Carbon Composite Photocatalyst Research Articles

Preparation of TiO2-graphitized carbon composite photocatalyst and their degradation properties for tetracycline antibiotics

To enhance the adsorption capacity to tetracycline antibiotics and the activity of TiO2 for photocatalysis and optical applications, modified graphitized carbon (GC) was fabricated by peanut shell and waste electrode graphite materials. Then graphitized carbon-doped TiO2 (TiO2-GC) was synthesized using the impregnation method. Characterization of structure and morphological were confirmed that the crystal structure of the TiO2 film on the GC was pure anatase phase. FTIR and XPS peaks clearly indicated the formation of the Ti-C-O valence bond, and the UV–vis DRS showed that the bandgap of TiO2 decreased to 2.67 eV. Electrochemical properties indicated the excellent photoelectric properties and the recombination rate of photogenerated electron-hole pairs became lower in the composite photocatalyst. The results of the photocatalytic degradation of tetracycline hydrochloride experiment showed that the composite photocatalyst had high adsorption and degradation ability for tetracycline (catalysts amount 0.7 g/L, 94.64% with visible lamp irradiation for 2 h) and the photodegradation process accorded with the first-order kinetic equation. TiO2-GC remained stable in five consecutive cycles, which proved its reusability. Furthermore, its excellent cost-effectiveness and strong photon absorption property, which makes it a promising candidate for tetracycline antibiotics effluent treatment in practical applications.

Construction of Molybdenum Disulfide/Biological Structure Carbon Composite Photocatalysts and Their Photocatalytic Hydrogen Production

The hydrothermal calcination method using bamboo leaves as the biological template, thiourea as the sulfur source, and molybdenum chloride as the molybdenum source was employed to synthesize the molybdenum disulfide/biological structure carbon (MoS2/C) photocatalytic composites with different concentrations of molybdenum chloride. The thermal decomposition behavior, surface morphology, phase structure, BET specific surface area, optical and photoluminescence properties, and photocatalytic activity of MoS2/C photocatalytic composites with different concentrations of molybdenum chloride were studied. The results showed that the optimal temperature for synthesizing MoS2/C photocatalytic composites is 700°C. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations show that the hydrothermal calcination method can be used to load MoS2 onto the biological carbon and form a structurally stable composite system. Analysis of optical and photoluminescence properties shows that the MoS2/C composites prepared by the hydrothermal calcination method with the concentration of molybdenum chloride of 0.20 mol/L exhibit a high charge transfer and separation efficiency. Photocatalytic experiments show that the MoS2/C composites prepared by the hydrothermal calcination method with the concentration of molybdenum chloride of 0.20 mol/L have a high photocatalytic activity and cyclic stability. This excellent synthesis strategy can be used to synthesize other photocatalytic hydrogen production materials.

Modification of TiO2/AC catalyst for visible light degradation of ionic liquid contaminated wastewater: Effect of Cu loading on the characterization and efficiency

The emergence of ionic liquids (ILs) as a green substitute for the conventional volatile organic compound has attracted many researchers to keep synthesizing and improving ILs formula for enhanced performance in various industrial application. Due to the various possible combinations of cations and anions, the properties of the formulated ILs varies which directly affecting its toxicity and degradability. One of the major concerns over the use of ILs is the potential water pollution caused by cross contamination during the industrial processes. The present study reports on the photodegradation of 1-butyl-3-methylimidazolium chloride ([C 4 mim][Cl]), which is a common IL used in industry. The effect of Cu 2+ loading on the performance of TiO 2 /Activated carbon composite photocatalyst was studied. The modification of TiO 2 with Cu 2+ managed to shift the absorption edge of TiO 2 towards visible light region, with enhanced performance as compared to the pristine TiO 2 . Less agglomeration rate of the Cu-TiO 2 /AC in comparison to TiO 2 and TiO 2 /AC revealed the important role of metal dopant in suppressing the growth rate during the calcination process. The presence of activated carbon (AC) as support for the powdered TiO 2 has improved the diffusion rate of [C 4 mim][Cl]. The Cu-TiO 2 /AC composite photocatalyst containing 0.1 wt% of Cu showed the highest total degradation compared to other photocatalysts which is in agreement with the characterization analysis of the composite photocatalyst.

Enhanced photocatalytic activity of ternary g-C3N4/NaTaO3/biomass carbon composite photocatalysts under visible-light radiation

Highly efficient visible-light-responsive ternary graphitic carbon nitride (g-C3N4)/NaTaO3/biomass carbon (BM-C) photocatalysts with different g-C3N4 amounts were prepared via a solvothermal method combined with a high-temperature sintering method. Herein, the crystal structure and morphology of g-C3N4/NaTaO3/BM-C are investigated in detail. The light-response characteristics of g-C3N4/NaTaO3/BM-C composites are effectively extended into the visible-light region. Compared with NaTaO3/BM-C and g-C3N4/NaTaO3, the g-C3N4/NaTaO3/BM-C composite showed high visible-light catalytic performance when the mass ratio of melamine (the g-C3N4 precursor) to binary NaTaO3/BM-C is 4:1, and the degradation extent of 95.85% for Rhodamine B can be reached in 60 min under visible-light irradiation. In addition, the photocatalytic mechanism showed that the enhanced photocatalytic activity of the composite may be attributed to the introduction of g-C3N4, which expanded the visible-light response range and the formation and effect of a good synergistic effect of BM-C and various components. This work provides useful insights for promoting the practical process of sodium tantalate photocatalytic materials.

Cu2S-Cu-TiO2 mesoporous carbon composites for the degradation of high concentration of methyl orange under visible light

A Schiff base compound was used to prepare a Cu2S-Cu-TiO2 mesoporous carbon composite photocatalyst (Cu2S-Cu-TiO2/MC) by a simple precipitation-carbonization method with a carbonization temperature of 750°C. X-ray diffraction and x-ray photoelectron spectroscopy studies show that Cu2S, Cu, and TiO2 exist in Cu2S-Cu-TiO2/MC in the form of nanometer-sized particles. Scanning electron microscope and transmission electron microscope images show that the composites form a spherical carbon structure inlaid with Cu2S and Cu and coated TiO2. The Brunauer-Emmett-Teller test shows that the material has a large specific surface area (76.14m2/g) and mesoporous structure. UV–vis diffuse reflection spectroscopy and photoluminescence spectroscopy indicate that the recombination of photo-generated electrons and holes in the samples were inhibited. The composites show good degradation performance in a high concentration (300mg/L) of methyl orange (MO) solution under visible light. The composites exhibit great potential in the treatment of dyes for wastewater treatment.

Environmentally benign chitosan as precursor and reductant for synthesis of Ag/AgCl/N-doped carbon composite photocatalysts and their photocatalytic degradation performance

In this study, we reported a novel Ag/AgCl loaded N-doped carbon composite photocatalyst (Ag/AgCl/NC) which was fabricated by a facile and green method. The composite was prepared only by two simple steps. Firstly, the Ag/N-doped carbon (Ag/NC) was prepared by one-step hydrothermal treatment; during this progress the environmentally benign and renewable natural chitosan was used as not only reducer and stabilizer, but also as a nitrogen source and carbon source. Secondly, Ag/AgCl/NC composite was synthesized via in situ oxidation reaction by adding FeCl3. The Ag/AgCl/NC composite was characterized using X-ray diffraction, transmission electronic microscopy, energy dispersive X-ray spectra, UV-visible diffused reflectance spectra, X-ray photoelectron spectroscopy and nitrogen adsorption-desorption measurements, respectively. The obtained Ag/AgCl/NC composite exhibited a superior photocatalytic activity and stability for the degradation of rhodamine B (RhB) under visible light irradiation.

Silver carbonate loaded on activated carbon composite photocatalyst with enhanced photocatalytic activity under visible light irradiation

A composite photocatalyst based on silver carbonate (Ag2CO3) loaded on activated carbon (AC) was prepared by ion-exchange deposition method. The obtained photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), UV/Vis diffuse reflection spectroscopy (DRS), N2 adsorption–desorption measurements and transient photocurrent measurements. The removal efficiency of Ag2CO3/AC composite including adsorption and photodegradation was studied for degrading Rhodamine B (RhB) in aqueous solution under visible light irradiation. Compared with the pure Ag2CO3, the prepared composite catalyst has larger surface area and adsorption capacity of organic pollutants. It could be summarized that synergy of photodegradation and adsorption has a great improvement for the removal of RhB under visible light irradiation compared with that of only adsorption without light. A remarkable RhB removal efficiency of 96.6% was achieved by the prepared Ag2CO3/AC (20%) composite. The possible catalytic reaction mechanism of Ag2CO3/AC was also proposed.

Visible-light-driven inactivation of Escherichia coli K-12 using an Ag/AgCl–activated carbon composite photocatalyst

Abstract In this work, the inactivation of Escherichia coli K-12 was investigated using a novel Ag/AgCl–activated carbon composite photocatalyst under visible light irradiation. The photocatalyst was found to inactivate 97% of bacteria under irradiation for 60 min in a 5 g/L slurry. The composite also possessed some biocidal action due to the incorporated silver, however, the action of the photo-induced radical species on the bacteria seemed to dominate the inactivation process. The mechanism of photocatalysis-induced cell death was thought to be attributable to attack of radical species causing damage to the cell wall, and was probed by indirect observations of changes to cell membrane permeability and structure.

Hierarchically mesostructured TiO2/graphitic carbon composite as a new efficient photocatalyst for the reduction of CO2 under simulated solar irradiation

A hierarchically mesostructured TiO2/graphitic carbon composite photocatalyst with a high content of nanocrystalline TiO2 was prepared using a simple one-step nanocasting route. X-ray diffraction, thermogravimetric analysis, nitrogen adsorption–desorption, transmission electron microscopy and X-ray photoelectron spectroscopy were used to characterize this photocatalyst. It was observed that the coexistence of silica and graphitic carbon during the high temperature treatment stabilized the crystalline phase and the size of the anatase TiO2 nanocrystals (5–7 nm in diameter), which were uniformly dispersed in the graphitic carbon matrix after silica removal. The obtained hierarchically mesostructured TiO2/graphitic carbon composite photocatalyst with a high specific surface area and a high surface concentration of hydroxyl groups exhibited considerably higher activity in the photocatalytic reduction of CO2 with H2O under simulated solar irradiation compared to mesostructured anatase TiO2 prepared using a sol–gel method.

Kinetics of Photocatalytic Degradation of Gaseous Organic Compounds on Modified TiO2/AC Composite Photocatalyst

This study is focused on the kinetic characteristics of photocatalytic degradation of gaseous organic compounds on modified titanium dioxide/activated carbon composite photocatalyst (MTA). The MTA, which co-doping with iron (Fe) and nitrogen (N), was synthesized by a sol-gel method, and its photocatalytic performance was investigated under different reaction conditions. The experimental data obtained were tested by the zero, first and second order kinetic model, and the factors affecting the kinetic model were analyzed. It was clearly demonstrated that the experimental data of toluene and acetone on MTA fit quite well with second order kinetic model equation, but the experimental data of formaldehyde fits well with zero order kinetic model equation.

Microwave-Assisted Preparation of TiO2/Activated Carbon Composite Photocatalyst for Removal of Methanol in Humid Air Streams

TiO2/activated carbon composite photocatalyst was prepared by a microwave-assisted impregnation method and was employed for the removal of methanol from humid air streams. A commercial microwave oven (800 W) was used as the microwave source. Under 2450 MHz microwave irradiation, titanium tetra-isopropoxide (TTIP) was quickly hydrolyzed and anatase TiO2 was formed in a short time (<20 min). As a result of the volumetric heating and selective heating of the microwave, the solvent and byproducts were quickly removed which reduced energy consumption and processing time. The formed submicrometer TiO2 particles mainly deposited on the external surface of carbon. In a packed bed reactor with an empty bed contact time of 0.35 s, the prepared materials maintained a 40% removal efficiency at an inlet methanol concentration of 39 ppm. When the TTIP conversion was complete, neither the irradiation time nor the water/TTIP ratio could further change the photocatalytic activity.

Preparation of novel TiP 2O 7 carbon composite using ion-exchanged resin (C467) and evaluation for photocatalytic decomposition of 2-propanol

TiP 2O 7 carbon composite photocatalyst was successfully prepared by using ion-exchanged resin (C467) containing amino phosphate by metal ion-exchanged carbothermal reduction (MIER-CTR) method using TiCl 3 and TiCl 4. During the carbonization process in nitrogen, the pre-oxidation (300–350 °C) in air is essential for producing homogeneously dispersed TiP 2O 7 on the carbon matrix. In the absence of pre-oxidation, the resin was melted. The carbonization temperature 500 °C was found to be suitable for producing single phase TiP 2O 7 with higher yields. Powder X-ray diffraction (XRD) and Raman spectroscopic results suggest the formation of TiP 2O 7, while X-ray diffraction results reveal that the crystallite size was less than 35 nm. UV-Vis studies show that the band gap of TiP 2O 7 was 3.32 eV. The TiP 2O 7 carbon composite catalyst was applied for the photocatalytic decomposition of 2-propanol at 30 °C using a mercury lamp (365 nm).