Creation of passivated Nb/N p-n co-doped ZnO nanoparticles and their enhanced photocatalytic performance under visible light illumination

Passivated niobium/nitrogen (Nb-N) p-n co-doped zinc oxide nanoparticles were created by a simple precipitation process with in-situ self-formed NaCl “cage” to confine the nanoparticle growth followed by the heat treatment in a flow of ammonia gas. Enhanced optical absorbance into the visible light region was observed in the Nb/N co-doped ZnO nanoparticle photocatalyst due to the Nb/N co-doping effect. It demonstrated a largely enhanced photocatalytic performance in the disinfection of Escherichia coli bacteria under visible light illumination, which could be attributed to the passivated co-doping of Nb-N to suppress the photogenerated charge carrier recombination on dopants. This robust approach for passivated p-n co-doping may also be applied to other material systems for a wide range of technical applications.     

Mitochondria-targeting multi-metallic ZnCuO nanoparticles and IR780 for efficient photodynamic and photothermal cancer treatments

Chemo-resistance has pushed cancer treatment to the boundary of failure.This challenge has encouraged scientists to look for nanotechnological solutions.In this study,we have taken this goal one step further without depending on chemotherapy.Specifically,hybrid metal,polymer,and lipid nanoparticles that formed an IR780-a photosensitizer and Zinc copper oxide incorporated nanoparticle(ZCNP)nanoparti-cles were utilized in a combined photothermal and photodynamic therapy.Through the mediation of triphenylphosphonium(TPP)as a mitochondria-targeting moiety,TPP-conjugated polymer-lipid hybrid nanoparticles containing ZCNP/IR-780 significantly enhanced cellular uptake by cancer cells and selec-tively targeted the mitochondria,which improved the induction of apoptosis.In tumor-bearing mice,the nanoparticles were detected predominantly in tumors rather than in the other principle organs,which did not show notable signs of toxicity.Both in vitro and in vivo results demonstrated a great improvement in photothermal and photodynamic efficacy in combination when compared to either one individually,and a significant inhibition of tumor growth was observed with the combined therapies.In summary,this study describes an effective mitochondria-targeting nanocarrier for the treatment of cancer using combined photothermal and photodynamic therapies.     

Effect of Ag loading on activated carbon doped ZnO for bisphenol A degradation under visible light

Silver modified activated carbon doped zinc oxide (Ag/AC-ZnO) was synthesized via a calcination-electroless deposition route. The samples were characterized by X-ray powder diffractometry, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of the Ag/AC-ZnO was evaluated for bisphenol A degradation in the presence of H₂O₂ under visible light irradiation. The archived results showed that the photocatalytic activity of the Ag/AC-ZnO was higher than that of AC-ZnO and pure ZnO. The cytotoxicity of the bisphenol A after photocatalysis under visible light irradiation was tested using L929 mouse fibroblast cells and the obtained results indicated that the treated bisphenol A solution exhibited no cytotoxicity against normal cells.     

Effects of carbon on electrochemical performance of red phosphorus(P) and carbon composite as anode for sodium ion batteries

Red phosphorus/graphite(P/G) and red phosphorus/carbon nanotube(P/CNT) composites were prepared by ball milling red phosphorus with CNTs and graphite, respectively. The electrochemical results show superior electrochemical performances of the P/G and P/CNT composites compared with that of the reference sample milled with Super-P carbon. After 70 cycles, the P/G and P/CNT composites remained771.6 and 431.7 mA h g^-1, with 68 % and 50 % capacity retention, respectively. With increasing the milling time(20 h), CNTs were cut into short pieces and then broken into carbon rings and sheets which were well mixed with red phosphorus. The morphology of the P/CNT composite can buffer the large volume changes from alloying and de-alloying during cycling, resulting in the enhanced cycling stability.     

Photocatalytic degradation of Orange G on nitrogen-doped TiO2 catalysts under visible light and sunlight irradiation

In this paper, the degradation of an azo dye Orange G (OG) on nitrogen-doped TiO₂ photocatalysts has been investigated under visible light and sunlight irradiation. Under visible light irradiation, the doped TiO₂ nanocatalysts demonstrated higher activity than the commercial Dugussa P25 TiO₂, allowing more efficient utilization of solar light, while under sunlight, P25 showed higher photocatalytic activity. According to the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis spectra analyses, it was found that both the nanosized anatase structure and the appearance of new absorption band in the visible region caused by nitrogen doping were responsible for the significant enhancement of OG degradation under visible light. In addition, the photosensitized oxidation mechanism originated from OG itself was also considered contributing to the higher visible-light-induced degradation efficiency. The effect of the initial pH of the solution and the dosage of hydrogen peroxide under different light sources was also investigated. Under visible light and sunlight, the optimal solution pH was both 2.0, while the optimal dosage of H₂O₂ was 5.0 and 15.0 mmol/l, respectively.     

Thermo chemical stability of cadmium sulfide nanoparticles under intense pulsed light irradiation and high temperatures

Thermo chemical stability of CdS nanoparticles under an Intense Pulsed Light from a xenon flash lamp and high temperature X-ray Diffraction (XRD) were investigated. The CdS nanoparticles were obtained with a chemical bath method. The CdSO₄ (0.16 M) solution was added to an NH₃ (7.5 M) solution under constant stirring. Afterwards, a thiourea (0.6 M) solution was added. The bath temperature and pH were maintained at 65 °C and 10, respectively and the mixture was stirred constantly until a solid precipitate of yellow CdS was produced. Its microstructure was investigated with Scanning Electron Microscopy, and its electronic properties were determined by UV-visible and Photo luminescence Spectroscopy. The microstructure of the sintered CdS nanoparticles, obtained the high temperature XRD, was investigated with EDAX and X-ray micro Tomography. In addition, high temperature XRD and Themogravimetric Analysis tests were conducted over the samples. The CdS nanoparticles’ crystallinity increased with the irradiation exposure and they were thermally stable until 600 °C in argon atmosphere. However new phases start to appear after annealing at 400 °C for 30 min in air atmosphere. The main contribution of this paper was to investigate the stability of CdS nanoparticles under intense light and high temperature conditions. It was found that the number of irradiation shots conducted with the IPL technique increased the crystallinity of the CdS, by increasing the CdS nanopillars formation. A simple mechanism of ultra fast melting and cooling like quenching has been proposed to explain the phenomenon. It is also shown than at temperatures higher than 600 °C, different oxides appeared, while temperatures higher than 900 °C had a complete degradation of the CdS.     

Cu-BTC metal organic framework (MOF) derived Cu-doped TiO2 nanoparticles and their use as visible light active photocatalyst for the decomposition of ofloxacin (OFX) antibiotic and antibacterial activity

Herein, we report the ultrasonic-assisted precipitation technique for the fabrication of Cu-doped TiO₂ nanoparticles. The prepared sample showed high crystallinity, purity and nanoparticles like structure with the diameter in the range of 10–22 nm. The bandgap for Cu-doped TiO₂ nanoparticles was estimated to be 2.91 eV using Tauc plot, which is considerable for improving the light-harvesting capacity. Further, the prepared Cu-doped TiO₂ was used as photocatalyst for the eradication of ofloxacin (OFX), an antibiotic from an aqueous phase under visible illuminations. About 72% degradation of OFX (10 mg/L, pH 7) was achieved with Cu-doped TiO₂ nanoparticles after 180 min of visible illumination. The probable photocatalytic mechanism for the decomposition of OFX has been proposed based on reactive species trapping study. Moreover, the antibiotic efficiency of OFX was investigated against Escherichia coli and it was observed that its antimicrobial activity was significantly diminished after the photocatalytic decomposition of the OFX solution with synthesized nanoparticles.     

Novel application of g-C3N4/NaNbO3 composite for photocatalytic selective oxidation of biomass-derived HMF to FFCA under visible light irradiation

The g-C₃N₄/NaNbO₃ photocatalyst was synthesized by simply calcining the mixture of NaNbO₃ and melamine. The synthesized composite exhibits high photocatalytic performance in the selective oxidation of 5-Hydroxymethylfurfural (HMF) to 5-formyl-2-furancarboxylic acid (FFCA) when using water as solvent. The structure and composition of g-C₃N₄/NaNbO₃ photocatalysts were characterized by TG, XRD, SEM, UV–Vis, FT-IR, and XPS methods, and the optical and electrochemical properties were investigated by EIS, PC, and PL techniques. O₂⁻ was inferred to be the primary active species in this process based on the active species trapping experiment. Heterostructure formation of g-C₃N₄/NaNbO₃ composites efficiently promoted the separation of photo-generated electron-hole pairs and accelerated the electron transfer rate, thus reduced the formation of OH, and sequentially improved the selectivity of FFCA. The highest HMF conversion of 35.8% with FFCA selectivity of 87.4% was achieved on C/N-59.6 photocatalyst under the irradiation of visible light. The possible mechanism and reaction route were also proposed.     

Novel flower-like (Bi(Bi2S3)9I3)2/3 nanostructure as efficient photocatalyst for photocatalytic desulfurization of benzothiophene under visible light irradiation

Here, we report the preparation of hierarchical flower-like (Bi(Bi₂S₃)₉I₃)_2/3 nanostructures that acts as a strong photocatalyst in the desulfurization of benzothiophene. We optimized the reaction time, type of capping agent and reflux temperature to tune the shape of porous flower-like (Bi(Bi₂S₃)₉I₃)_2/3 nanostructures to achieve the highest desulfurization performance. We investigated the characteristic shape, size, purity, and optical response of the flower-shape nanostructures using XRD, EDS, FESEM, UV–Vis-DRS analysis. The flower-like (Bi(Bi₂S₃)₉I₃)_2/3 nanostructures showed a significant photocatalytic property in desulfurization of benzothiophene as a model fuel. The hierarchical flower-like (Bi(Bi₂S₃)₉I₃)_2/3 photocatalyst with an energy gap of 1.15 eV, exhibits a 92% photocatalytic desulfurization performance after 2 h of visible light irradiation. The (Bi(Bi₂S₃)₉I₃)_2/3 nanostructures show a high photocatalytic reproducibility after 4 rounds of exposure. We proposed a photo-oxidation mechanism based on the active species scavenging, which revealed the role of photo-produced h⁺ and O₂^? species as essential in the photocatalytic desulfurization process. These findings provide a new prospect and design strategy for the development of efficient photocatalysts in desulfurization process.     

Heat treatment of nanometer anatase powder and its photocatalytic activity for degradation of acid red B dye under visible light irradiation

The phase transformation of nanometer TiO₂ powder from anatase to rutile was realized by heat treatment, and a new nanometer TiO₂ photocatalyst that could be excited by visible light was obtained. The heat-treated TiO₂ powder at different transition stage was characterized by powder x-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The test of photocatalytic activity of the heat-treated TiO₂ powder was carried out by the photocatalytic degradation of acid red B dye in aqueous solution under visible light irradiation. The nanometer anatase TiO₂ heat-treated at 500°C for 30 min exhibited much higher activity than those of pure anatase and mechanically mixed (anatase and rutile) TiO₂. The remarkable improvement of photocatalytic activity was mainly illustrated by the special interphase between rutile and anatase, which not only restrains the recombination of photogenerated electron-hole pairs but also reduces the adsorbability of nanometer anatase TiO₂ powder to a certain extent. More significantly, the anticipatory interlaced energy level of heat-treated TiO₂ particles is convenient for capturing photons of low energy and thus achieves the intention of using visible light. The text was submitted by the authors in English.     

Combination of MoS2 nanopetals with Ag nanoparticles decorated graphene oxide for boosting photocatalytic abatement of recalcitrant pollutants under visible light irradiation

Herein, various weight ratios (1:1, 1:3, and 3:1) of MoS₂/GO composites decorated with Ag nanoparticles (named as MAG) have been prepared by microwave-assisted route. XRD and XPS investigations indicated the catalyst crystallinity and elemental oxidation states. Morphological analysis revealed presence of small MoS₂ nanopetals scattered on GO sheets with Ag NPs dispersed on surface whereas BET-analysis disclosed its excellent surface area (～88 m²/g). Optical properties of MAG catalysts revealed that they were highly visible-light active, with a bandgap of 2.15 eV and a lower charge recombination rate. Excellent efficiency was observed for TC (90.7%; 0.0186 min^?1) and FIP-degradation (85.2%; 0.0177 min^?1) with 4 mg MAG (3:1) catalyst at neutral pH under visible-light irradiation owing to high synergistic interaction (～2.21) in the composite. Effects of catalyst amount, pH, and effective area of illumination on degradation were investigated. High reusable nature of the catalyst (65% (TC) and 58% (FIP) efficiency after 5 cycles) was supported by post-photocatalytic characterization studies. Photodegradation products of TC were determined via LC-MS studies. Holes and hydroxyl radicals were majorly involved in degradation process revealed by trapping studies. High COD (70.4%) and TOC (55.1%) removal rates confirm high photo-mineralization of real-wastewater without any pre-treatment. The current investigation, combined with comparative literature, illustrates real-world potential of MAG catalysts for eradication of resistant pollutants.     

Fabrication of ultrafine ZnFe2O4 nanoparticles for efficient photocatalytic reduction CO2 under visible light illumination

A one-pot, solvent-thermal process was used to create the ultrafine ZnFe₂O₄ nanoparticles photocatalyst. During the solvent-thermal process, the in situ self-forming NaCl not only served as a “cage” to confine the ion diffusion, but also acted as a microreactor for nanocrystallite growth. An average particle size of ～10 nm and a high-specific surface area of ～112.9 m²/g were observed for the ultrafine ZnFe₂O₄ nanoparticles Owing to the synergistic effect of ultrafine particle size, the full utilization of the visible light region and high conduction band (CB) position, ultrafine ZnFe₂O₄ photocatalyst displayed an efficient photocatalytic CO₂ reduction under visible light illumination. Besides, the ultrafine ZnFe₂O₄ photocatalyst showed high production selectivity for CH₃CHO and C₂H₅OH generation in aqueous CO₂/NaHCO₃ solution. This work may provide a new idea for the synthesis of new high-efficiency photocatalysts.     

Integration g-C3N4 nanotubes and Sb2MoO6 nanoparticles: Impressive photoactivity for tetracycline degradation,Cr (VI) reduction,and organic dyes removals under visible light

The development of high-efficiency photocatalysts is an attractive strategy for pollutants degradation under visible light. Herein, novel photocatalysts are reported through coupling Sb₂MoO₆ with g-C₃N₄ nanotube (abbreviated as GCN nanotube) by a simple reflux method. Also, the nanocomposites were defined by applying various analyses. Under visible-light excitation, the GCN nanotube/Sb₂MoO₆ systems had more photoactivity than g-C₃N₄ (abbreviated as GCN) and the rate constant for RhB removal on optimal GCN nanotube/Sb₂MoO₆ (30%) nanocomposite was 48.3 times premier than the GCN. Also, compared to the pristine GCN, the GCN nanotube/Sb₂MoO₆ (30%) sample demonstrated supreme photoactivity towards tetracycline degradation and Cr (VI) photoreduction, which was 88.5 and 21.8 times higher than the bulk GCN, respectively. These impressive enhancements were attributed to the quick segregation of charge carriers, boosted visible-light absorption, and extended specific surface area. Moreover, the photocatalyst has enough activity after four successive cycles. Finally, a conceivable charges transfer route is presented through n-n heterojunction constructed between Sb₂MoO₆ and GCN nanotube.     

Facile synthesis of strontium molybdate coupled g-C3N4 composite for effective tetracycline and dyes degradation under visible light

This work was designed to synthesize SrMoO₄/g-C₃N₄ heterojunction for efficient degradation of tetracycline (TC) hydrochloride via photocatalysis. SrMoO₄/g-C₃N₄ samples were prepared through a grinding and roasting process. The prepared nanocomposite exhibited excellent visible-light-driven photocatalytic activity. The reaction rate of TC photodegradation reaches 0.0171 min^?1, which is 5.9 times higher than that of neat g-C₃N₄. The origin of the high photoactivity of SrMoO₄/g-C₃N₄ was investigated using a variety of characterization techniques including XRD, FT-IR, TG, SEM, TEM, XPS, DRS, Mott-Schottky, PL, PC, and EIS. Result showed that the added SrMoO₄ was closely loaded on the g-C₃N₄ surface, which is conducive to the electron transfer between SrMoO₄ and g-C₃N₄. Mott-Schottky analysis indicated that SrMoO₄ has a lower conduction band (CB) position than g-C₃N₄. As a result, photogenerated electrons in g-C₃N₄ can move to the CB of SrMoO₄ to hinder the recombination of charge carriers, thereby increasing the photocatalytic activity under visible light. The cycling test further suggested that the SrMoO₄/g-C₃N₄ heterojunction has good stability in the photocatalytic degradation of TC. Super oxygen radicals and holes are the main reactive species.     

海绵状Ag2O/ZnO复合光催化剂的制备及对甲醛的可见光降解

为克服纳米ZnO晶体可见光光催化活性低的缺点,以六水合硝酸锌、六亚甲基四胺和二水合草酸为原料,采用液相共沉淀-热分解法制备了六方纤锌矿型海绵状ZnO,然后在碱性条件下复合纳米Ag₂O颗粒,得到海绵状Ag₂O/ZnO复合光催化剂,并采用XRD、FTIR、紫外-可见漫反射（UV-Vis DRS）、FESEM、TEM和BET测量仪对其进行了表征;采用可见光光源,甲醛（HCHO）液体为光催化反应模型物,研究了不同摩尔比下Ag₂O/ZnO复合光催化剂的暗吸附及光催化性能。结果表明,随着Ag₂O相对含量的增加,HCHO暗吸附效果出现先增大后减小的趋势,当Ag₂O与ZnO摩尔比为1∶5时,HCHO去除率达到43.34%;另一方面,在可见光下Ag₂O/ZnO复合光催化剂对HCHO的降解率呈先增大后减小的趋势,其中Ag₂O与ZnO的摩尔比为1∶10时取得最佳降解效果,经过90 min的可见光光照后HCHO降解率达到78%,总的HCHO去除率为85%。      

BiOBr and BiOCl decorated on TiO2 QDs: Impressively increased photocatalytic performance for the degradation of pollutants under visible light

BiOBr and BiOCl were decorated on TiO₂ QDs through n-p-p heterojunctions by a simple strategy and they were applied for degradation of three organic dyes upon visible illumination. The obtained photocatalysts were analyzed via XRD, FESEM, EDX, UV–vis DRS, PL, BET, TEM, HRTEM, FT-IR, EIS, XPS, and transient photocurrent measurements. The TiO₂ QDs/BiOBr/BiOCl nanocomposite with 20% wt. of BiOBr and 30% wt. of BiOCl displayed superior photoability in the degradation of methylene blue, rhodamine B, and fuchsine, which was almost 34.5, 176, and 78.7-times larger than TiO₂ and 27.8, 13.5, and 51.5-folds greater than TiO₂ QDs, respectively. The results show that the construction of intimate n-p-p heterojunctions between BiOBr, TiO₂ QDs, and BiOCl counterparts leads to enhanced visible-light harvesting and improved charge separation, resulted efficiently increased photocatalytic activity. The trapping results proved that h⁺, ^•O₂⁻, and OH^• species have considerable effects on the degradation reaction. We think that the improved efficiency of the ternary TiO₂ QDS/BiOBr/BiOCl photocatalyst is a splendid alternative for the removal of toxic contaminants from wastewater.     

Preparation and characterization of ZnO-TiO2 nanocomposite for photocatalytic disinfection of bacteria and detoxification of cyanide under visible light

ZnO-TiO₂ nanocomposite was prepared by modified ammonia-evaporation-induced synthetic method. It was characterized by powder X-ray diffraction, transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray, UV-visible diffuse reflectance, photoluminescence and electrochemical impedance spectroscopies. Incorporation of ZnO leads to visible light absorption, larger charge transfer resistance and lower capacitance. The nanocomposite effectively catalyzes the inactivation of E. coli under visible light. Further, the prepared nanocomposite displays selective photocatalysis. While its photocatalytic efficiency to detoxify cyanide with visible light is higher than that of TiO₂ P25, its efficiency to degrade methylene blue, sunset yellow and rhodamine B dyes under UV-A light is less than that of TiO₂ P25.     

Relationship of structure and enhanced photocatalytic activity of S-scheme BiOCl/g-C3N4 heterojunction for xanthate removal under visible light

Constructing heterojunctions is an excellent way to enhance the photocatalytic property of semiconductors. Herein, a range of S-scheme BiOCl/g-C₃N₄ heterojunctions with varying mass ratios were designed using a facile hydrothermal route, and their photocatalytic ability was assessed by degrading the ethyl xanthate (EX) under visible light (λ > 400 nm). The results showed that the degradation efficiency of BiOCl/g-C₃N₄-0.1 heterojunction for EX was up to 91.2 % within 180 min, and its apparent rate constants (K_app) were 4.3 and 11 times greater than those of BiOCl and g-C₃N₄, respectively. The experimental and characterization results revealed that the excellent photocatalytic property was ascribed to the construction of S-scheme heterojunctions. Such structure not only enhanced the visible light response but also facilitated the efficient separation of photoinduced carriers with the S-scheme transfer route, retaining strong redox-capable holes and electrons to participate in surface reactions. Furthermore, the cycling experiments indicated that the fabricated photocatalysts have great recyclability and stability. Based on the results of active substance capture, the S-scheme charge transfer model was proposed and the photodegradation mechanism of EX was reasonably elucidated. Overall, this work offers some theoretical direction for the design and construction of S-scheme heterojunctions with superior visible-light-driven photocatalytic performance.     

Synthesis of Se nanoparticles by using TSA ion and its photocatalytic application for decolorization of cango red under UV irradiation

In this study, we describe a size-controlled synthesis of selenium nanoparticles based on the reduction of selenious acid (H₂SeO₃) by UV-irradiated tungstosilicate acid (H₄SiW₁₂O₄₀, TSA) solution which serves both as reducing reagent and stabilizer. The nanoparticles are characterized by ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), the Raman spectra, transmission electron microscopy (TEM) and Zetasizer, respectively. The characteristic catalytic behavior of the Se nanoparticles is established by studying the decolorization of cango red in the presence of UV light. It is obvious that selenium catalyzes the reaction efficiently. The results show that the rate of dye decolorization varies linearly with the nanoparticle concentration and the rate of dye decolorization decreases with the size of the Se nanoparticles increasing.     

复合光催化剂CdS-Pt/TiO_2低温制备及可见光制氢性能

用不同方法制备了CdS-Pt/TiO2复合光催化剂。催化剂通过X射线衍射、比表面和紫外-可见漫反射吸收进行了表征。以可见光光解水制氢为探针反应,考察了CdS-Pt/TiO2复合光催化剂的可见光活性。结果表明制备方法极大地影响CdS-Pt/TiO2复合光催化剂的活性。低结晶度的CdS与Pt/TiO2复合形成的CdS-Pt/TiO2复合光催化剂具有最高的可见光活性,其光解水的量子效率为6.95%。