ABSTRACT
In this study, a series of highly crystalline π-conjugated polyimide photocatalysts with porous nano hollow shell (HSPI) was prepared for the first time by the hard template method by adjusting the addition ratio of the template precursor. SiO2 nanospheres not only serve as template agents but also as dispersants to make precursors of SPI more uniform, and the degree of polymerization will be better, resulting in significantly enhanced crystallinity of HSPI relative to bulk SPI (BSPI). More strikingly, it is found that HSPI has a larger specific surface area, stronger visible light absorption, and higher separation efficiency of photogenerated electron and hole pairs compared with BSPI by various spectral means characterization analysis. These favorable factors significantly enhanced the photocatalytic degradation of methyl orange (MO) by HSPI. This work provides a promising approach for the preparation of cheap, efficient, environmentally friendly, and sustainable photocatalysts.
ABSTRACT
A novel two-dimensional graphene oxide/sulfur-doped polyimide (GO/SPI) hybrid polymer photocatalyst was synthesized by a facile ultrasonic chemical method. The characterization results showed that the skeleton structure of SPI was not changed when the few layers of GO were wrapped on the surface. Due to the excellent charge transport characteristics of GO and the strong π-π stacking interaction between two-dimensional GO and SPI, the photogenerated carrier transport capability of the GO/SPI composites was significantly enhanced compared with that of SPI. The efficient transmission and separation of photogenerated charge carriers significantly improve the photocatalytic degradation of the methyl orange activity of the GO/SPI composite. This work provides a facile and new way for the synthesis of metal-free inorganic-organic composite photocatalysts with high efficiency and low cost.
ABSTRACT
Efficient utilization of solar energy for photocatalytic hydrogen production and degradation of organic pollutants is one of the most promising approaches to solve the energy shortage and environmental pollution. A series of Co3O4/sulfur-doped polyimide (CO/SPI) direct Z-scheme nano-heterostructure photocatalysts was successfully prepared via a facile green thermal treatment method. The effects of Co3O4 nanoparticles on the structure, morphology, and optoelectronic properties of CO/SPI composite samples were systematically characterized by different spectroscopic methods. Characterization results confirmed that Co3O4 nanoparticles as an acid oxide catalyst promoted the oxidation stripping of bulk SPI to form SPI ultrathin nanosheets. Thus, the Co3O4 nanoparticles were firmly embedded on SPI ultrathin nanosheets to construct a direct Z-type CO/SPI nanostructure junction. Therefore, the activity and cycle stability of photocatalytic water splitting for hydrogen production and organic pollutant degradation were greatly improved under solar light irradiation. In particular, the 0.5CO/SPI composite sample displayed the highest activity with an average production rate of 127.2 µmol g-1 h-1, which is nearly 13 times and 106 times higher than that of SPI and Co3O4. This work provides a new avenue for constructing efficient inorganic-organic nanoheterostructured Z-type photocatalysts and takes an important step towards the efficient utilization of renewable energy.
ABSTRACT
In this study, a novel direct Z-scheme SnS2 quantum dots/sulfur-doped polyimide (SQDs/SPI) photocatalyst was firstly fabricated by an in situ crystallization growth of SnS2 quantum dots on sulfur-doped polyimide through a facile hydrothermal method. The photocatalytic hydrogen production activity of 5SQDs/SPI samples reached 3526 µmoL g-1 in the coexistence of triethanolamine and methanol used as hole sacrificial agents, which is about 13 times higher than that of SPI under the same conditions and 42 times higher than that of SPI only as a hole sacrificial agent. The improvement can be related to the direct Z-scheme charge transfer in the tight interface between SQDs and SPI, which promoted rapid separation and significantly prolonged the lifetime of photoexcited carriers. The Z-scheme charge transfer mechanism was proposed. This discovery comes up with a new strategy for the development of an efficient, environmentally friendly, and sustainable sulfide quantum dots/polymer non-noble metal photocatalyst.
ABSTRACT
A novel two-dimensional α-Fe2O3/sulfur-doped polyimide (FO/SPI) direct Z-scheme photocatalyst was successfully constructed by a facile thermal treatment method. The effects of α-Fe2O3 nanosheets on the morphology, chemical structure, and photoelectronic properties of FO/SPI composites were systematically characterized by different spectroscopic means. These methods include X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, transient fluorescence spectra, and so forth. It was confirmed that the small amounts of α-Fe2O3 can availably facilitate exfoliation of bulk SPI, resulting in a transformation of SPI from bulk to 2D layered composite that illustrates tight interface through the coordination Fe-N bond and an all-solid-state direct Z-scheme junction. Thus, the transfer and separation efficiency of photogenerated electron/hole pairs were significantly enhanced, which greatly promoted improvement of the photocatalytic activity of the FO/SPI composite for methyl orange degradation under solar light. This work provides a new approach to constructing efficient inorganic-organic Z-scheme photocatalyst based on strong interface interaction.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Inconspicuous penis is a group of symptoms that can make penis body not be showed normally instead of a kind of simple disease. They are presented with conclude concealed penis, buried penis, webbed penis and trapped penis. Most of them are resulting from congenital abnormality except the trapped penis. The diminutive penis caused by hypospadia and intersex and micropenis resulted from endocrine disease does not belong to this category. Pathological changes of concealed penis, buried penis and webbed penis are congenital but trapped penis is caused by acquired reasons. It's not difficult to make the diagnosis by the pathological and clinical manifestations. According to different age's indication, type and severity of the disease, corresponding surgery method ought to be chosen and the curative effect can be obtained.
