Novel 2D Zn-porphyrin metal organic frameworks revived CdS for photocatalysis of hydrogen production

The main challenge of photocatalysis is how to improve the coefficient of utilization and conversion rate for solar energy. Herein, we report a composite photocatalyst related to a novel porphyrin metal organic frameworks (MOFs), in which cadmium sulfide nanoparticles (CdS NPs) are grown in situ on the surface of two-dimensional (2D) zinc porphyrin nanosheets (Zn-TCPP NSs) by hydrothermal method. Interestingly, Zn-TCPP NSs and CdS NPs form a Type II heterojunction structure, which reduces the photogenerated electron-hole recombination rate of CdS. Moreover, in the near-infrared region, the photo-excited electrons generated by Zn-TCPP NSs are transmitted to CdS NPs, so that cadmium sulfide can realize both visible light and near-infrared light for photocatalytic hydrogen production. The Zn-TCPP NSs not only has excellent light absorption capacity, but also has a unique frame design that effectively reduces the recombination rate of photoinduced electron hole pairs, thus improving the conversion rate of solar energy. As expected, the photocatalytic performance of the porphyrin MOFs modified materials is significantly enhanced compared to CdS NPs. The hydrogen production rate of the Pt@CdS NPs/Zn-TCPP NSs(C-Z-T) composite material in the visible light region is about 15.3 mmol g^?1 h^?1, which is 11 times for Pt@CdS NPs. Furthermore, the Pt@CdS NPs/Zn-TCPP NSs(C-Z-T) also has a considerable hydrogen production rate in the near-infrared region, such as 200 μmol g^?1 h^?1 at 600 nm, 90 μmol g^?1 h^?1 at 765 nm and 20 μmol g^?1 h^?1 at > 800 nm.     

Electrocatalytic hydrogen evolution of highly dispersed Pt/NC nanoparticles derived from porphyrin MOFs under acidic and alkaline medium

Platinum (Pt)-based electrocatalysts often exhibit an excellent electrocatalytic activity for hydrogen evolution due to their best hydrogen bonding energy, but materials with high Pt content can easily cause aggregation and reduce their efficiency. In this article, Pt-based electrocatalysts with uniform dispersion and high efficiency were fabricated by a successive hydrothermal and calcination method, and the uniformly distributed Pt nanoparticle was mainly due to the anchoring effect of porphyrin ring in porphyrin MOFs, which made the minimized agglomerations as much as possible in the process of high temperature calcination. The results showed that the optimal Pt/NC-850 could reach current density of 10, 50 and 100 mA cm^?2 with only 17, 82 and 152 mV overpotentials, while the Pt/NC-850 also exhibited a superior stability and durability under acidic medium. Impressively, the Pt/NC-850 also had an excellent activity, good stability and durability under alkaline medium.     

Continuous gas–liquid aerobic oxidation of toluene catalyzed by [T(p-Cl)PPFe]2O in a series of three stirred tank reactors

The liquid-phase catalytic aerobic oxidation of toluene by [T(p-Cl)PPFe]₂O was studied in a series of three stirred tank reactors. The effects of operation mode (including semi-batch and continuous operation), reaction temperature, catalyst concentration, average residence time, and air flow rate on the oxidation process were examined. The experimental results showed that continuous oxidation had no advantage over the total yield and selectivity of benzaldehyde and benzyl alcohol in comparison with semi-batch oxidation. And the reaction temperature was the most significant factor influencing on continuous oxidation of toluene. It is also found that adopting sequentially decreased temperature in the three series reactors could improve the yield and selectivity of benzaldehyde and benzyl alcohol in this process. Under which at the higher conversion of toluene, the total yield to benzaldehyde and benzyl alcohol increased 17.05% or 43.62% respectively in comparison with adopting sequentially increased or same temperature in the three series reactors.     

Electrospun Poly(acrylonitrile-co-acrylic acid) Nanofibrous Membranes for Catalase Immobilization:Effect of Porphyrin Filling on the Enzyme Activity

Porphyrin-filled nanofibrous membranes were facilely prepared by electrospinning of the mixtures of poly(acryionitrile-co-acrylie acid)(PANCAA) and porphyrins. 5,10,15,20-Tetraphenyiporphyrin(TPP) and its metalloderivatives(ZnTPP and CuTPP) were studied as filling mediators for the immobilization of redox enzyme. Results indicate that the introduction of TPP, ZnTPP and CuTPP improves the retention activity of the immobilized catalase.Among these three porphyrins, the ZnTPP-filled PANCAA nanofibrous membrane exhibits an activity retention of93%, which is an exciting improvement. This improvement is attributed to both the strong catalase-porphyrin affinity and the possible facilitated electron transfer induced by the porphyrin as evidenced by quartz crystal microbalance (QCM) and fluorescence spectroscopy studies.     

Porphyrin-functionalized gold nanoparticles for selective electrochemical detection of peroxyacetic acid

Two layers of cationic iron(III) meso-tetrakis (N-methylpyridinum-4-yl)porphyrin (FeTMPyP) and anionic gold nanoparticles (GNPs) were alternately assembled on a poly(diallyldimethylammonium chloride)-wrapped carbon nanotube (PDDA-CNT)-modified electrode via electrostatic interactions. The porphyrin-functionalized gold nanoparticles were characterized by scanning electron microscopy and UV–vis absorption spectrometry. The (FeTMPyP–GNP)₂/PDDA-CNT modified electrode showed two stable and well-defined peaks at −0.112 V and −0.154 V, which were attributed to the GNP-accelerated redox process of Fe(III)TMPyP/Fe(II)TMPyP. The modified electrode possessed excellent electrocatalytic behavior for the reduction of peroxyacetic acid (PAA). The resulting biosensor exhibited a fast amperometric response to PAA (∼3 s), with a wide linear range from 2.5 × 10⁻⁶ M to 1.05 × 10⁻³ M and a detection limit of 0.5 μM at a signal-to-noise ratio of 3. More importantly, H₂O₂ did not interfere with the detection. Thus, this biosensor enabled highly sensitive detection of PAA without removing H₂O₂ and showed a promising potential in practical applications.     

Effects of structures of pyrolyzed corrin,corrole and porphyrin on oxygen reduction reaction

The effects of the structures of various pyrolyzed cobalt-based macrocyclic compounds, which are pyrolyzed cobalt-corrin compounds (py-Co-Corrin/C), pyrolyzed cobalt-corrole compounds (py-Co-Corrole/C) and pyrolyzed cobalt-porphyrin compounds (py-Co-Porphyrin/C), on their activities in the oxygen reduction reaction (ORR) are studied. Following the pyrolysis, py-Co-Corrin/C has a higher ORR activity than py-Co-Corrole/C and py-Co-Porphyrin/C, which their electron-transfer numbers are 3.90, 3.87 and 3.37 at 0.3 V, respectively. According to the analysis of near edge X-ray absorption fine structure in N K-edge, only py-Co-Corrin/C has the Co–N₄ chelate and poly-aromatic hydrocarbons when pyrolyzed at high temperature. The X-ray absorption spectra reveal the oxidation states of central cobalt in cobalt-based macrocyclic compounds which are changed from high to low. Also, the atomic distances of cobalt to its neighbors vary among all of the samples. The experimental results suggest that the structure and the coordination of cobalt-based macrocyclic compounds strongly affect their ORR activities.     

Porphyrin-grafted cellulose fabric: New photobactericidal material obtained by “Click-Chemistry” reaction

A new antibacterial material has been elaborated by grafting mesoarylporphyrin on cotton fabric by the means of cellulose azidation followed by “Click-Chemistry” reaction with acetylenic porphyrin. Azidation and functionalization have been checked by ATR-FTIR spectroscopy. Under irradiation with visible light, this material displayed an antibacterial activity against representative strains of Escherichia coli and Staphylococcus aureus. This new photobactericidal textile has potential for industrial, medical, and household applications.     

Microstructures and photovoltaic properties of C60 based solar cells with copper oxides,CuInS2, phthalocyanines,porphyrin, PVK,nanodiamond, germanium and exciton diffusion blocking layers

Abstract

Organic solar cells have a potential for use in lightweight, flexible, inexpensive and large scale solar cells. However, significant improvements of photovoltaic efficiencies are mandatory for use in future solar power plants. One of the improvements is donor–acceptor proximity in the devices, which are called bulk heterojunction solar cells. Bulk heterojunction is an efficient method to generate free charge carriers, and the charge transfer is possible at the semiconductor interface. The purpose of the present work is to fabricate and characterise C₆₀ based solar cells with copper oxides, CuInS₂, phthalocyanines, porphyrin, poly-vinylcarbazole, nanodiamond, germanium and exciton diffusion blocking layers. In the present work, C₆₀ and fullerenol [C₆₀(OH)_10–12] were used for n-type semiconductors, and metal copper oxides, metal phthalocyanine derivative, porphyrin and poly-vinylcarbazole were used for p-type semiconductors. In addition, nanodiamond and germanium based molecules were added into the active layers of the solar cells. The novel aspect of the research is to investigate the relation between properties and microstructures of the solar cells using transmission electron microscopy, X-ray diffraction and electronic structure calculation. The impact of the research concerns the study of organic solar cells by means of microstructural analysis, property measurements and theoretical calculations.     

Investigation of self-assembled dendrimer complexes

Dendrimer complexes[(G-2)₄P and (G-3)₄P]with a porphyrin core have been prepared by self-assembling of sodium tetrakis(4-sulfonatophenyl) porphyrin with dendritic quaternary bromides (G-2 and G-3), which were synthesized by reaction of Frechet type dendritic bromides (G-2 and G-3) with triethylamine. The structure of dendrimer complexes was confirmed by ¹H NMR and element analysis. The stoichiometry rate between the dendritic quaternary bromide and porphyrin core was 4:1. Solvatochromism studies of the dendritic complexes showed that the (G-3)₄P dendritic complex is more stable than the (G-2)₄P dendritic complex. It is inferred that hydrophobic interactions play an important role in stabilizing these dendrimer complexes in addition to coulombic interactions.