Surface Area Of Photocatalyst Research Articles

Efficient photothermal catalytic CO2 reduction over in situ construction ZnIn2S4@Ni(OH)2/NiO Z-scheme heterojunction

Photocatalytic reduction of CO2 into valuable chemicals has been considered as a sustainable and environmentally friendly technology, which can simultaneously alleviate the energy crisis and environmental problems that have puzzled people for a long time. Herein, we successfully synthesize defective ZnIn2S4@Ni(OH)2/NiO (ZIS@NOH/NiO) Z-scheme heterojunction photocatalysts through solvothermal and low-temperature calcination strategies. The loading of Ni(OH)2 nanosheets can increase the specific surface area of photocatalyst, and form Z-scheme heterojunction with ZIS to improve the utilization of photogenerated electrons. It is worth noting that during the low-temperature calcination process, Ni(OH)2 is partially converted into NiO, and a large number of metal defects are formed, which reduces the bandgap of Ni(OH)2 and shows visible light response. In addition, the generated black defective NiO with full spectrum response and good photothermal effects can accelerate the migration of photogenerated carriers and reduce the catalytic reaction barrier of CO2. Consequently, the prepared ZIS@NOH/NiO exhibits a high yield (133.74 μmol g−1) and selectivity (86.2 %) for CO2 to CH4, which almost is 3.2 and 11.1 times than those of ZnIn2S4@Ni(OH)2 and ZnIn2S4, respectively. Furthermore, in-situ Fourier transform infrared spectroscopy (FTIR) analysis reveal the effective adsorption of CO2 on the ZnIn2S4@Ni(OH)2/NiO surface and the high selectivity of CH4. This work will provide meaningful prospects for designing a carbon dioxide reduction photocatalyst with high conversion and selective.

A Review on Impacting Parameters for Photocatalytic Degradation of Organic Effluents by Ferrites and Their Nanocomposites

Traditional wastewater treatment methods, such as reverse osmosis, adsorption, desalination, and others, are outweighed by the photocatalytic degradation of organic pollutants. Ferrites are prominent photocatalysts due to their tunable band gaps, surface areas, and magnetic properties, which render photodegradation economical. Ferrites and their nanocomposites have been reported as promising visible light active photocatalysts. The photocatalytic system is heavily reliant on a number of factors that influence the photodegradation of organic effluents. This review demonstrates various parameters such as substrate concentration, pH of solution, photocatalyst quantity, photocatalyst surface area, metal and non-metal ion doping, light intensity, irradiation time, quenchers, etc. affecting the photocatalytic degradation of organic effluents by ferrite nanoparticles and their nanocomposites in detail. The photodegradation efficiency of the ferrite nanoparticles alters with the change in the value of pH of the solution, which further depends upon the nature of the pollutant used. A dose of the substrate and the photocatalyst must be optimized so as to attain better photodegradation efficiency. Photocatalysts with different surface areas change the amount of active sites, which in turn affects the degradation of pollutant and render it a crucial factor. In addition, the mechanism of the action of photocatalysis is elaborated in this review. Future research perspectives for the advancement of ferrites and their nanocomposites are deliberated in order to improve their use as photocatalysts.

Fabrication of CdLa2S4@La(OH)3@Co3S4 Z-scheme heterojunctions with dense La, S-dual defects for robust photothermal assisted photocatalytic performance

Optimize the separation and transport mechanism of photogenerated carriers in heterojunction composites, and make full use of the active sites of each material are key factors to enhance photocatalytic activity. Herein, we successfully synthesize defective CdLa2S4@La(OH)3@Co3S4 (CLS@LOH@CS) Z-scheme heterojunction photocatalysts through a facile solvothermal method, which show broad-spectrum absorption and excellent photocatalytic activity. La(OH)3 nanosheets not only greatly increase the specific surface area of photocatalyst, but also can be coupled with CdLa2S4 (CLS) and form Z-scheme heterojunction by converting irradiation light. In addition, Co3S4 with photothermal properties is obtained by in-situ sulfurization method, which can release heat to improve the mobility of photogenerated carriers, and also be used as a cocatalyst for hydrogen production. Most importantly, the formation of Co3S4 leads to a large number of sulfur vacancy defects in CLS, and thus improving the separation efficiency of photogenerated electrons and holes, and increasing the catalytic active sites. Consequently, the maximum hydrogen production rate of CLS@LOH@CS heterojunctions can reach 26.4 mmol g-1h−1, which is 293 times than pristine CLS (0.09 mmol g-1h−1). This work will provide a new horizon for synthesizing high efficiency heterojunction photocatalysts through switching the separation and transport modes of photogenerated carrier.

Recent Development in Non-Metal-Doped Titanium Dioxide Photocatalysts for Different Dyes Degradation and the Study of Their Strategic Factors: A Review

Semiconductor titanium dioxide in its basic form or doped with metals and non-metals is being extensively used in wastewater treatment by photocatalysis due to its versatile nature. Other numerous characteristics including being environmentally friendly, non-pernicious, economical, multi-phase, highly hydrophilic, versatile physio-chemical features, chemical stability, suitable band gap, and corrosion-resistance, along with its low price make TiO2 the best candidate in the field of photocatalysis. Commercially, semiconductor and synthesized photocatalysts—which have been investigated for the last few decades owing to their wide band gap—and the doping of titania with p-block elements (non-metals) such as oxygen, sulfur, nitrogen, boron, carbon, phosphorus, and iodine enhances their photocatalytic efficiency under visible-light irradiation. This is because non-metals have a strong oxidizing ability. The key focus of this review is to discuss the various factors affecting the photocatalytic activity of non-metal-doped titania by decreasing its band gap. The working parameters discussed are the effect of pH, dyes concentration, photocatalyst’s size and structure, pollutants concentration and types, the surface area of photocatalysts, the effect of light intensity and irradiation time, catalyst loading, the effect of temperature, and doping impact, etc. The mechanism of the photocatalytic action of several non-metallic dopants of titanium dioxide and composites is a promising approach for the exploration of photocatalysis activity. The various selected synthesis methods for non-metallic-doped TiO2 have been reviewed in this study. Similarly, the effect of various conditions on the doping mode has been summarized in relation to several sorts of modified TiO2.

Alkaline mediated sono-synthesis of surface oxygen-vacancies-rich cerium oxide for efficient photocatalytic CO2 reduction to methanol

Photocatalytic CO2 reduction into desirable hydrocarbon products is one of the significant steps towards a sustainable ecosystem. Intriguingly, surface oxygen vacancies on pristine nanostructures enhance the effectiveness and selectivity of photocatalytic CO2 reduction. It is proposed here that cerium oxide nanostructure can be synthesized under ultrasound irradiation in an alkaline medium for rich surface defects. The acoustic bombardment of the ceria particles has resulted in turbulence generation and substantial impact during ultrasonic treatments, which energized the synthesis reaction for surface oxygen vacancies generation. Consequently, the ultrasonic treatment boosts the photocatalytic hydrogenation performance with excellent selectivity of methanol over CO. The final products had outstanding stability, and the smaller particle size increased the photocatalyst surface area. While the generated nanostructure was incredibly stable and reusable, the greater separation efficiency of the charge carriers due to surface imperfections is examined by the time-resolved photoluminescence spectra.

Decoration of ZnFe2O4 and UiO-66 over g-C3N4 as magnetically novel reusable visible light photocatalyst for degradation of Rh–B

In this research, a unique nanohybrid ternary g-C3N4/ZnFe2O4/UiO-66 (g-C3N4/ZnF/UiO) was successfully prepared applying a hydrothermal synthesis technique. The characteristic properties of the prepared nanocomposite were specified using different characterization methods such as FT-IR, XRD, EDX, SEM, TEM, VSM, GTA, DRS, and BET analysis. The use of zirconium-based (UiO-66) as metal-organic framework has resulted in an expansion in the total surface area of photocatalyst compared to the pure g-C3N4 sample, which has a significant effect on improving Rhodamine B (Rh–B) dye degradation. Maximum efficiency of photocatalytic achievement of the prepared g-C3N4/ZnF/UiO for photodegradation of Rh–B was obtained by using 10 wt% of UiO-66 expose to visible light irradiation for 60 min. The detailed analysis of the structural and degradation outcomes confirmed that the amended photocatalytic degradation performance could be credited to the extremely impressive spatial separation of the charge carriers between suggested materials. The results are also shown that the magnetic property of the synthesized nanocomposites to be enough and useful for separation and collection of the photocatalyst. The nanohybrid ternary can be good recyclability reused for sixth runs without apparent loss of its photocatalytic performance in degrading Rh–B pollutant. Consequently, the ternary g-C3N4/ZnFe2O4/UiO-66 (g-C3N4/ZnF-UiO) prepared nanocomposite can be a favorable replacement for the treatment of dye pollutants in wastewater.

Biosynthesis of highly porous Ag/Bi/SnO2 nanohybrid material using seeds extract of Caesalpinia bonduc and their photocatalytic activity

In the current study, Tin oxide (SnO2), Silver–Tin oxide (Ag–SnO2), and Ag–Bi–SnO2 nanoparticles (NPs) were successfully synthesized using methanolic seed extracts of Caesalpinia bonduc (C.bonduc) plants. The NPS were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Surface area analysis (SAA), energy dispersive X-ray (EDX) analysis, and Fourier transmission infrared (FTIR). The synthesized photocatalyst's surface area was 210, 235, and 238 m2/g for SnO2 and Ag–SnO2, and Ag–Bi–SnO2, respectively. The catalyst showed excellent activity for the degradation of MB dye in an aqueous medium. The results confirmed that the Ag–Bi–SnO2 exhibited 94% degradation of dye compared to Ag–SnO2 (90%) and SnO2(80%) under the same reaction conditions. Adding Ag and bismuth can also increase the degradation mechanism by preventing recombining electron-hole pairs. The report is novel, as no report to date has been published for the synthesis of Ag–Bi–SnO2, Ag–SnO2, and SnO2 NPs synthesized by C. bonduc seed extract; the procedure is simple, cheaper, and non-toxic compared to other methods employed for the synthesis of NPs. Eley-Rideal (ER) type of reaction mechanism was found to follow the degradation of MB dye in an aqueous medium.

Fabrication of Ag/ZnO@N-Carbon Core@Shell Photocatalyst for Efficient Photocatalytic Degradation of Rhodamine B.

Photocatalytic degradation method has been recognized as an effective way to eliminate the contamination of environment. However, developing photocatalysts with excellent photocatalytic properties are still a big challenge. In this paper, Ag doped ZnO coating with a layer of N doped porous carbon (Ag/ZnO@N-carbon) was successfully synthesized by using polyvinyl pyrrolidone (PVP) modified ZIF-8 as precursor via adsorption, hydrothermal treatment, in situ growth and carbonization processes. The physical and chemical properties of all samples were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), electron transmission microscopy (TEM) and so on. The results show that Ag doping does not change the crystallinity of ZnO, but broaden its photo-response property. The coating of N doped carbon can improve the specific surface area of photocatalyst. The photocatalytic activity of all samples was evaluated by degradation of rhodamine B (RhB) solution under UV light irradiation for 25 min. Ag/ZnO@N-carbon exhibits the highest photocatalytic activity for degradation of RhB with a degradation of 98.65%. Furthermore, Ag/ZnO@N-carbon also has high stability. Based on the characterization, possible mechanism for degradation of RhB by Ag/ZnO@N-carbon under UV light irradiation was proposed.

Preparation of separable MnFe2O4/ZnO/CQDs as a visible light photocatalyst for Gentamicin treatment

In the present study, we report a method for the preparation of magnetically separable, visible-light activated ZnO photocatalyst for wastewater treatment from pharmaceutical drugs. The photocatalyst consists of Manganese Ferrite core, coated with Zinc Oxide, doped with N,S-Carbon Quantum Dots. The photocatalyst was characterized by XRD, HR-TEM, FT-IR, VSM, BET adsorption, UV–Vis absorption, and Photoluminescence. FT-IR confirmed the presence of distinct bonds characteristics of the different components. VSM showed decrease in magnetization of MnFe2O4 in the composite but can still be attracted to a magnet. BET results showed the surface area of photocatalyst is 22.56 m2 g−1, and pore diameter is 3.1 nm. Interestingly, the absorption of Zinc Oxide was shifted from UV range toward visible range. A decrease of PL spectrum was observed due to the suppression of defects emission. Electrochemical tests revealed reduced charge transfer resistance of the composite compared to pristine ZnO. The photocatalytic activity was evaluated by degrading Gentamicin antibiotic. Experimental data showed that Gentamicin degradation reached 69.1% during 2 h of radiation for 250 mg/L of catalyst concentration, and degradation rate constant was 0.0082 min−1.

Photocatalytic degradation kinetics of cationic and anionic dyes using Au–ZnO nanorods: Role of pH for selective and simultaneous degradation of binary dye mixtures

Photocatalysis with ecofriendly and low cost materials is attractive for degradation of organic pollutants without aid of strong reagents. In this regard, Au nanoparticle decorated ZnO nanorods (Au–ZnO) with good crystalline quality was synthesized by cost-effective and scalable hydrothermal method followed by photo-reduction of Au salt. This study addresses variation of photocatalytic degradation kinetics of different nature of dyes with various scavengers and pH conditions. Further, the process versatility is demonstrated by selective or simultaneous degradation of binary dye mixtures with optimized parameters. From Langmuir-Hinshelwood kinetic model, dye concentration range for first order limiting case was determined, and further validated from measured surface area of photocatalyst and change in dye absorbance before irradiation. Better adsorption with faster degradation exhibited by Methylene Blue (MB) dye showed efficient mineralization, revealed from chemical oxygen demand measurements. In Au–ZnO photocatalysis, generation of hydroxyl radical and its significant role in dye degradation was demonstrated using different scavengers. Variation of dye adsorption with pH dependent surface charge characteristics of photocatalyst resulted about one order higher degradation rate constant of MB at high pH. Strong pH dependent MB degradation is shown to be useful for its selective or simultaneous degradation with other dyes. Results of this study are useful for designing photo-reactors and these nanoparticles are efficient for degradation of different dyes, their combinations and industrial effluents under low power UV lamp for treatment different organic pollutants.

Synthesis of novel eco-friendly CaO/C photocatalyst from coffee and eggshell wastes for dye degradation

For the first time, calcium oxide (CaO) and calcium oxide/carbon (CaO/C) are prepared by thermal decomposition from eggshell and coffee wastes as photocatalysts. The morphological, structural, chemical and optical properties of the prepared nanopowders were investigated using a variety of techniques. The crystallite size for plane (111) increases from 564.09 Å for CaO to 1654.67 Å for CaO/C, according to XRD. The CaO/C photocatalyst has a high increase in light absorption in the visible spectrum. The bandgaps of CaO and CaO/C are 1.73 and 1.52 eV, respectively. After 35 min of sunlight exposure, the photocatalytic removal of methylene blue (MB) dye employing CaO/C as a photocatalyst shown a significant improvement in removal (99.76 %) compared to CaO (88.04 %). The improvement is attributed to an increase in photocatalyst surface area and dye adsorption, which increases photocatalytic efficiency. The zero-, first-, and second-order kinetic parameters for CaO/C were investigated and discussed at various photocatalyst dosages. The current research can be used in the industry to remove toxic MB dye from wastewater and recycle coffee and eggshell wastes.

Enhanced photocatalytic degradation of Remazol Black under visible light illumination through S doped TiO2 (S-TiO2) nanoparticles: Operational factors and kinetic study

<p>The degradation of Remazol Black (RBB) by S-TiO2 photocatalyst was investigated. X-ray diffraction, fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and UV-vis specular reflectance spectroscopy has been used to characterize S-TiO2. The results suggested that the optical absorption edge of TiO2 was red-shifted by the addition of S dopants and the bandgap energy was 3.02 eV. The sulfur species were found to be evenly dispersed on the TiO2 crystal lattice as cationic sulfur (S6+) which corresponds to the cationic substitution on TiO2. The particle size decreased to 4-14 nm after S doping, which indicates that the addition of S dopants has contributed to an improvement in the photocatalyst surface area. The degradation of RBB was achieved 94% after 120 min visible light irradiation, a remarkable increase compared to bare TiO2 which was only able to degrade 48% of RBB at the same time. Optimization of the pH showed that the optimum pH for RBB degradation was 3.0, and the photocatalyst dose was 0.8 g L-1. Kinetic study showed that S-TiO2 photocatalytic degradation of RBB followed the pseudo-second-order kinetics model. Reducing the bandgap has been found to increase the activity of photodegradation in the visible light region.</p>

Pollutant photo-conversion strategy to produce hydrogen green fuel and valuable sulfur element using H2S feed and nanostructured alloy photocatalysts: Ni-dopant effect, energy diagram and photo-electrochemical characterization

Design and synthesis of effective, eco-friendly, low-price semiconductor-based photocatalyst/solar-energy materials and their application for photocatalytic transformation of plentiful/perilous hazardous chemicals (e.g. H2S) into hydrogen green fuel and other valuable elements is a promising/sustainable strategy, which is highly in demand from environmental, energy and fuel as well as chemical and technological standpoints. To this end, herein, a set of new quaternary, Ni-doped n-type solid-solution (alloy) semiconductor compounds, viz. NixIIFe0.2IIIZn0.7−xIIS (x=0, 0.02, 0.05 and 0.1) were synthesized through a facile one-pot hydrothermal route and employed for the photocatalytic conversion of alkaline H2S medium (pH=11) to hydrogen fuel and elemental sulfur. The investigations revealed that by adding Ni into the ternary photocatalyst-base (Fe0.2Zn0.7S), with decreasing the size of constituting nanoparticles and enlarging the photocatalyst surface area, the absorption intensity was strengthened. Among the materials under consideration, the lowest charge recombination (photoluminescence emission), highest photocurrent, and greatest displacement in open circuit and flat-band potentials were witnessed for x=0.05, the photocatalyst with maximum performance to produce H2 and S. Finally, by using photoelectrochemical data and depicting the energy-diagram of system, a detailed discussion was provided and the phenomenon was justified from physicochemical viewpoint.

Hierarchical TiO2 Nanoflower Photocatalysts with Remarkable Activity for Aqueous Methylene Blue Photo-Oxidation.

This study systematically evaluates the performance of a series of TiO2 nanoflower (TNF) photocatalysts for aqueous methylene blue photo-oxidation under UV irradiation. TNF nanoflowers were synthesized from Ti(IV) butoxide by a hydrothermal method and then calcined at different temperatures (T = 400–800 °C) for specific periods of time (t = 1–5 h). By varying the calcination conditions, TNF-T-t photocatalysts with diverse physicochemical properties and anatase/rutile ratios were obtained. Many of the TNF-T-1 photocatalysts demonstrated remarkable activity for aqueous methylene blue photo-oxidation at pH 6 under UV excitation (365 nm), with activities following the order TNF-700-1 > TNF-600-1 > TNF-500-1 > TNF-400-1 ∼ P25 TiO2 ≫ TNF-800-1. The activity of the TNF-700-1 photocatalyst (99% anatase, 1% rutile) was 2.3 times that of P25 TiO2 at pH 6 and 14.4 times that of P25 TiO2 at pH 4. Prolonged calcination of the TNFs at 700 °C proved detrimental to dye degradation performance due to excessive rutile formation, which reduced the photocatalyst surface area and suppressed OH• generation. The outstanding activities of TNF-700-1 and TNF-600-1 are attributed to their hierarchical nanoflower morphology which benefitted UV absorption, a near-ideal anatase crystallite size for efficient charge separation, and their unusually low isoelectric point (IEP = 4.3–4.5).

Probability Langmuir-Hinshelwood based CO2 photoreduction kinetic models

For engineering solutions, scaling photoreactors and processes, kinetic models that describe the impact of process conditions on CO2 photoreduction are critical to driving this technology forward. Probability Langmuir-Hinshelwood based CO2 photoreduction kinetic models were developed after several criteria that included: a high purity photodifferential photoreactor with a high ratio of reagent gas volume to irradiated photocatalyst surface area and automated robust data collection and kinetic modelling using a MATLAB program. Product distribution profiles indicated the dynamic changes occurring over the photocatalyst with an initial increase in H2 product distribution, followed by an increase in CH4 and finally CO product distribution, possibly due to the photocatalytic degradation of CH2O and CH2O2 intermediates. Production of H2 increased with a decrease in CH4 when the partial pressure of H2O was increased. Using the glyoxal mechanism, this is possibly explained via the formation of CH3CO2H from H2O reacting with CH3CHO that prevents the full conversion of CH3CHO to CH4. To account for deactivation, probability Langmuir–Hinshelwood based kinetic models were used to fit CO2 photoreduction kinetic data for CH4, CO and H2 with low average standard errors of 3.44×10-4,1.54×10-4 and 1.36×10-4, respectively. The probability LH based kinetic model coefficients were estimated with low standard deviations, using a robust and repeatable numerical method using a trust-region and multi-start algorithm. The models were used to predict optimised selectivity of CH4, CO and H2.

Wet chemical route synthesis of spinel oxide nano-catalysts for photocatalytic applications

Transition metal spinel type mixed oxides (FeCo2O4, MnCo2O4 and ZnCo2O4) nano-catalysts have been synthesized via co-precipitation route. The samples were characterized using XRD and FE-SEM techniques to determine structure and morphologies respectively. Furthermore, FTIR and BET analysis were carried out in order to confirm the structure and calculate surface areas of the samples. The photocatalytic potency of synthesized nano-catalysts have been examined for aqueous solution of methylene blue under visible light. It is found that photocatalytic activity of simple transition metal oxides was enhanced by making their binary/ternary metal oxides. FeCo2O4 exhibited highest photocatalytic efficiency among the prepared spinel structures while MnCo2O4 possess lowest efficiency. The photocatalytic behavior of mixed transition metal oxides can be accredited to its spinel structure, small particle size and large surface area. XRD and BET results revealed the small crystallite and particle size of spinel mixed oxides. The small crystallite size of spinel mixed oxides nano-structures contributes to increased photocatalytic activity by increasing the surface area of photocatalyst, decreasing the chance of reunion of charge carriers. It is observed that these binary oxide nano-structures have potential applications in heterogeneous photo decay of environmental contaminants and can act as propitious materials for resolving environmental issues and establishing green environment.

Photocatalytic membrane reactor performance towards oxytetracycline removal from synthetic and real matrices: Suspended vs immobilized TiO2-P25

Integrated hybrid systems coupling microfiltration (MF) with UVA photolysis (UVA-MF) or TiO2-P25 photocatalysis (UVA/TiO2-MF) were investigated for the removal of oxytetracycline (OTC) from synthetic (ultrapure water-UPW) and real (secondary effluent from an urban wastewater treatment plant-UWW) matrices, both spiked with 5 mg L−1 of OTC. The photocatalytic membrane reactor (PMR) was tested both using the TiO2-P25 nanoparticles in suspension or immobilized on the external surface of the membrane – nano-engineered membrane (NEM). In all cases, reaction occurs only inside the membrane module. The effect of transmembrane pressure (TMP) (1.0–2.0 bar) and of TiO2-P25 loading (0.1–0.4 g L–1) in slurry conditions, on the efficiency of the photocatalytic UVA/TiO2-MF system was investigated. Additionally, OTC oxidation efficiency was evaluated as a function of the amount of TiO2-P25 deposited on the external surface of the ceramic MF membrane. The membrane ensured the retention of TiO2-P25 particles, when using the PMR catalyst slurry system. The higher OTC removal efficiency (>90% of antibiotic removal after 30 min) as well as the higher permeate flux decline (66% after 5 h) were observed when using the highest TiO2-P25 loading. The NEM contributed to the in-situ OTC and by-products oxidation, improving its antifouling properties, and, consequently, leading to a low permeate flux decline (8% after 5 h) when using UPW as solution matrix. However, a permeate flux decline of 66% was observed for UWW-NEM after the same reaction time. Despite the advantages of NEM, the OTC removal efficiency was higher when using TiO2-P25 slurry due to the higher photocatalyst surface area. Nevertheless, the NEM showed a good stability of the catalyst thin film during 3 consecutive reaction cycles.

Preparation of MoS2@ZnO heterostructure with enhanced photocatalytic activity

In order to effectively solve environmental problems induced by organic pollutants, the MoS2@ZnO heterostructure is successfully fabricated via a two-step hydrothermal method, in which the MoS2 nanosheets grew on the surface of ZnO nanorods. The synthetic heterostructure is demonstrated to possess excellent photocatalytic activity in the degradation of methylene blue (MB) under ultraviolet (UV) and visible light irradiation. The corresponding photodegradation rate constant of MoS2@ZnO heterostructure reaches up to 0.02075 min−1 and 0.00916 min−1, which are higher than that of pure ZnO (0.00514 min−1 and 0.00048 min−1) under the same reaction conditions. Obviously, compared with pure ZnO, the photocatalytic activity of the MoS2@ZnO heterostructure has been significantly improved. This could be attributed to the increased specific surface area of photocatalyst and the formation of heterostructure between ZnO and MoS2 after loading the MoS2 on the surface of ZnO nanorods. Which help to provide more reaction sites for the adsorption of pollutant and improve the separation efficiency of photogenerated electron-hole pairs.

Developing Active TiO2 Nanorods by Examining the Influence of Morphological Changes from Nanorods to Nanoparticles on Photocatalytic Activity

We synthesized rutile TiO2 nanorods with high crystallinity, i.e., degree of crystallinity greater than ca. 90%, by using a hydrothermal method and studied the effect of the morphological change from rod shape to subsphere by the subsequent thermal treatment. The photocatalytic activity was estimated for O2 evolution from water oxidation because this reaction was hardly affected by the specific surface area of photocatalysts. Thermal desorption and gas chromatography–mass spectrometry measurements suggested the decomposition of residual glycolic acid in TiO2 nanorods at 272 and 590 °C. Observation with scanning electron microscopy and physical properties such as specific surface area and crystallite size indicated deformation of the rod shape to subsphere by the calcination above 600 °C. Time-resolved microwave conductivity measurements have revealed that the TiO2 nanorods possess the longest lifetime of photogenerated electrons among all samples. However, the O2 evolution rate of the TiO2 nanorods was mu...

Ammonia photosynthesis under ambient conditions using an efficient nanostructured FeS2/CNT solar-energy-material with water feedstock and nitrogen gas

Through a facile solvothermal route, pyrite (FeS2) semiconductor nanoparticles were synthesized in the absence and presence of carbon nanotube (CNT), and employed as effective, narrow-bandgap, hole-scavenger-free, photocatalyst/solar-energy materials in a water photosplitting setup, to convert N2 molecules into ammonia – a modern/green H-based fuel and agriculturally important chemical. The investigations revealed that the presence of CNT substantially enhances the photocatalyst activity. The superiority of FeS2/CNT nanocomposite energy material was explained in detail in terms of the ability of CNT to increase the photocatalyst surface area and interact with more N2 molecules, boost the absorption of photons and effectually harvest the incident light, retard the recombination of e/h pairs, decrease the system impedance and facilitate the charge transfer process. Based on water-oxidation and proton reduction phenomena occurring upon the photocatalyst surface, the N2-photofixation process was also interpreted from mechanistic/photoelectrochemical/energetic perspective.