Photocatalytic Activity Of Photocatalysts Research Articles

Interlinking the Fe doping concentration, optoelectronic properties, and photocatalytic performance of ZnO nanostructures

Doping is one of the effective strategies to modulate the optoelectronic properties and photocatalytic activity of photocatalysts. In this study, the effect of Fe doping (0–10 %) on morphology, optical and electronic properties, and photocatalytic activity of ZnO nanostructures is studied. The X-ray diffraction analysis shows that >5 % Fe doping, ZnFe2O4 is segregated as a secondary phase. The crystalline size decreases from 50.8 nm to 21.4 nm and the micro-strain increases with increasing the Fe concentration. The Fe doping-induced electronic restructuring facilitates visible light absorption through the O 2p → Fe 3d transition and the suppression of charge recombination by efficiently trapping conduction band electrons. Density functional theory (DFT) calculations are employed to unravel the underlying electronic changes induced by Fe doping in ZnO. The formation of shallow donor levels below the conduction band originates from the Fe 3d state. Photoluminescence spectra of pristine and Fe-doped ZnO nanostructures show characteristic emission peaks at approximately 384 nm and 570 nm, indicating the recombination of free excitons and oxygen interstitial defects, respectively. The results of the photocatalytic activity tests confirm that the 1 % Fe-doped ZnO nanostructures can exhibit the highest efficiency compared to the heavily doped ZnO nanostructures. The high efficiency in photocatalytic activity of 1 % Fe-doped ZnO nanostructures is ascribed to the modulated electronic structure and defect density. The adsorption affinity of methylene blue and water molecules to the surfaces of pristine and Fe-doped ZnO is simulated using the Monte-Carlo method. This study emphasizes the importance of controlling the dopant concentration to enhance the photocatalytic activity of various photocatalysts.

Photocatalytic degradation of 2,4-dichlorophenol using nanomaterials silver halide catalysts

In this study, the photocatalytic activity of nanomaterials Ag/AgX (X = Cl, Br, I) is reported. Highly efficient silver halide (Ag/AgX where X = Cl, Br, I) photocatalysts were synthesized through a hydrothermal method. The samples were characterized using a range of techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) to check their structural, morphology, textural and optical properties. In addition, the photocatalytic activity of photocatalysts was evaluated through the degradation of 2,4-dichlorophenol (2,4-DCP) under UV and visible light irradiation. XRD analysis confirmed the presence of a single-phase structure (pure phase) in the synthesized photocatalysts. SEM micrographs showed agglomeration with a non-uniform distribution of particles, which is a characteristic of surfactant-free precipitation reactions in aqueous media. The Ag/AgBr photocatalyst exhibited the best degradation efficiency, resulting in 83.37% and 89.39% photodegradation after 5 h of UV and visible light irradiation, respectively. The effect of catalyst loading, initial solution pH, and 2,4-DCP concentration was investigated for the best-performing Ag/AgBr photocatalyst. The degradation kinetics were best described by the pseudo-first-order Langmuir–Hinshelwood model. The photocatalytic capacity of Ag/AgBr decreased by 50% after five reuse cycles. SEM images revealed heightened levels of photodegradation on the catalyst surface. The study proved the feasibility of using simple synthesis methods to produce visible light active photocatalysts capable of degrading refractory phenolic pollutants in aqueous systems.

Understanding the effect of morphological change on photocatalytic activity of ZnO nanostructures and reaction mechanism by molecular dynamics

The photocatalytic activity of photocatalysts is often influenced by their particle morphology, dimension, size, exposed facets, porosity, etc. This work aims at gaining insights into the influence of the particle morphology of ZnO nanostructures on their photocatalytic activity. Under hydrothermal conditions, the Zn(NO3)2∙6 H2O:KOH (Zn:KOH) ratio is changed to 1:2, 1:8, and 1:12 to modulate the morphology of ZnO nanostructures. Particularly, the ZnO nanostructures with a nanostar-like morphology, synthesized at the Zn:KOH ratio of 1:8, exhibit the highest photocatalytic activity in comparison to ZnO nanoparticles and nanorods synthesized at the Zn:KOH ratios of 1:2 and 1:12, respectively. The enhanced photocatalytic activity for the degradation of methylene blue (MB) of ZnO nanostructures with a nanostar-like morphology is due to the presence of a large number of oxygen vacancy-related defects, which are preferably formed on the (1 0 1) facet of ZnO. The results from X-ray diffraction and photoluminescence spectroscopy analyses confirm it. Further, molecular dynamics (MD) simulation is involved to explore the interaction of oxygen atoms (as a representative of hydroxyl radical) with methylene blue molecules to understand the mechanism of enhanced MB degradation at the atomic level. The results of the computational study indicate the formation of hydroxyl radicals and the cleavage and the formation of some bonds in the side and central aromatic rings of MB molecules, which ultimately leads to the degradation of MB. Our findings reveal that it is important to control the morphology and facets of nanostructures for achieving high efficiency in the photocatalytic processes to be applied in practical application.

The role and effect of CdS-based TiO2 photocatalysts enhanced with a wetness impregnation method for efficient photocatalytic glucose electrooxidation

The 0.1% CdS-based TiO2photocatalysts with different atomic ratios were synthesized by the wetness impregnation (WI) method. These photocatalysts were characterized to actively determine surface area using TPx analyses (TPR, TPO, and TPD). Furthermore, surface structures and properties of photocatalysts were defined by analyses such as XRD, UV–VIS spectroscopy, SEM-EDX and mapping, fluorescence spectroscopy, TEM-EDS, and XPS. The photocatalytic activities of photocatalysts were examined by CV, CA, and EIS electrochemical analyses to investigate use in photocatalytic fuel cells (PFCs) in glucose solution in the dark and under UV illumination. The characterization analyses revealed that anatase TiO2 formed in the catalyst and its electronic structure and surface properties changed when doped with metal. The photocatalytic glucose electrooxidation (PGE) results indicated that the 0.1% CdS(50-50)/TiO2 catalyst exhibited much higher photocatalytic activity, stability, and resistance than other catalysts both in the dark (5.21 mA/cm2) and under UV illumination (16.21 mA/cm2). The study offers a promising new type of photocatalyst for PFC applications.

Direct Z-scheme Ag2WO4/BiOCl composite photocatalyst for efficient photocatalytic degradations of dissolved organic impurities

In this work, Ag2WO4/BiOCl composite photocatalyst was successfully prepared by a facile coprecipitation. The crystalline structures, morphologies, optical properties and photocatalytic activities of photocatalysts have been investigated via XRD, SEM, EDX spectrum, UV–vis diffuse reflectance spectroscopy, PL spectra and electrochemical measurement. After depositing Ag2WO4 onto the surface of BiOCl, its phase transformed from α-Ag2WO4 to β-Ag2WO4 and its morphology changed from nanorods to nanoparticles. Ag2WO4 nanoparticles easily grew and assembled on the surface of flower-like BiOCl nanosheets because of its large surface area, which remarkably promote more light scattering/reflection to broaden light absorption. The Ag2WO4/BiOCl Z-scheme heterojunction shows higher photocatalytic activity towards degradation of Rhodamine B (RhB) than that of pure BiOCl, the best photocatalytic efficiency is achieved by the10% Ag2WO4/ BiOCl heterojunction (81.3%) far surpasses that of pure BiOCl (52.1%) within 25 min under stimulated solar irradiation, owing to effectively improved charge separation of the photogenerated electron-hole pairs. The possible charge transfer processes and mechanism for photocatalytic degradation were proposed.

Metal-doped perovskite BiFeO3/rGO nanocomposites towards the degradation of acetaminophen in aqueous phase using plasma-photocatalytic hybrid technology

In this work, various BiFeO3 perovskite photocatalysts on reduced graphene oxide (rGO) were synthesized using three different gel agents of ethylene glycol (E), citric acid (C), and a combination of citric acid-ethylene glycol (CE). The phsyico-chemical properties of photocatalysts were characterized by XRD, FTIR, FESEM, BET-BJH, UV–Vis DRS, and VSM analyses. The photocatalytic activity of photocatalysts was tested towards the degradation of aqueous acetaminophen (APAP) in a non-thermal plasma reactor at ambient conditions. The results confirm that the highest APAP degradation rate of 90% is obtained by using plasma-photocatalytic oxidation in the presence of BiFeO3/rGO-CE nanocomposite while plasma alone shows a low degradation rate of 30%. To further improve the activity of BiFeO3/rGO-CE, it was doped using different metals like Mn, Zn, La, and Ba. It was confirmed that the APAP degradation rate increases to 98.6% using La-doped BiFeO3/rGO. Characterization analyses confirmed this sample had small nanoparticles with an average diameter of 5–6 nm. The highest BET surface area of 31.79 m2/g and the highest pore volume of 7.31 m3/g was obtained as well. Moreover, the La-doped BiFeO3/rGO showed the highest saturation magnetization of 5.2 emu/g that facilitate the separation of spent catalyst from treated wastewater.

Highly efficient visible light active Cu-ZnO/S-g-C3N4 nanocomposites for efficient photocatalytic degradation of organic pollutants.

The photocatalytic activity of photocatalysts is severely hampered by limited visible light harvesting and unwanted fast recombination of photogenerated e− and h+. In the current study, the photocatalytic efficiency of Cu–ZnO/S-g-C3N4 (CZS) nanocomposites was investigated against MB dye. The composite materials were designed via chemical co-precipitation method and characterised by important analytical techniques. Distinctive heterojunctions developed between S-g-C3N4 and Cu–ZnO in the CZS composite were revealed by TEM. The synthesized composites exhibit a huge number of active sites, a large surface area, a smaller size and better visible light absorption. The considerable enhancement in the photocatalytic activity of CZS nanocomposites might be accredited to the decay in the e–h pair recombination rate and a red shift in the visible region, as observed by PL and optical analysis, respectively. Furthermore, the metal (Cu) doping into the S-g-C3N4/ZnO matrix created exemplary interfaces between ZnO and S-g-C3N4, and maximized the photocatalytic activity of CZS nanocomposites. In particular, CZS nanocomposites synthesized by integrating 25% S-g-C3N4 with 4% Cu–ZnO (CZS-25 NCs) exhibited the 100% photocatalytic degradation of MB in 60 minutes under sunlight irradiation. After six cycles, the photocatalytic stability of CZS-25 NCs was excellent. Likewise, a plausible MB degradation mechanism is proposed over CZS-25 NCs based on photoluminescence and reactive species scavenger test observation. The current research supports the design of novel composites for the photocatalytic disintegration of organic contaminants.

Preparation of high-performance α-Bi2O3 photocatalysts and their photocatalytic activity

In the present work, α-bismuth (III) oxide (α-Bi2O3) photocatalysts with a porous and nanosheet structure were prepared by using the biomimetic-synthesis-assisted hydrothermal method. l-Arginine (C6H14N4O2) was used as the biomimetic template, and the pH value range of the precursor solution was 3–12. The as-obtained samples were characterized by X-ray diffraction, field-emission scanning electron microscopy and ultraviolet–visible diffuse reflectance spectroscopy. The photocatalytic activity of photocatalysts was evaluated by using rhodamine B (RhB; C28H31ClN2O3), tetracycline hydrochloride (TC-HCl; C22H24N2O8·HCl) and methyl orange (MO) as the targeted degradants under visible light irradiation. The results show that α-bismuth (III) oxide exhibits a high photocatalytic activity when the pH value of the precursor is 3 and the l-arginine content is 0.03 mol/l. Under the co-catalysis of hydrogen peroxide (H2O2), the degradation efficiencies of RhB, TC-HCl and MO are 75.3, 68.1 and 63.8%, respectively. The degradation rate of α-bismuth (III) oxide as prepared by using l-arginine for RhB degradation is about 2·09 times faster than that of template-free α-bismuth (III) oxide. The high photocatalytic activity is mainly attributed to the porous structure and high visible light response range of the α-bismuth (III) oxide photocatalyst.

Catalytic Conversion of Synthetic Sulfur-Pollutants in Petroleum Fractions Under Different Photocatalyst Loadings and Initial Concentration

In the oil and gas industry which applied to petroleum sources, thiophene is one of the sulphur contaminants that may harm the environment. The contents of sulphur in petroleum product gives out concern regarding the negative and harmful effect of sulphur contaminants onto environment and living health. One of the promising methods to degrade thiophene is photocatalytic degradation process. The usage of ZnO nanoparticles in photocatalytic degradation process has been wider due to its broad band gap, greater excitation of energy binding, and high stability. Several studies have discovered the ability of ZnO with capping agent in photocatalytic activity. Photocatalytic activity of photo-catalyst was affected by particle size, shape and morphology that are depending on the preparation method. Hence, this study put on priori-ties on synthesizing ZnO nanoparticles using precipitation method with the addition of KCC-1 which act as capping agent and used in the degradation of synthetic thiophene solution. The characterization of ZnO-KCC-1 using FTIR has confirmed that the successfulness produc-tion of ZnO-KCC-1 via precipitation method. There are three different loading of ZnO-KCC-1 (0.05 g/L, 0.10 g/L and 0.15 g/L) and thio-phene concentration (100 ppm, 300 ppm and 600 ppm) had been carried out in photocatalytic degradation of thiophene. The pH value for all fixed condition remains constant at natural pH range which is pH 7. The optimum condition of degrading synthetic thiophene under natural pH range by using ZnO-KCC-1 is at its loading of 0.05 g/L with the initial concentration of synthetic thiophene of 300ppm.The kinetic study of this research has been confirmed to be at the first-order of kinetic reaction.

Atomic defects in ultra-thin mesoporous TiO2 enhance photocatalytic hydrogen evolution from water splitting

Defects engineering is a promising and versatile method to improve solar-light-driven photocatalytic activity of photocatalysts. Mesoporous materials possess a versatile defective structure as well as a large exposed surface, which are particularly important in photocatalysis. Still, the underlying impact of defects in mesoporous photocatalysts remains elusive, as limited studies detail the exact atomistic surface structure and how the concentration of defects is directly related to the photocatalytic activity. Here, we successfully synthesized ultra-thin mesoporous-structured anatase TiO2 and changed the overall concentration of defects by improving the crystallinity. Without Pt deposition, the highest H2 production of ~3.507 mmol h−1g−1 was obtained under simulated solar light. We interrogated the atomic structure using scanning transmission electron microscopy, which directly revealed the coexistence of the lattice distortions and point defects in the mesoporous TiO2. Improving the crystallinity in TiO2 reduced these defects and slightly enhanced the H2 yield from water splitting, while the charge-transfer resistance increased. Further introduction of Ti3+ atomic defects decreased the charge-transfer resistance and facilitated the separation of electron-hole pairs in the photocatalysis. This study offers inspiration for designing efficient photocatalysts and provides valuable insights towards defect engineering in photocatalysts.

Enhanced visible-light photocatalytic activity of Ag/In2S3 photocatalysts induced by Schottky contact and SPR of Ag

In this work, a highly photocatalytic Ag/In2S3 was synthesized via the hydrothermal and photoreduction method. The as-prepared photocatalysts were confirmed by XRD, SEM, HRTEM, and XPS showing that Ag nanoparticles were decorated on the In2S3 surface. Photocatalytic activities of photocatalysts were investigated for photodegradation of methyl orange (MO) under visible light. The Ag/In2S3 composites showed the enhanced photocatalytic efficiency of 97% under visible light irradiation for 90 min, which was about 3.0 times higher than that of pure In2S3. The enhanced photocatalytic performance could be owing to the SPR of Ag and the Schottky junction formed between Ag and In2S3. Our PL results indicate the inhibited recombination of the photogenerated electron–hole pairs in In2S3 upon the attachment of Ag nanoparticles. The active species tests demonstrate that the superoxide radical (·O2−) and h+ are responsible for the efficient degradation of MO over Ag/In2S3. In addition, it also proposes a potential mechanism for enhancing the photocatalytic activity.

Constructing a novel hierarchical β-Ag2MoO4/BiVO4 photocatalyst with Z-scheme heterojunction utilizing Ag as an electron mediator

A novel β-Ag2MoO4/BiVO4 heterojunction photocatalyst was synthesized via a simple precipitation method. The photocatalytic activity of photocatalysts was assessed by RhB (Rhodamine B) and TC (tetracycline hydrochloride) degradation. Furthermore, the Ag nanoparticles were produced during the photocatalytic degradation process facilitates the construction of Z-scheme system. The XRD, XPS, SEM, EDX, TEM, HR-TEM and BET measurements revealed the structure and morphology properties and the UV–Vis DRS, PL, PT and EIS were used to investigate the optical properties. The results exhibited that the β-Ag2MoO4/BiVO4 heterojunction photocatalyst possess higher photocatalytic activity than individual BiVO4 and β-Ag2MoO4. Furthermore, h+ was the most crucial active species in the β-Ag2MoO4/Ag/BiVO4 Z-scheme system according to the reactive species trapping experiments. The potential Z-scheme photocatalytic mechanism also was discussed based on experimental and characterization results. This work shows a simple method to construct Z-scheme heterojunction photocatalyst by self-assembly and demonstrates that photocatalytic technology has great application prospects for water purification.

Enhanced visible-light photocatalytic activity of one dimensional In2O3/In2TiO5 nanobelts

In this study, a two-step synthesis route combining an electrospinning with a precipitation process was used to prepare one dimensional In2O3/In2TiO5 nanobelts. The obtained In2O3/In2TiO5 nanobelts were characterized with XRD, SEM, EDS, UV–vis DRS and N2 adsorption-desorption isotherms. Effects of the mole ratios of In2O3 to In2TiO5 on the photocatalytic activity of photocatalyst were investigated using rhodamine B (RhB) as a model pollutant. Results showed that In2O3/In2TiO5 nanobelts with the mole ratio of 1–10 exhibited the highest photocatalytic activity under xenon lamp (150 W) irradiation. The degradation rate of RhB reached 97.1% in 120 min, and the photocatalytic degradation followed the first order kinetic model. Furthermore, the skeleton of levofloxacin (LEV) was completely destroyed after irradiation for 60 min. The recycling tests confirmed that the photocatalytic activity was still above 85% after 5 cycles. This proved that In2O3/In2TiO5 not only had an excellent visible-light-driven photocatalytic activity, but also could be used in organic dye removal and antibiotics wastewater treatment.

Enhanced electron transport in rutile TiO2 nanowires via H2S-assisted incorporation of dissolved silicon for solar-driven water splitting

Si-doping is an effective approach to enhance the electron transport and the photocatalytic activity of photocatalyst. In this study, for the first time the silicate glass such as fluorine-doped tin oxide (FTO) glass substrate is used as the silicon source for preparing Si-doped TiO2 photoanodes. First, the rutile TiO2 nanowires (NWs) were grown on FTO glass substrates by hydrothermal reaction, accompanying with the gradual dissolution of glass to generate soluble Si dopant incorporated into TiO2 NWs. Second, the TiO2 NWs were reduced to form the Ti3+ by H2S reduction. Finally, the Si-doped TiO2 photoanodes with higher doping density was obtained by calcination. The visible photocatalytic activity of Si-doped TiO2 NWs photoanode towards water splitting increased about three times as compared with pure TiO2 NWs. Reduction by H2S resulted in the enhanced electron transport and massive increase in charge-carrier density. This work provides a novel paradigm for silicon doping in materials for accelerating their carrier transport and applications.

Decoration of SnO2 nanosheets by AgI nanoparticles driven visible light for norfloxacin degradation

Photocatalytic activity of photo-catalysts could be enhanced through many parameters. Along these parameters, segregation of the holes from the photo-generated electrons which could be considered an essential one. This issue could be attained via deposition of the co-catalysts over the surface of the semiconductor. In this investigation, the hydrothermal technique has been carried out to prepare nanosheets of SnO2. After that, SnO2 nanosheets were decorated by various contents of AgI nanoparticles (5–20%). the resultant AgI/SnO2 nanocomposites were subjected to photo-catalytic efficacy evaluation which were correlated with those of neat SnO2 as well as AgI for norfloxacin degradation upon Visible light irradiation. The obtained data proved that AgI nanoparticles content is considered an important aspect in improving the photo-catalytic efficiency of SnO2. It was shown that 15% AgI-dopant could be used as an optimum percent. Evidently, the photocatalytic efficiency of 15% AgI/SnO2 nano-composite was about 1.43 and 33.3 times larger than the photocatalytic efficiencies of pure AgI and SnO2, respectively. Moreover, AgI/SnO2 nanocomposite containing 15% AgI showed higher photocatalytic stability. The existence of AgI nanoparticles as cocatalyst may be the main explanation for the modification of the photo-catalytic efficiency of the AgI/SnO2 photo-catalyst. In fact, AgI nanoparticlaes facilitate adequate segregation of the charge carriers of SnO2 rather than the enlargement of the surface area and the decreasing of the band gap.

Extended light absorption and enhanced visible-light photocatalytic degradation capacity of phosphotungstate/polyimide photocatalyst based on intense interfacial interaction and alternate stacking structure

In previous research, phosphotungstic acid (H3PW12O40, PW)/polyimide (PI) composites were constructed using insoluble heptazine melem. We found that the introduction of PW can cause a slight increase in the light absorption of the composites. To further study the effects of polyoxometallate on the light absorption and photocatalytic activity of photocatalysts, a novel phosphotungstate/polyimide photocatalyst (MPWPI) was constructed via in situ solid-state thermal polymerization using melamine phosphotungstate ((C3N6H7)x[PW12O40], MPW) synthesized by water-soluble triazine melamine (C3H6N6, MA) and PW. The structural and morphological results confirm the successful construction and the alternate stacking structure of MPWPI. The alternate stacking structure is more favorable for the contact between polyoxometallate and polyimide, and it also facilitates the electron delocalization through the intermolecular phosphotungstate anions-π interactions. This will lead to the extended light absorption and enhanced visible-light photocatalytic degradation capacity. The UV–visible diffuse reflectance spectroscopy (UV–Vis DRS) results display that the light absorption of MPWPI can be obviously extended to 800 nm. Compared to the inactive polyimide and phosphotungstate, MPWPI exhibits extraordinary photocatalytic activity of imidacloprid under visible light irradiation (λ > 400 nm) for the extended light absorption and suppressed carriers recombination. For this photocatalytic system, the OH and O2− are the main active species. Furthermore, the encapsulated phosphotungstate anions in the specific structure of MPWPI give it excellent recyclability for the inhibited polar solvent dissolution.

One-pot solvothermal synthesis of carbon dots/Ag nanoparticles/TiO2 nanocomposites with enhanced photocatalytic performance

In this paper, we reported a “green” and facile method for one-pot solvothermal synthesis of carbon dots (CDs)/Ag nanoparticles (AgNPs)/titanium dioxide (TiO2, commercial Degussa P25) ternary nanocomposites with enhanced photocatalytic performance. The characterizations of this ternary photocatalyst were studied at length and our results revealed that the crystalline phase of TiO2 component remained unchanged after the reaction. While the newborn AgNPs and CDs were tightly attached onto the surface of TiO2 nanoparticles. The photocatalytic activities of photocatalysts were tested by measurements of photo-degradation on methylene blue (MB) under ultraviolet (UV) and visible light. It was showed that the photocatalytic performance of the ternary photocatalyst was superior to that of single TiO2 or CDs/TiO2 binary photocatalyst. It was probably attributed to the synergistic effect of the photoelectrical properties of CDs and the surface plasmon resonance (SPR) effect of AgNPs, which could both enhance the absorption of visible light and hinder the recombination of photogenerated electron-hole pairs.

Effect of Tin and Strontium Doping on the Photocatalytic Activity of Zinc Sulphide Nanoparticles for the Photocatalytic Degradation of Resorcinol under Solar and Ultra-Violet Light

Tin (Sn) and Strontium (Sr) doped Zinc Sulphide and pure Zinc Sulphide photocatalyst have been prepared by Sol-Gel method. The prepared photocatalyst have been characterised by Thermo gravimetric Differential Thermal Analysis, Scanning Electron Microscopy, Energy Dispersive X-ray, X-Ray Diffraction, ultra-violet visible spectroscopy and photoluminescence spectroscopy. Characterization Techniques have provided information of wurtzite hexagonal structure of Zinc Sulphide. The PL spectra have shown the blue shift of Zinc Sulphide after doping it with Tin and Strontium. Photocatalytic degradation study was done by the complete degradation of an organic pollutant Resorcinol in Sun light as well as in UV-light. The factors affecting the photocatalytic activity of photocatalyst viz. pH, catalyst loading and reuse of photocatalyst have been studied along with the photocatalytic degradation of Resorcinol. These external parameters have considerable influenced on the phtocatalytic activity of Zinc Sulphide.

ZnS/polyaniline composites with improved dispersing stability and high photocatalytic hydrogen production activity

Polyaniline (PANI)-ZnS composite photocatalysts with high photocatalytic hydrogen production activity were synthesized via a solvothermal method. Surface chemistry, crystalline property, optical property, surface morphology, surface area, photocurrent, and photocatalytic activity of the photocatalysts were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible diffuse reflectance spectroscopy, photoelectrochemical (PEC), BET, FTIR, and photocatalytic H2 production tests. Incorporation of the conductive polymer PANI can help the separation of photogenerated charge through the PANI-ZnS interfaces in the photocatalysis process and enhance the photocatalytic activity and stability of the PANI-ZnS photocatalysts. In addition, the dispersing stability of the composite photocatalysts in water was also improved. The P-ZnS-40 photocatalyst with 40 wt% PANI exhibits optimized photocatalytic H2 production rate of 6570 μmol h−1 g−1. After 3 cycles, the photocatalytic activity of the recycled photocatalyst remained at about 96% of its original activity for the first run.

Influence of heat treatment process on photocatalytic activity of photocatalyst TiO2/TiCxOy coatings during heat treatment in carbon powder

Photocatalyst TiO2/TiCxOy coatings on alumina (Al2O3) balls had been successfully fabricated by mechanical coating technique with titanium (Ti) powder and subsequent heat treatment in carbon powder. The influence of heat treatment conditions in carbon powder on the formed compounds, surface morphology and photocatalytic activity of photocatalyst TiO2/TiCxOy coatings was investigated. XRD results show that the compounds of TiCxOy and TiO2 were formed on the surface of Ti coatings during heat treatment in carbon powder. The relative amounts of TiCxOy and TiO2 remarkably varies with changing the heat treatment temperature and/or holding time. The formed nano-bump structure during heat treatment in carbon powder at 1073 or 1173 K, could increase the accessible surface area. The formation of Ti3+ and generated oxygen vacancies confirmed by XPS measurement, are in favor of narrowing band gap to enhance the visible-light photocatalytic activity of photocatalyst TiO2/TiCxOy coatings. The photocatalytic activity of the sample by heat treatment in carbon powder at 1173 K for 15 h shows highest. The fabrication strategy provides us a facile preparation procedure of visible-light responsive photocatalyst coatings.