Highly efficient In2S3/WO3 photocatalysts: Z-scheme photocatalytic mechanism for enhanced photocatalytic water pollutant degradation under visible light irradiation

A Z-scheme system In₂S₃/WO₃ heterojunction was fabricated via a mild hydrothermal method and further applied for photocatalytic degradation of tetracycline (TCH) and Rhodamine B (Rh B) under visible light irradiation. The morphological structure, chemical composition and optical properties were studied by XRD, SEM, HRTEM and UV-visible absorption spectra. The results revealed that In₂S₃/WO₃ hierarchical structures were successfully constructed, and the prepared In₂S₃/WO₃ photocatalysts exhibited enhanced visible-light absorption compared to pure WO₃ nanorods, which are essential to improve the photocatalytic performance. The degradation rate of TCH using the In₂S₃(40 wt%)/WO₃ heterostructure (WI40) photocatalyst was about 212 times and 22 times as high as that for pure WO₃ and pure In₂S₃, respectively. The degradation rate of Rh B with the WI40 photocatalyst was about 56 times the efficiency of pure WO₃ and 7.6 times that of pure In₂S₃. The results of the surface photovoltage (SPV), transient photovoltage (TPV) and reactive oxidation species (ROS) scavenger experiments indicated that the Z-scheme system of In₂S₃/WO₃ is favorable for photoexcited charge transfer at the contact interface of In₂S₃ and WO₃, which benefits the charge separation efficiency and depresses the recombination of photoexcited charge, resulting in favorable photocatalytic pollutant degradation efficiency under visible light irradiation.

A Z-scheme system In₂S₃/WO₃ heterojunction was fabricated via a mild hydrothermal method and further applied for photocatalytic degradation of tetracycline (TCH) and Rhodamine B (Rh B) under visible light irradiation.     

Prediction of intermediate band in Ti/V doped γ-In2S3

Materials with an intermediate energy band (IB) introduced in the forbidden gap are viable alternatives to tandem configurations of solar cells for increasing the photon-conversion efficiency. One of the aspiring designs proposed for the intermediate band concept is hyperdoped (Ti, V):In₂S₃. Being very important in copper indium gallium sulfide (CIGS) solar cells, indium thiospinel (In₂S₃) is known for its three different temperature as well as pressure, polymorphs. The most stable β-In₂S₃ was experimentally shown to have an isolated intermediate band (IB) and exhibits sub-band gap absorption due to the completely filled IB after V-doping. Though experimental observation holds a positive signature, recent DFT studies did not show a metallic intermediate band for the V dopant in the 3+ charge state. In order to clarify this, we have taken incentive from experimental XRD analysis that V-doped β-In₂S₃ shows peaks from disordered In vacancies (either α or γ), in addition to the ordered In vacancies expected. Hence, we have carried out state-of-the-art DFT based computations on pure and Ti, V-doped In₂S₃ in the γ-phase which has not been studied yet. We considered the Ti and V dopants in various charge states. Our theoretical study including hybrid functional, does in fact find the IB in V-doped γ-In₂S₃. However, at equilibrium the IB lies in between the Fermi level (E_F) and conduction band minimum (CBM).

We find the band structure of In_1.5V_0.5S₃ with HSE functional, where the vanadium atom introduces an intermediate band inside the forbidden gap in the γ-phase of In₂S₃.     

Synergistic effect of modified pore and heterojunction of MOF-derived α-Fe2O3/ZnO for superior photocatalytic degradation of methylene blue

Mesoporous heterojunction MOF-derived α-Fe₂O₃/ZnO composites were prepared by a simple calcination of α-Fe₂O₃/ZIF-8 as a sacrificial template. The optical properties confirm that coupling of both the modified pore and the n–n heterojunction effectively reduces the possibility of photoinduced charge carrier recombination under irradiation. The mesoporous Fe(25)ZnO with 25% loading of α-Fe₂O₃ exhibited the best performance in MB degradation, up to ∼100% after 150 minutes irradiation, higher than that of pristine ZnO and α-Fe₂O₃. Furthermore, after three cycles reusability, mesoporous Fe(25)ZnO still showed an excellent stability performance of up to 95.42% for degradation of MB. The proposed photocatalytic mechanism of mesoporous Fe(25)ZnO for the degradation of MB corresponds to the n–n heterojunction system. This study provides a valuable reference for preparing mesoporous MOF-derived metal oxides with an n–n heterojunction system to enhance MB photodegradation.

Mesoporous heterojunction MOF-derived α-Fe₂O₃/ZnO composites were prepared by a simple calcination of α-Fe₂O₃/ZIF-8 as a sacrificial template.     

Preparation of mesoporous ZnAl2O4 nanoflakes by ion exchange from a Na-dawsonite parent material in the presence of an ionic liquid

Herein, mesoporous ZnAl₂O₄ spinel nanoflakes were prepared by an ion-exchange method from a Na-dawsonite parent material in the presence of an ionic liquid, 1-butyl-2,3-dimethylimidazolium chloride ([bdmim][Cl]), followed by calcination at 700 °C for 2 h. The as-obtained products were characterized by several techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). The ZnAl₂O₄ nanoflakes with the thickness of ∼20 nm were composed of numerous nanoparticles, which resulted in a high specific surface area of 245 m² g⁻¹. The formation mechanism of the ZnAl₂O₄ nanoflakes was comprehensively investigated, and the results showed that a 2D growth process of the Zn₆Al₂(OH)₁₆(CO₃)·4H₂O crystallites with the assistance of [bdmim][Cl] was the key for the induction of ZnAl₂O₄ nanoflakes. Moreover, mesopores were formed between adjacent nanoparticles due to the release of CO₂ and H₂O molecules from Zn₆Al₂(OH)₁₆(CO₃)·4H₂O during the calcination process.

Herein, mesoporous ZnAl₂O₄ spinel nanoflakes were prepared by an ion-exchange method from a Na-dawsonite parent material in the presence of an ionic liquid, 1-butyl-2,3-dimethylimidazolium chloride ([bdmim][Cl]), followed by calcination at 700 °C for 2 h.     

Synthesis and high formaldehyde sensing properties of quasi two-dimensional mesoporous ZnSnO3 nanomaterials

Quasi two-dimensional (2D) mesoporous ZnSnO₃ nanomaterials (QTMZNS) were synthesized by a simple template-free hydrothermal method. The as-prepared products were characterized by TEM, SEM, XRD, TG/DTA, and FTIR. The results showed that the precursor was a mixture of Zn₅(OH)₆(CO₃)₂ and ZnSnO₃ in the hydrothermal process, and the high purity QTMZNS were obtained by calcination combined with subsequent washing of 20 wt% NH₄Cl solutions. A possible growth process and mechanism of the quasi 2D mesoporous structure was proposed. Gas sensing properties of QTMZNS were investigated, and the QTMZNS-based sensors exhibited excellent gas sensing properties. When exposed to 100 ppm formaldehyde vapors, the response sensitivity is 45.8, and the concentration limit can reach as low as 0.2 ppm of formaldehyde. All these results are much better than those reported so far, which will have great potential applications for practical air quality monitoring.

Quasi two-dimensional mesoporous ZnSnO₃ nanomaterials (QTMZNS) were synthesized and the QTMZNS-based sensor exhibited high sensitivity to formaldehyde vapors.     

Facile microwave-assisted synthesis of In2O3 nanocubes and their application in photocatalytic degradation of tetracycline

Novel In₂O₃ nanocube photocatalysts were successfully prepared by a facile microwave-assisted synthesis method. The obtained products are nano-sized with square corners and high crystallinity. The In₂O₃ nanocubes possessed high efficiency of electron–hole separation, resulting in high photocatalytic activities for the degradation of tetracycline under both visible light (λ > 420 nm) and full-range light irradiation (360–760 nm), the ratios of which are 39.3% and 61.0%, respectively. Moreover, the calculated positions of the CB and VB under our experimental conditions at the point of zero for In₂O₃ nanocubes are −0.60 V and +2.17 V, respectively. Note that the redox potentials of [O₂/·O₂⁻] and [·OH/OH⁻] are −0.33 V and +2.38 V, respectively, which means that the irradiated In₂O₃ nanocubes can reduce O₂ into ·O₂⁻ without oxidizing OH⁻ into ·OH. It can be concluded that ·O₂⁻ and h⁺ are the main active species of In₂O₃ in aqueous solution under visible light irradiation and full-range light irradiation.

Novel In₂O₃ nanocube photocatalysts were successfully prepared by a facile microwave-assisted synthesis method.     

One-step hydrothermal synthesis of a ternary heterojunction g-C3N4/Bi2S3/In2S3 photocatalyst and its enhanced photocatalytic performance

In recent years, photoelectrocatalysis has been one of the hotspots of research. Graphite-like carbon nitride (g-C₃N₄) is one of the few non-metal semiconductors known and has good potential in the field of photocatalysis due to its simple preparation method and visible light effects. In this study, a method for compounding two semiconductor materials, In₂S₃ and Bi₂S₃, on the surface of g-C₃N₄via a one-step hydrothermal method is reported, and it was found that this resulting material showed remarkable properties. The advantages of this method are as follows: (1) the formation of a heterojunction, which accelerates the separation efficiency of photogenerated carriers; (2) a large number of holes and defects on the surface of g-C₃N₄ are conducive to the nucleation, crystallisation and growth of In₂S₃ and Bi₂S₃. Compared with its counterpart catalysts, the CN/In₂S₃/Bi₂S₃ composite catalyst has significantly improved performance. Due to its high degree of crystallinity, the adsorption capacity of the catalyst itself is also significantly improved. In addition, the stability of the composite material maintains 90.9% after four cycles of use, and the structure is not damaged. In summary, CN/Bi₂S₃/In₂S₃ composite materials are believed to have broad application potential in the treatment of dye wastewater.

The proposed photocatalytic mechanism for the degradation of RhB on the surface of the 0.05CN/Bi₂S₃/In₂S₃ composite.     

A comparative electrochemical study of non-enzymatic glucose,ascorbic acid,and albumin detection by using a ternary mesoporous metal oxide (ZrO2, SiO2 and In2O3) modified graphene composite based biosensor

In this study, we present an electrochemical investigation of a ternary mesoporous metal oxide (ZrO₂, SiO₂ and In₂O₃) modified graphene composite for non-enzymatic glucose, ascorbic acid, and albumin detection in urine at physiological pH. Synergetic property of ZrO₂–Ag–G–SiO₂ and In₂O₃–G–SiO₂ were investigated via cyclic voltammetry (CV) using FTO glass and copper-foil electrodes with no prerequisite of solid antacid expansion. The mesoporous ZrO₂–Ag–G–SiO₂ and In₂O₃–G–SiO₂ composites were synthesized and characterized using XRD, SEM, TEM, Raman spectroscopy, XPS, DRS, BET, and photocurrent measurements. Upon increasing the glucose concentration from 0 to 3 mM, CV results indicated two anodic peaks at +0.18 V and +0.42 V versus Ag/AgCl, corresponding to Zr³⁺ and Zr⁴⁺, respectively, considering the presence of glucose in urine. Moreover, the effects of high surface area In₂O₃–G–SiO₂ were observed upon the examination of ZrO₂–Ag–G–SiO₂. In₂O₃–G–SiO₂ demonstrated a decent electrochemical pattern in glucose, ascorbic acid, and albumin sensing. Nevertheless, insignificant synergistic effects were observed in In₂O₃-G, ZrO₂-G, and ZrO₂–G–SiO₂. In₂O₃–G–SiO₂ performed well under a wide range of electrolytes and urine, and showed no activity toward uric acid, suggesting potential for biodetection in urine.

In this study, we present an electrochemical investigation of a ternary mesoporous metal oxide (ZrO₂, SiO₂ and In₂O₃) modified graphene composite for non-enzymatic glucose, ascorbic acid, and albumin detection in urine at physiological pH.     

PdPbAg alloy NPs immobilized on reduced graphene oxide/In2O3 composites as highly active electrocatalysts for direct ethylene glycol fuel cells

rGO-modified indium oxide (In₂O₃) anchored PdPbAg nanoalloy composites (PdPbAg@rGO/In₂O₃) were prepared by a facile hydrothermal, annealing and reduction method. Electrochemical tests showed that the as-prepared trimetallic catalyst exhibited excellent electrocatalytic activity and high resistance to CO poisoning compared with commercial Pd/C, mono-Pd and different bimetallic catalysts. Specifically, PdPbAg@rGO/In₂O₃ has the highest forward peak current density of 213.89 mA cm⁻², which is 7.89 times that of Pd/C (27.07 mA cm⁻²). After 3600 s chronoamperometry (CA) test, the retained current density of PdPbAg@rGO/In₂O₃ reaches 78.15% of the initial value. Its excellent electrocatalytic oxidation performance is attributed to the support with large specific surface area and the strong synergistic effect of PdPbAg nanoalloys, which provide a large number of interfaces and achievable reactive sites. In addition, the introduction of rGO into the In₂O₃ matrix contributes to its excellent electron transfer and large specific surface area, which is beneficial to improving the catalytic ability of the catalyst. The study of this novel composite material provides a conceptual and applicable route for the development of advanced high electrochemical performance Pd-based electrocatalysts for direct ethylene glycol fuel cells.

rGO-modified indium oxide (In₂O₃) anchored PdPbAg nanoalloy composites (PdPbAg@rGO/In₂O₃) were prepared by a facile hydrothermal, annealing and reduction method.     

Enhanced photocatalytic activity of a flower-like In2O3/ZnGa2O4:Cr heterojunction composite with long persisting luminescence

The development of new photocatalysts with high photocatalytic efficiency and catalytic stability, and long persisting luminescence is critical for ensuring environmental protection and clean energy production. In this study, we develop a flower-like In₂O₃/ZnGa₂O₄:Cr heterojunction composite with enhanced ultraviolet (UV) photocatalytic activity using a facile two-step hydrothermal method. The spectral response range of the heterojunction composite is widened to the visible-light range owing to the presence of the ZnGa₂O₄:Cr persistent luminescence nanoparticles with sizes of less than 10 nm. The heterojunction composite is dispersed on the flower petals of In₂O₃. The In₂O₃/ZnGa₂O₄:Cr/1:1 composite exhibits photo-degradation performance for rhodamine B degradation that is superior to those of pure In₂O₃, ZnGa₂O₄:Cr, In₂O₃/ZnGa₂O₄:Cr/1:0.5 and In₂O₃/ZnGa₂O₄:Cr/1:2, achieving complete degradation after 80 min under UV light irradiation. Moreover, it exhibits long afterglow luminescence that lasts for more than 72 h. Thus, the In₂O₃/ZnGa₂O₄:Cr/1:1 composite shows great potential for use in round-the-clock photocatalytic applications.

Flower-like In₂O₃/ZnGa₂O₄:Cr heterojunction composites not only have high photocatalytic efficiency for rhodamine B degradation, but also have a long persisting luminescence performance.     

A straightforward chemical approach for excellent In2S3 electron transport layer for high-efficiency perovskite solar cells

Perovskite solar cells (PSCs) have attracted significant attention in recent years owing to some of their advantages: high-efficiency, low cost and ease of fabrication. In perovskite photovoltaic devices, charge transport layers play a vital role for selectively extracting and transporting photo-generated electrons and holes to opposite electrodes. Therefore, it is very important to prepare high-quality charge transport layers using simple processes at low cost. As reported, In₂S-based electron selective layers display excellent performance including high solar-cell efficiency and negligible hysteresis. In this study, a simple chemical method was developed to prepare In₂S₃ thin films as the electron selective layers in organic–inorganic hybrid perovskite photovoltaic devices to shorten the fabrication time and simplify the technology, which can provide a new avenue for a low-cost and solution-processed method. By optimizing the preparation conditions, it was demonstrated that In₂S₃ thin film prepared using our straightforward chemical approach have higher electron extraction efficiency and comparable efficiency compared with archetypical TiO₂ as the electron transport layer (ETL) in perovskite photovoltaic device.

A simple, time-saving solution-processed In₂S₃ thin film was applied in perovskite solar cells as the electron selective layer.     

Luminescence properties in relation to controllable morphologies of Ba3[Ge2B7O16(OH)2](OH)(H2O):Eu3+ and its thermal conversion product Ba3Ge2B6O16:Eu3+

Three types of morphologies of Eu³⁺-doped Ba₃[Ge₂B₇O₁₆(OH)₂](OH)(H₂O) phosphors were obtained via hydrothermal reactions by different kinds of raw materials. In addition, Ba₃Ge₂B₆O₁₆:Eu³⁺ phosphors were obtained by calcining the precursor Ba₃[Ge₂B₇O₁₆(OH)₂](OH)(H₂O):Eu³⁺. The structure and morphology of the obtained samples were characterized by XRD, EDS, FT-IR, TG-DTA, SEM and HRTEM. Herein, the effects of the synthesis parameters, including the reaction temperature, boron sources and the rare earth doping dosage, on the photoluminescence (PL) properties of Ba₃[Ge₂B₇O₁₆(OH)₂](OH)(H₂O) were investigated in detail. The lifetime and absolute quantum yield (QY) of different morphologies of Ba₃[Ge₂B₇O₁₆(OH)₂](OH)(H₂O):Eu³⁺ were also measured. The PL properties of the Ba₃Ge₂B₆O₁₆:Eu³⁺ phosphor prepared by the precursor calcination method compared with those prepared by the high-temperature solid-state method are discussed.

The photoluminescence properties (PL) related to three morphologies of Ba₃[Ge₂B₇O₁₆(OH)₂](OH)(H₂O):Eu³⁺ have been discussed in this paper.     

A sol–gel synthesis to prepare size and shape-controlled mesoporous nanostructures of binary (II–VI) metal oxides

A base-catalyzed sol–gel approach combined with a solvent-driven self-assembly process at low temperature is augmented to make manganese oxide (Mn₃O₄), copper oxide (CuO), and magnesium hydroxide (Mg(OH)₂) nanostructures with size- and shape-controlled morphologies. Nanostructures of Mn₃O₄ with either hexagonal, irregular particle, or ribbon shape morphologies with an average diameter ranged from 100 to 200 nm have been prepared in four different solvent types. In all morphologies of Mn₃O₄, the experimental XRD patterns have indexed the nanocrystal unit cell structure to triclinic. The hexagonal nanoparticles of Mn₃O₄ exhibit high mesoporocity with a BET surface area of 91.68 m² g⁻¹ and BJH desorption average pore diameter of ∼28 nm. In the preparation of CuO nanostructures, highly nanoporous thin sheets have been produced in water and water/toluene solvent systems. The simulated XRD pattern matches the experimental XRD patterns of CuO nanostructures and indexes the nanocrystal unit cell structure to monoclinic. With the smallest desorption total pore volume of 0.09 cm³ g⁻¹, CuO nanosheets have yielded the lowest BET surface area of 18.31 m² g⁻¹ and a BHJ desorption average pore diameter of ∼16 nm. The sol of magnesium hydroxide nanocrystals produces highly nanoporous hexagonal nanoplates in water and water/toluene solvent systems. The wide angle powder XRD patterns show well-defined Bragg''s peaks, indexing to a hexagonal unit cell structure. The hexagonal plates show a significantly high BET surface area (72.31 m² g⁻¹), which is slightly lower than the surface area of Mn₃O₄ hexagonal nanoparticles. The non-template driven sol–gel synthesis process demonstrated herein provides a facile method to prepare highly mesoporous and nanoporous nanostructures of binary (II–IV) metal oxides and their hydroxide derivatives, enabling potential nanostructure platforms with high activities and selectivities for catalysis applications.

A base-catalyzed sol–gel approach combined with a solvent-driven self-assembly process at low temperature is augmented to make highly mesoporous metal oxide nanostructures of manganese and copper, and hydroxide nanostructures of magnesium.     

Multifunctional amphiphilic ionic liquid pathway to create water-based magnetic fluids and magnetically-driven mesoporous silica

Amphiphilic ionic liquids, 1-alkyl-3-methylimidazolium chloride (C_nmimCl with n = 10, 12, 14, 16) were firstly used as modifiers to construct a self-assembly bilayer on the surface of iron oxide nanoparticles for generation of highly stable, water-based magnetic fluids. Subsequently, a magnet-driven mesoporous silica was synthesized by in situ self-assembly in the bilayer C_nmimCl-stabilized magnetic fluid using the C₁₆mimCl as template and tetraethylorthosilicate (TEOS) as silicon source via a hydrothermal synthesis and following calcination procedure. A systematic study was carried out addressing the influence of the alkyl chain length of C_nmimCl in the primary and secondary layers on the stability of magnetic fluids. The characterization of TEM, XRD, VSM, electrophoresis experiments, TGA and DTA showed that stable water-based magnetic fluids can be synthesized based on the assembly of the well-defined bilayer-C_nmimCl structure with long-chain C₁₆mimCl as secondary layer on the magnetite (Fe₃O₄) nanoparticles. The results of small and wide-angle XRD, TEM, VSM, and N₂ absorption experiments indicated that the nano-scale magnetic Fe₃O₄ particles were inlayed into hexagonal p6mm mesoporous silica (MCM-41 type) framework. Importantly, it was found that the obtained Fe₃O₄/MCM-41 was an appropriate adsorbent for the adsorption of rhodamine B and methylene blue from their aqueous solution. In addition, the adsorbent could be separated and reclaimed fleetly from the solution under external magnetic field.

1-Alkyl-3-methylimidazolium chloride (C_nmimCl) can be used to construct bilayer C_nmimCl stabilized magnetic fluids, and subsequently magnetic mesoporous silica can be prepared by using the C₁₆mimCl as template in the magnetic fluids.     

The implementation of artificial neural networks for the multivariable optimization of mesoporous NiO nanocrystalline: biodiesel application

In the present research, artificial neural network (ANN) modelling was utilized to determine the relative importance of effective variables to achieve optimum specific surface areas of a synthesized catalyst. Initially, carbonaceous nanocrystalline mesoporous NiO core–shell solid sphere composites were produced by applying incomplete carbonized glucose (ICG) as the pore directing agent and polyethylene glycol (PEG; 4000) as the surfactant via a hydrothermal-assisted method. The Brunauer–Emmett–Teller (BET) model was applied to ascertain the textural characteristics of the as-prepared mesoporous NiO catalyst. The effects of several key parameters such as metal ratio, surfactant and template concentrations, and calcination temperature on the prediction of the surface areas of the as-synthesized catalyst were evaluated. In order to verify the optimum hydrothermal fabrication conditions, ANN was trained over five different algorithms (QP, BBP, IBP, LM, and GA). Among five different algorithms, LM-4-7-1 representing 4 nodes in the input layer, 7 nodes in the hidden layer, and 1 node in the output layer was verified as the optimum model due to its optimum numerical properties. According to the modelling study, the calcination temperature demonstrated the most effective parameter, while the ICG concentration indicated the least effect. By verifying the optimum hydrothermal fabrication conditions, the thermal decomposition of ammonium sulphate (TDAS) was applied to the functionalized surface areas and mesoporous walls by –SO₃H functional groups. In addition, the catalytic performance and reusability of the produced mesoporous SO₃H–NiO catalyst were evaluated via the transesterification of waste cooking palm oil, resulting in a methyl ester content of 97.4% and excellent stability for nine consecutive transesterification reactions without additional treatments.

In the present research, artificial neural network (ANN) modelling was utilized to determine the relative importance of effective variables to achieve optimum specific surface areas of a synthesized catalyst.     

Mesoporous NiO nanosphere: a sensitive strain sensor for determination of hydrogen peroxide

Exploring the sensitive and reliable methods for the determination of hydrogen peroxide (H₂O₂) is a crucial issue for the health and environmental challenges. Herein, we demonstrate a facile, but rational and effective solvothermal approach to the synthesis of hierarchical NiO mesoporous nanospheres (NiO-MNS) as an effective non-enzymatic sensor towards the H₂O₂ detection. Owing to the intercalation and stabilization effect of polyethylene glycol for the Ni(OH)₂ intermediate, the NiO mesoporous nanosphere (NiO-MNS) product is consistent with the low-dimensional nanostructured NiO blocks with large surface area and plentiful mesopores after the calcination treatment. The obtained NiO-MNS sensor presents superior electrochemical performance with a high sensitivity (236.7 μA mM⁻¹ cm⁻²) and low limit of detection (0.62 μM), as well as the good selectivity and reliability for the further application of H₂O₂ detection. In addition, the unraveling mechanism of the mesopores formation derived from the in situ measurements also offers the valuable guidance for the future design of porous materials for electrochemical devices and other applications.

The NiO mesoporous nanosphere constructing from the low-dimensional nanostructured NiO blocks presents the excellent electrochemical activity for H₂O₂ detection.     

Indium sulfide nanotubes with sulfur vacancies as an efficient photocatalyst for nitrogen fixation

We have designed and manufactured In₂S₃ nanotubes containing sulfur vacancies as effective and stable photocatalysts for nitrogen fixation and ammonia production. In the preparation process of In₂S₃, a self-templated strategy was used to obtain the nanotubes. The sulfur vacancies were then manufactured by calcination under a nitrogen atmosphere. The existence of sulfur vacancies enhances the light absorption and promotes the separation and migration of the photoinduced charge carriers. In addition, sulfur vacancies can serve as the active sites to achieve strong N₂ adsorption and activation. Thus the obtained samples show enhanced photocatalytic performance with a high NH₃ generation rate (52.49 μmol h⁻¹ g⁻¹) and excellent stability under UV-vis light.

We have designed and manufactured In₂S₃ nanotubes containing sulfur vacancies as effective and stable photocatalysts for nitrogen fixation and ammonia production.     

Hierarchically ordered macro–mesoporous anatase TiO2 prepared by pearl oyster shell and triblock copolymer dual templates for high photocatalytic activity

Hierarchically ordered macro–mesoporous anatase TiO₂ is prepared by combining the supramolecular-templating self-assembly of amphiphilic triblock copolymer P123 with a natural pearl oyster shell in a hard-templating process by a facile sol–gel reaction. The obtained materials are characterized by Raman spectroscopy, X-ray diffraction, N₂ adsorption–desorption analysis, scanning electron microscopy, and transmission electron microscopy. The results demonstrate that all TiO₂ materials obtained after calcination at various temperatures are in the anatase phase, and interestingly the resultant ordered structure of both macropores and mesopores are well-preserved after calcination at 350 °C or 450 °C, with the walls of macropores composed of ordered mesopores. However, upon calcination at 550 °C or 650 °C, while the ordered macroporous structures remain well-preserved, the mesoporous structures collapse. The photocatalytic activities of the resulting TiO₂ materials are also evaluated by photodegradation of rhodamine B under UV light irradiation. The prepared TiO₂ calcined at 450 °C shows the highest photocatalytic activity.

Hierarchically ordered macro–mesoporous anatase TiO₂ with photocatalytic activity was prepared using triblock copolymer P123 and natural pearl oyster shell as dual templates.     

Bismuth–iron-based precursor: preparation,phase composition,and two methods of thermal treatment

Bismuth ferrite (BiFeO₃) is a promising Bi-based perovskite-type material, which is multiferroic due to the coexistence of anti-ferromagnetism and ferroelectricity. During the preparation of pure BiFeO₃ nanoparticles, however, the phase structures and species of bismuth–iron-based precursor (BFOH) were still unclear, and so related precursors were prepared. X-ray diffraction, Raman, Fourier transform infrared, and X-ray absorption near-edge structure techniques were used to probe the phase structure and species of the precursors. It was found that the precursor BFOH is composed of Bi₆O₆(NO₃)₄(OH)₂·2H₂O, Bi₆O₅(NO₃)₅(OH)₃·3H₂O, Fe(OH)₃, and α-Bi₂O₃. Calcination treatment and hydrothermal synthesis were used to prepare the pure BiFeO₃ phase from the precursor BFOH. The calcination temperature was optimized as 400 °C for preparation of the pure BiFeO₃ phase. Meanwhile, hydrothermal conditions for the synthesis of the pure BiFeO₃ phase were also optimized as follows: the reaction solution was the mixture solution of Bi(NO₃)₃·5H₂O and Fe(NO₃)₃·9H₂O with cetyltrimethyl ammonium bromide (CTAB) as the surfactant and KOH as the mineralizer; the hydrothermal synthesis was performed at 180 °C for 48 h; the concentration of KOH should be at least 3 M; and the surfactant CTAB can be used to regulate the morphology of the as-prepared BiFeO₃ nanoparticles. From the point of view of the microstructure, BiFeO₃ nanoparticles prepared by calcination or hydrothermal methods have no notable differences. A formation mechanism from the precursor BFOH to the BiFeO₃ product is proposed. By providing an understanding of the precursors, this work is very helpful in the synthesis of bismuth–iron-based nanoparticles.

Preparation and phase composition study of bismuth–iron-based precursor, and its thermal treatment by calcination and hydrothermal processes, which can be used to control the synthesis of pure BiFeO₃.     

A facile synthesis of highly efficient In2S3 photocatalysts for the removal of cationic dyes with size-dependent photocatalysis

In this study, a 3D thornball-like hierarchical β-In₂S₃, displaying extremely rapid photodegradation of cationic dyes, was synthesized by a facile method. The formation of a uniform thornball-like structure depended on the microwave reaction method and citric acid as the pH regulator. The size of In₂S₃ was easily adjusted by changing the microwave irradiation time from 5 min to 15 min. The morphology, structure, composition, energy level, charge separation, and surface properties of different-sized In₂S₃ were characterized. The results showed that In₂S₃ synthesized in 10 min (In₂S₃-10) displayed optimal interface property for the electron–hole separation, maximum hydrophilia with most surface negative charges for the surface adsorption, contributing to the complete photodegradation of rhodamine B (RhB) in just 25 minutes of visible light illumination. The photodegradation path of RhB was speculated with four possible paths, including the processes of de-ethylation, open-ring of xanthene, and rupture of carbon–carbon bonds up to the decomposition into small molecules. Finally, the reusability of In₂S₃-10 was tested, obtaining nearly 96% photodegradation efficiency after sequential 5 cycles.

Different-sized thornball-like In₂S₃ were synthesized by environmentally-friendly method, which displayed excellent photodegradation of cationic dyes originating from their strong attraction.