Photocatalytic multiphase micro-droplet reactors based on complex coacervation

Spontaneous sequestration of TiO2 nanosheets within coacervate micro-droplets is used to prepare membrane-free liquid multiphase micro-reactors with photocatalytic activity.</p

Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity

Semiconductor TiO2 photocatalysis has attracted much attention due to its potential application in solving the problems of environmental pollution. In this paper, thiourea (CH4N2S) modified anatase TiO2 nanorods were fabricated by calcination of the mixture of TiO2 nanorods and thiourea at 600 °C for 2 h. It was found that only N element was doped into the lattice of TiO2 nanorods. With increasing the weight ratio of thiourea to TiO2 (R) from 0 to 8, the light-harvesting ability of the photocatalyst steady increases. Both the crystallization and photocatalytic activity of TiO2 nanorods increase first and then decrease with increase in R value, and R2 sample showed the highest crystallization and photocatalytic activity in degradation of Brilliant Red X3B (X3B) and Rhodamine B (RhB) dyes under visible light irradiation (λ &gt; 420 nm). The increased visible-light photocatalytic activity of the prepared N-doped TiO2 nanorods is due to the synergistic effects of the enhanced crystallization, improved light-harvesting ability and reduced recombination rate of photo-generated electron-hole pairs. Note that the enhanced visible photocatalytic activity of N-doped nanorods is not based on the scarification of their UV photocatalytic activity

Enhanced visible-light photo-oxidation of nitric oxide using bismuth-coupled graphitic carbon nitride composite heterostructures

Pure bismuth (Bi) metal-modified graphitic carbon nitride (g-C3N4) composites (Bi-CN) with a pomegranate-like structure were prepared by an in situ method. The Bi-CN composites were used as photocatalysts for the oxidation of nitric oxide (NO) under visible-light irradiation. The inclusion of pure Bi metal in the g-C3N4 layers markedly improved the light absorption of the Bi-CN composites from the ultraviolet to the near-infrared region because of the typical surface plasmon resonance of Bi metal. The separation and transfer of photogenerated charge carriers were greatly accelerated by the presence of built-in Mott-Schottky effects at the interface between Bi metal and g-C3N4. As a result, the Bi-CN composite photocatalysts exhibited considerably enhanced efficiency in the photocatalytic removal of NO compared with that of Bi metal or g-C3N4 alone. The pomegranate-like structure of the Bi-CN composites and an explanation for their improved photocatalytic activity were proposed. This work not only provides a design for highly efficient g-C3N4-based photocatalysts through modification with Bi metal, but also offers new insights into the mechanistic understanding of g-C3N4-based photocatalysis.(C) 2016, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved

Hollow Nanospheres Organized by Ultra-Small CuFe₂O₄/C Subunits with Efficient Photo-Fenton-like Performance for Antibiotic Degradation and Cr(VI) Reduction

Hollow transition metal oxides have important applications in the degradation of organic pollutants by a photo-Fenton-like process. Herein, uniform, highly dispersible hollow CuFe2O4/C nanospheres (denoted as CFO/C-PNSs) were prepared by a one-pot approach. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images verified that the CFO/C-PNS catalyst mainly presents hollow nanosphere morphology with a diameter of 250 ± 30 nm. Surprisingly, the photodegradation test results revealed that CFO/C-PNSs had an excellent photocatalytic performance in the elimination of various organic contaminants under visible light through the efficient Fenton catalytic process. Due to the unique hollow structure formed by the assembly of ultra-small CFO/C subunits, the catalyst exposes more reaction sites, improving its photocatalytic activity. More importantly, the resulting magnetically separable CFO/C-PNSs exhibited excellent stability. Finally, the possible photocatalytic reaction mechanism of the CFO/C-PNSs was proposed, which enables us to have a clearer understanding of the photo-Fenton mechanism. Through a series of characterization and analysis of degradation behavior of CFO/C-PNS samples over antibiotic degradation and Cr(VI) reduction, •OH radicals generated from H2O2 decomposition played an essential role in enhancing the reaction efficiency. The present work offered a convenient method to fabricate hollow transition metal oxides, which provided impetus for further development in environmental and energy applications. Highlights: Novel hollow CuFe2O4/C nanospheres were prepared by a facile and cost-effective method. CuFe2O4/C exhibited excellent photo-Fenton-like performance for antibiotic degradation. Outstanding photocatalytic performance was attributed to the specific hollow cavity-porous structure. A possible mechanism for H2O2 activation over hollow CuFe2O4/C nanospheres was detailed and discussed

Recent Advances of Doping and Surface Modifying Carbon Nitride with Characterization Techniques

As a non-metallic organic semiconductor photocatalyst, graphitic carbon nitride (g–C3N4, CN) has become a research hotspot due to its excellent performance in organic degradation, CO2 reduction and water splitting to produce hydrogen. However, the high recombination rate of electron-hole pairs, low specific surface area and weak light absorption of bulk CN synthesized by the traditional one-step thermal polymerization method seriously restrict its photocatalytic performance and practical application. To enhance the photocatalytic performance of CN, doping and surface modification strategies are usually employed to tune the band gap of carbon nitride and improve the separation of carriers. In this paper, the research progress of different methods to modify CN in recent years is introduced, and the mechanisms of improving the photocatalytic performance are mainly analyzed. Typical modification methods are mainly divided into metal doping, non-metal doping, co-doping and surface-functionalized modification. Some characterization methods that can analyze the doping state and surface modification are also discussed as examples. Finally, the difficulties that need to be addressed through modified CN photocatalysts and the directions for future research are pointed out

Assembly of CaIn2S4 on Defect-Rich BiOCl for Acceleration of Interfacial Charge Separation and Photocatalytic Phenol Degradation via S-Scheme Electron Transfer Mechanism

The novel 2D/2D S-scheme heterostructure of BiOCl nanosheets coupled with CaIn2S4 nanosheets (CaIn2S4/BiOCl-SOVs), which contains surface oxygen vacancies (SOVs), has been successfully prepared by high-temperature calcination combined with a solvothermal synthetic strategy. Under visible-light irradiation, the apparent rate constant (Kapp/mim−1) for phenol degradation on the 1 wt% CaIn2S4/BiOCl-SOVs photocatalyst is about 32.8 times higher than that of pure BiOCl. The superior performance was attributed to the synergistic effect between the SOVs, CaIn2S4, and BiOCl, which can effectively narrow the bandgap and accelerate the interfacial charge separation of CaIn2S4/BiOCl-SOVs heterojunctions. Subsequently, it significantly promotes the generation of superoxide radicals (O2−), hydroxyl radicals, and h+, which participate in the photodegradation process of phenol. The catalyst still maintained a relatively high activity after repeated tests as a demonstration of its photostability. This work successfully proposed an efficient method to design a new 2D/2D S-scheme heterostructure with SOVs as possible photocatalysts in the field of environmental remediation

Effects of fluorine on photocatalysis

\u3cp\u3eTailoring the microstructure of pristine TiO\u3csub\u3e2\u3c/sub\u3e is essential to narrow its band gap and prolong the charge lifetime. In particular, strategies involving fluorine have been used successfully to tune the surface chemistry, electronic structure, and morphology of TiO\u3csub\u3e2\u3c/sub\u3e photocatalysts to improve their photocatalytic activity based on the strong complexation between fluoride ions and TiO\u3csub\u3e2\u3c/sub\u3e and the high electronegativity of fluorine. In this review, we summarize the strategies involving fluorine to establish highly efficient TiO\u3csub\u3e2\u3c/sub\u3e photocatalytic systems or fabricate highly efficient TiO\u3csub\u3e2\u3c/sub\u3e photocatalysts. The main fluorine effects (i.e. the effects of fluorine on photocatalysis) include the following four aspects: (1) Surface effects of fluoride on TiO\u3csub\u3e2\u3c/sub\u3e photocatalysis, (2) effects of fluorine doping on TiO\u3csub\u3e2\u3c/sub\u3e photocatalysis, (3) fluoride-mediated tailoring of the morphology of TiO\u3csub\u3e2\u3c/sub\u3e photocatalysts, and (4) the effects of fluorine on non-TiO\u3csub\u3e2\u3c/sub\u3e photocatalysis. Additionally, the unique applications of these fluorine effects in photocatalysis, including selective degradation of pollutants, selective oxidation of chemicals, water-splitting to produce H\u3csub\u3e2\u3c/sub\u3e, reduction of CO\u3csub\u3e2\u3c/sub\u3e to produce solar fuels, and improvement of the thermostability of TiO\u3csub\u3e2\u3c/sub\u3e photocatalysts, are reviewed.\u3c/p\u3

Effects of fluorine on photocatalysis

Tailoring the microstructure of pristine TiO2 is essential to narrow its band gap and prolong the charge lifetime. In particular, strategies involving fluorine have been used successfully to tune the surface chemistry, electronic structure, and morphology of TiO2 photocatalysts to improve their photocatalytic activity based on the strong complexation between fluoride ions and TiO2 and the high electronegativity of fluorine. In this review, we summarize the strategies involving fluorine to establish highly efficient TiO2 photocatalytic systems or fabricate highly efficient TiO2 photocatalysts. The main fluorine effects (i.e. the effects of fluorine on photocatalysis) include the following four aspects: (1) Surface effects of fluoride on TiO2 photocatalysis, (2) effects of fluorine doping on TiO2 photocatalysis, (3) fluoride-mediated tailoring of the morphology of TiO2 photocatalysts, and (4) the effects of fluorine on non-TiO2 photocatalysis. Additionally, the unique applications of these fluorine effects in photocatalysis, including selective degradation of pollutants, selective oxidation of chemicals, water-splitting to produce H2, reduction of CO2 to produce solar fuels, and improvement of the thermostability of TiO2 photocatalysts, are reviewed

Boosting the Photoreactivity of g-C₃N₄ towards CO₂ Reduction by Polymerization of Dicyandiamide in Ammonium Chloride

As a typical organic semiconductor photocatalyst, graphitic carbon nitride (g-C3N4) suffers from low photocatalytic activity. In this paper, g-C3N4 was prepared by polymerization of dicyandiamide (C2H4N4) in the presence of ammonium chloride (NH4Cl). It was found that the addition of ammonium chloride can greatly improve the photocatalytic activity of g-C3N4 towards CO2 reduction. The optimal photocatalyst (CN-Cl 20) exhibited a CO2-to-CO conversion activity of 50.6 μmolg−1h−1, which is 3.1 times that of pristine bulk g-C3N4 (BCN) that was prepared in the absence of any ammonium chloride. The enhanced photoactivity of g-C3N4 was attributed to the combined effects of chloride modification and an enlarged specific surface area. Chloride modification of g-C3N4 can not only reduce the bandgap, but also causes a negatively shifted conduction band (CB) potential level, while ammonia (NH3) gas from the decomposition of NH4Cl can act as a gas template to exfoliate layered structure g-C3N4, improving the specific surface from 6.8 to 21.3 m2g−1. This study provides new ideas for the synthesis of highly efficient g-C3N4-based photocatalytic materials for CO2 conversion and utilization