knife”. By prior disintegration in a diluted H2SO4 solution, the exfoliation of bulk g-C3N4 was effectively accelerated. The as-prepared g-C3N4 nanosheets possess a two-dimensional (2D) thin-layer structure with seven-atom thickness, a large lateral size of about 1 μm, and a high specific surface area of 80 m2 g−1. Compared with the bulk precursor, the g-C3N4 nanosheets showed much higher efficiency of photogenerated charge transfer and separation, and consequently exhibited enhanced photocatalytic activity toward hydrogen evolution and pollutant decomposition under both full-sunlight and visible-light irradiation.

We have developed a ratiometric sensor based on polyelectrolyte-induced pyrene excimers for the rapid and visual detection of heparin in aqueous media. This sensor has a simple preparation method, fast response, low cost, and high sensitivity and selectivity. As a complementary strategy for the detection of heparin based on the formation of pyrene excimers, this approach could identify heparin specifically over chondroitin sulphate, which is the major interferent in most sensing systems for the detection of heparin. The detection limit of this approach can be as low as 0.14 μM using fluorescence measurements. To the best of our knowledge, this is among the lowest LOD for the detection of heparin reported in the literature. It enables the rapid and visual detection of heparin both in buffered solution and serum samples.

We report the synthesis of a simple pyrene derivative and its application in protamine detection and monitoring of trypsin activity. This assay can be conducted in aqueous solution and features rapid response, visual detection, high sensitivity and selectivity. The limit of detection of protamine was 0.5 μg mL−1. The IC50 value of a soybean trypsin inhibitor was estimated to be 0.51 U mL−1.