Heterostructure Photocatalyst Research Articles

Enhanced photocatalytic performance of heterostructure CNNS@Bi2WO6 photocatalysts towards degradation of organic pollution

The flower-structured CNNS@Bi2WO6 heterostructure photocatalsts with enhanced photocatalytic performance were successfully fabricated by facile in-situ hydrothermal method. Compared with the g-C3N4 nanosheets (CNNS) and pure Bi2WO6, the flower-structured CNNS@Bi2WO6 heterostructure photocatalysts exhibited better photocatalytic performance and photocatalytic stability for degradation of rhodamine B (RhB) and tetracycline (TC) under visible. The effects of different CNNS contents on the photocatalytic efficiency of the heterostructure photocatalysts have been investigated. The results show that the CNNS@Bi2WO6 heterostructure photocatalst with CNNS mass ratio of 7% presents the best photocatalytic performance. The photocatalytic activity enhancement should be attributed to the effective separation of photogenerated electron-hole pairs and the efficient visible-light utilization efficiency. Compared with CNNS, the absorption of CNNS@Bi2WO6 photocatalysts in the visible region has been greatly strengthened, with red-shift absorption edge by the UV–vis diffuse reflectance spectra (DRS). The connection between CNNS and Bi2WO6 was studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The scavenging experiments with different trapping agents demonstrates that the photogenerated h+ in the system can play the main role during the RhB degradation process. Subsequently, the possible mechanism of photocatalytic degradation over flower-structured CNNS@Bi2WO6 heterostructure photocatalysts has been proposed.

Biochar-derived flower-like Co-Mo2C spheres/g-C3N4 photocatalyst: Engineering morphology configuration and electronic structure tuning

As a class of highly recalcitrant water contaminants, pharmaceuticals and personal care products (PPCPs) have raised considerable concerns. Here, we develop a biochar-derived flower-like Co-Mo2C sphere/g-C3N4 (CMCN) heterostructure photocatalyst for typical PPCPs degradation. The flower-like Co-Mo2C nanostructure is derived from biochar, an inexpensive and ubiquitous plant byproduct. The open-up nanoflake structure with sharp edges can induce the fast charge collection and separation. DFT calculations and experimental characterizations are conducted to fundamentally understand the enhanced intrinsic photocatalytic activity of the as-prepared CMCN photocatalysts, especially the role of Co atoms. The delocalized charge density of CMCN could be rational tailored via the increasing density of state and the difference in work functions between g-C3N4 and Co-Mo2C. The electron density of Mo 3d in CMCN is increased through integrating it with Co atoms, which possess numerous delocalized electrons. Compared with the Mo2C/g-C3N4 (MCN) bulk, the CMCN catalyst displays superior photocatalytic activity for the typical PPCPs degradation, mainly arising from the multifaceted open-up surfaces of Co-Mo2C nanoflower, the higher density of electron and more efficient charge transfer ability, as well as the prolonged life time of photogenerated charge carriers. This work provides a cheap and mild route for synthesizing Co-doped Mo2C nanoflower catalyst and expands the scope of constructing high active g-C3N4 based heterostructure.

Photocatalytic hydrogen energy recovery from sulfide-containing wastewater using thiol-UiO-66 modified Mn0.5Cd0.5S nanocomposites

The worldwide environmental pollution and energy crisis have become two main challenges currently. To this end, we aim to build a win–win strategy of clean hydrogen energy recovery with simultaneous environmental detoxification by treating sulfide-containing wastewater in a non-hazardous manner. In this study, we designed a heterostructure photocatalyst with in situ growth of MnCdS nanoparticles on thiol-functionalized UiO-66-based materials (UiOS-MCS). A series of characterization analyses showed that UiOS-MCS nanocomposites held favorable properties of efficient charge separation and migration, which thanked to well-matched band structure and tight interfacial contacts via thiol-linked bonds that greatly facilitated the transfer of photogenerated charge carriers. The optimal nanocomposite of 0.5UiOS-MCS exhibited excellent photocatalytic activity under visible light irradiation, with an impressive hydrogen evolution of 3179.36 μmol g−1 h−1 and a significant removal of sulfide contaminants in the wastewater of about 90%, selectively generating valuable oxidation product of monomeric sulfur. The mechanism analysis demonstrated that the main photoactive species required for hydrogen production by photoreduction (electrons) and sulfide removal by photooxidation (holes) were independent of each other, and that the electron-hole division of collaboration ensured an efficient and synergistic redox reaction. This work offers a promising strategy for the recovery of energy stored in wastewater and environmental remediation.

G-C3N4/W2N3 heterostructure photocatalyst for enhancing the photocatalytic degradation of methyl orange under visible light

g-C3N4/W2N3 heterostructure photocatalyst for enhancing the photocatalytic degradation of methyl orange under visible light

Development of surface modified titanium alloy as a promising photocatalyst for textile waste water treatment

TiO2 photocatalyst properties can be enhanced by doping with metals and non-metallic elements or coupling with another semiconductor forming a heterostructure photocatalyst, etc. Doped TiO2 can also be achieved by surface modification of commercially available titanium alloys by plasma electrolytic oxidation (PEO). Herein, Ti-6Al-2Sn-4Zr-6Mo, Ti-10V-2Fe-3Al and Ti-6Al-4V are PEO treated, and the photocatalytic ability of the material was studied. Further, the effect of alpha and beta stabilisers on the polymorphs of TiO2 (anatase and rutile) is investigated. Surface morphology, wettability and optical properties are analysed to determine the material’s photocatalytic ability. All titanium alloys possess a typical PEO porous structure, favouring the adsorption of dyes from the textile wastewater. The EDS and XPS analysis found that the alloying elements such as Fe, V and Mo in the titanium have limited participation in the oxidation reaction. In contrast, Al, Zr, and Sn actively participated in the PEO reaction and doped into the TiO2 lattice. The bandgap of the oxide coatings on Ti-6Al-2Sn-4Zr-6Mo, Ti-10V-2Fe-3Al and Ti-6Al-4 V alloys was found to be 2.92, 2.42 and 2.78 eV, respectively. The charge carrier’s recombination rate and separation efficiency of the PEO-treated Ti-6Al-4V and Ti-10V-2Fe-3Al are better than the PEO-treated pure Ti and Ti-6Al-2Sn-4Zr-6Mo. The PEO-treated Ti-6Al-4V alloy showed the highest MB degradation of 98% under visible light irradiation. The article successfully demonstrated PEO surface-modified commercial titanium alloys as a promising new immobilised photocatalyst for efficient textile wastewater degradation under visible light.

New updates on vanadate compounds synthesis and visible-light-driven photocatalytic applications

Photocatalysis is known as a new and cost-effective method to solve the problems of energy shortage and environmental pollution. Although the application of this method seems practical, finding an efficient and stable photocatalyst with a suitable bandgap and visible-light sensitivity remains challenging. In this context, vanadate compounds photocatalysts have been synthesized and used as emerging composites, and their efficiency has been improved through elemental doping and morphology modifications. In this review, the major synthesis methods, and the design of the latest photocatalytic compounds based on vanadate are presented. In addition, the effect of vanadate microstructures on various photocatalytic applications such as hydrogen production, CO2 reduction, and removal of organic pollutants and heavy metals are discussed. For instance, the application of a 2D-1D BiVO4/CdS heterostructure photocatalyst enhances 40 times the hydrogen production from benzyl alcohol than pure BiVO4. Similarly, the InVO4/Bi2WO6 composite has a superior photocatalytic capability for the reduction of CO2 into CO compared to pure InVO4. A CO production rate of 18 μmol.g−1.h−1 can be achieved by using this heterostructure. Regarding the organic pollutants’ removal, the use of Montmorillonite/BiVO4 structure allows a complete removal of Brilliant Red 80 dye after only 2 hours of irradiation. Finally, copper heavy metal is reduced to 90 % in water, by using BiVO4/rGO/g-C3N4 optimized photocatalyst structure. Other examples on decorated vanadate compounds for enhancing photocatalytic activities are also treated.

Enhanced photocatalytic hydrogen evolution over 0D/3D NiTiO3 nanoparticles/CdIn2S4 microspheres heterostructure photocatalyst

Constructing S-scheme heterojunction is regarded as an effective mode to motivate excellent photocatalytic performance for hydrogen generation. This paper prepares NiTiO3/CdIn2S4 S-scheme heterostructure photocatalyst by hydrothermal method successfully. In the experiments, 20 wt% NiTiO3/CdIn2S4 has the supreme photocatalytic activity with the H2 generation rate of 5168.6 μmol g−1 h−1 and the apparent quantum yield (AQY) of 5.14% at 420 nm, approximately 7.7 times of pure CdIn2S4. Through the phase characterization analyses, NiTiO3 and CdIn2S4 successfully compounded, with NiTiO3 nanoparticles wrapping around CdIn2S4 microspheres to form the irregular clumps. Further analyses of performance reveal the larger specific surface area, wider absorption region, faster charge transfer rate, outstanding photostability and recyclability for 20 wt% NiTiO3/CdIn2S4, all of which play the significant role in photocatalytic hydrogen evolution activity. Finally, a plausible S-scheme photocatalytic mechanism for NiTiO3/CdIn2S4 is proposed. This study provides a novel and effective S-scheme photocatalyst for hydrogen generation from water splitting.

Exploration of Photocatalytic Overall Water Splitting Mechanisms in the Z-Scheme SnS2/β-As Heterostructure

The Z-scheme heterostructure photocatalysts have irreplaceable advantages over other heterostructures due to their ability to separate the spatial carriers and retain strong redox ability. In this study, we explored the SnS2/β-As (β-arsenene) van der Waals heterostructure with Z-scheme properties and suitable band edge positions as a potential photocatalyst for overall water splitting. Under appropriate conditions, the hydrogen evolution reaction (HER) barrier is much closer to 0. Based on the oxidation product criteria, the SnS2/β-As heterostructure photocatalyst may generate multiple end products, including •OH, H2O2, and O2. Moreover, we screen the optimal and most possible reaction pathway OER-III under irradiation among three underlying oxygen evolution reaction (OER) mechanisms, in which the intermediate species HOOH* acts as a bridge for subsequent reactions. The solar-to-hydrogen conversion efficiency of the heterostructure can reach 17.18%. This work provides new insights into designing superior photocatalysts for overall water splitting and recognizing the OER mechanism.

Construction of 3D flower-like Bi5O7I/Bi/Bi2WO6 heterostructure decorated NiFe2O4 nanoparticles for photocatalytic destruction of Levofloxacin in aqueous solution: Synergistic effect between S-scheme and SPR action

Promoting the separation activity of photo-induced carriers via the design of heterostructure photocatalysts remains a vital challenge. In the present study, multistep strategies were developed to construct the Bi5O7I/Bi/Bi2WO6/NiFe2O4 heterojunction by in situ growth of Bi/Bi2WO6 and NiFe2O4 species on the surface of Bi5O7I microspheres, forming a 3D flower-like structure as verified by characterization technologies. The developed heterojunction reflected superior photodegradation activity (97.5% in 90 min) toward levofloxacin (LEV) under visible light irradiation. The enhanced photodegradation activity of the Bi5O7I/Bi/Bi2WO6/NiFe2O4 nanocomposite could be attributed to the synergistic outcomes of the S-scheme mechanism and the plasmonic action of Bi metal in one system. Furthermore, the Bi metal can directly harvest the simulated sunlight under the surface plasmon resonance (SPR) action, which contributes to generating a large number of electron-hole pairs. Some influencing factors like pH, LEV concentration, and catalyst loading were also discussed. The photocatalytic degradation pathways of LEV were investigated depending on the detected intermediate products. The radical experiment and ESR results stated that the major contribution of •OH, •O2−, and h+ radicals in LEV destruction. The recyclability experiments indicated the excellent stability and facile reusability of the magnetic Bi5O7I/Bi/Bi2WO6/NiFe2O4 composite. Finally, the photocatalytic mechanism for LEV destruction was clarified in terms of trapping experiments and band-gap discussions. This work introduces a clear technology to fabricate a quaternary S-scheme heterojunction boosted by the plasmonic effect of Bi metal to accelerate the charge separation ability and create a powerful redox potential to achieve a desirable LEV treatment process.

Construction of A Novel 2D/1D/‐2D RP/BP‐Bi2WO6 Composite with In Situ Junction and Z‐scheme System for Enhanced Photocatalytic H2 and H2O2 Production

AbstractExploring multifunctional photocatalysts with rational design and construction of unique transport channels is of great significance for the value‐added chemicals production and environmental remediation. In this work, a novel 2D/1D/‐2D RP/BP‐MBWO dual heterostructure photocatalyst has been successfully synthesized by loading the in‐situ grown 2D/1D RP/BP heterostructure on the 2D Bi2WO6 nanosheets. through simple ultrasonic agitation.Benefiting from this favourable interfacial and structural characteristics, the fabricated BP/RP‐MBWO photocatalyst shows a sharply improved photocatalytic H2 and H2O2 evolution performance. Excitingly, the optimal of H2O2 production rate of the BP/RP‐Bi2WO6 composites is as high as 622.5 μmol g−1 h−1 under visible light irradiation, which is approximately 15 times as that of pure MBWO. The hydrogen production performance of the complexes was significantly improved compared to the pure MBWO samples. When the BP/RP loading was 20 %, the prepared nanocomposites showed the highest photocatalytic hydrogen evolution efficiency with the hydrogen production rate of about 0.77 μmol ⋅ g−1 ⋅ h−1. This work is expected to offer a new inspiration for the rational design and construction of effcient photocatalyst systems toward solar energy capture and conversion.

Ti3C2@g-C3N4/TiO2 Ternary Heterogeneous Photocatalyst for Promoted Photocatalytic Degradation Activities

Ternary heterojunction photocatalysts can improve the transport and separation of photogenerated electrons and holes, which could promote their reduction and oxidation properties for environmental and energy applications. In this research, the ternary photocatalyst Ti3C2@TiO2/g-C3N4 was successfully synthesized via direct electrostatic self-assembly during hydrothermal process. Ti3C2 MXene was used to optimize the interfacial carrier transport and separation between the interfaces. The obtained ternary heterostructured photocatalyst had a higher photocatalytic degradation performance for removing rhodamine B (RhB) and 4-chlorophenol (4-CP). The synergistic effect of heterojunction between g-C3N4 and TiO2 and Schottky barrier presented among TiO2 and Ti3C2 suppressed the recombination of the photogenerated electron–hole pairs. Moreover, the Ti3C2 can serve as an active site for the adsorption and activation of organic pollutants resulting from sufficient functional groups (F− here).

Two Birds with One Stone: Copper-Based Adsorbents Used for Photocatalytic Oxidation of Hg0 (Gas) after Removal of PH3.

CuX/TiO2 adsorbents with CuO as the active component were prepared via a simple impregnation method for efficient purification of phosphine (PH3) under the conditions of low temperatures (90 °C) and low oxygen concentration (1%). The PH3 breakthrough capacity of optimal adsorbent (Cu30/TiO2) is 136.2 mg(PH3)·gsorbent-1, and the excellent dephosphorization performance is mainly attributed to its abundant sur face-active oxygen and alkaline sites, large specific surface area, and strong interaction between CuO and the support TiO2. Surprisingly, CuO is converted to Cu3P after the dephosphorization by CuX/TiO2. Since Cu3P is a P-type semiconductor with high added value, the deactivated adsorbent (Cu3P/TiO2) is an efficient heterostructure photocatalyst for photocatalytic removal of Hg0 (gas) with the Hg0 removal performance of 92.64% under visible light. This study provides a feasible strategy for the efficient removal and resource conversion of PH3 under low-temperature conditions and the alleviation of the environmental risk of secondary pollution.

Graphitic carbon nitride functionalized with Cu-doped Bi2S3 as a heterostructure photocatalyst for the visible light degradation of methyl orange

The combination of carbon-based materials with semiconductor nanoparticles of different structures promotes the unique properties that arise from the construction of heterojunctions. This improves the charge separation, and enhances the light absorption and steadiness of the composite. Thus, it offers a promising approach to achieving an efficient photocatalyst. In this study, the photocatalytic activity of graphitic carbon nitride and copper-doped bismuth sulphide heterostructure (g-C3N4/Cu–Bi2S3) obtained by the solvothermal method is reported. The prepared heterostructures were characterized to understand their morphological, optical, and electronic properties, and the photocatalytic activity for the degradation of methyl orange was studied. The formation of heterostructure between g-C3N4 and Cu–Bi2S3 led to a narrowing of band gaps compared to the pristine g-C3N4 and Cu–Bi2S3. Evaluation of the photocatalytic activity of the heterostructure showed about 95% degradation efficiency for methyl orange. The radical scavenging studies showed that superoxide radicals and photogenerated holes had the most significant impact on the photocatalytic process. The results confirm that the formation of the heterostructure of g-C3N4 with semiconductor nanomaterials offers a unique and facile route to enhancing the catalytic degradation of dyes.

Ferroelectric polarization and interface engineering coupling of Z-scheme ZnIn2S4/α-In2Se3 heterostructure for efficient photocatalytic water splitting

It is of great significance to design an efficient heterostructure for photocatalytic hydrogen production to solve the energy shortage and environmental crisis. In this letter, we investigate the structure, electron of interface, optical, charge transfer, and photocatalytic mechanism of three different ZnIn2S4/α-In2Se3 heterostructures by hybrid density functional calculation. It is interesting that the presence of an external electric field not only can change the bandgap but also can modulate the band alignment type. Among them, heterostructure A belongs to type II heterostructure, and heterostructure B and C belong to a Z-scheme heterostructure. Especially in heterostructure C, the electrons deposited on CBM of a ZnIn2S4 monolayer will play an important role in the hydrogen production process. Meanwhile, the small bandgap of ZnIn2S4/α-In2Se3 Z-scheme heterostructures enables it to obtain a wide light absorption range. Therefore, this study contributes to the design of a novel and potential Z-scheme heterostructure photocatalyst with broad application prospects in both electronic and optoelectronic fields.

A hierarchical Bi-MOF-derived BiOBr/Mn0.2Cd0.8S S-scheme for visible-light-driven photocatalytic CO2 reduction

S-scheme heterojunctions have promising applications in photocatalytic CO2 reduction due to their unique structure and interfacial interactions, but improving their carrier separation efficiency and CO2 adsorption capacity remains a challenge. In this work, highly dispersed MOF-BiOBr/Mn0.2Cd0.8S (MOF-BiOBr/MCS) S-scheme heterojunctions with high photocatalytic CO2 reduction performance were constructed. The intimate contact between the MCS nano-spheres and the nanosheet-assembled MOF-BiOBr rods, driven by the internal electric field, accelerates the charge transfer along the S-scheme pathway. Moreover, the high specific surface area of MOFs is preserved to provide abundant active sites for reaction/adsorption. The formation of MOF-BiOBr/MCS S-scheme heterojunction is confirmed by theoretical calculations. The optimum MOF-BiOBr/MCS shows excellent activity in CO2 reduction, affording a high CO evolution rate of 60.59 µmol h−1 g−1. The present work can inspire the exploration for the construction of effective heterostructure photocatalysts for photoreduction CO2.

Assembly of a novel Fe2TiO5-impregnated donor-π-acceptor conjugated carbon nitride for highly efficient solar water splitting

Carbon nitride (CN) exhibits low photocatalytic performance for the energy conversion during photocatalytic water splitting (PWS) under visible light spectrum. Designing novel high-performance CN-based photocatalysts via providing advanced intrinsic characteristics to pristine CN material may further endorse the PWS process. Integrating organic molecules within the skeleton of CN is an interesting strategy to lessen the extent of charge recombination by promoting effective charge separation and transportation, thereby boosting light absorption and photocatalytic performances. Yet, limited progresses have been made along this line. We have carefully chosen and fused previously unexplored organic donor-π-acceptor-type 2,6-diaminopurine (DP) molecules within the skeleton of CN via a superficial organic molecular engineering. Moreover, the subsequent introduction of Fe2TiO5 with copolymerized CN-DP10.0 and pristine CN provide considerably more surface-active sites to form heterojunction material, synergistically extending both the optical absorption range and the lifetime of photoinduced electron. More importantly, with a typical type-II heterojunction formation, the CN and Fe2TiO5 energy levels are overlapped and compatible, thereby significantly accelerating both electron and hole transfer processes. These beneficial characteristics in turn lead to an outstanding apparent quantum yield (AQY) of 61.7% at a wavelength of 420 nm, together with highly efficient and greatly improved photocatalytic hydrogen (H2) (165.7 μmol/h) along with oxygen (O2) (6.2 μmol/h) evolution reactions in visible spectrum at 420 nm. These values are 15.7 and 11.4 times more than those of the pristine CN (9.9 μmol/h and 0.5 μmol/h). Consistent with these experimental findings, our computational simulations show that integration of Fe2TiO5 and DP molecules within the CN framework decreases the band gap from 3.25 to 2.55 eV, suggesting remarkable photocatalytic activities of Fe2TiO5/CN-DP10.0. As a result, it is anticipated that this work will offer a significant avenue for scientific investigation into the next generation of renewable energy employing improved heterostructure photocatalyst predicated on organic ligands.

Enhanced Photocatalytic H2 Evolution Performance of the Type-II FeTPPCl/Porous g-C3N4 Heterojunction: Experimental and Density Functional Theory Studies.

It is of great significance to improve the photocatalytic performance of g-C3N4 by promoting its surface-active sites and engineering more suitable and stable redox couples. Herein, first of all, we fabricated porous g-C3N4 (PCN) via the sulfuric acid-assisted chemical exfoliation method. Then, we modified the porous g-C3N4 with iron(III) meso-tetraphenylporphine chloride (FeTPPCl) porphyrin via the wet-chemical method. The as-fabricated FeTPPCl-PCN composite revealed exceptional performance for photocatalytic water reduction by evolving 253.36 and 8301 μmol g-1 of H2 after visible and UV-visible irradiation for 4 h, respectively. The performance of the FeTPPCl-PCN composite is ∼2.45 and 4.75-fold improved compared to that of the pristine PCN photocatalyst under the same experimental conditions. The calculated quantum efficiencies of the FeTPPCl-PCN composite for H2 evolution at 365 and 420 nm wavelengths are 4.81 and 2.68%, respectively. This exceptional H2 evolution performance is because of improved surface-active sites due to porous architecture and remarkably improved charge carrier separation via the well-aligned type-II band heterostructure. Besides, we also reported the correct theoretical model of our catalyst through density functional theory (DFT) simulations. It is found that the hydrogen evolution reaction (HER) activity of FeTPPCl-PCN arises from the electron transfer from PCN via Cl atom(s) to Fe of the FeTPPCl, which forms a strong electrostatic interaction, leading to a decreased local work function on the surface of the catalyst. We suggest that the resultant composite would be a perfect model for the design and fabrication of high-efficiency heterostructure photocatalysts for energy applications.

Recent advances in designing ZnIn2S4-based heterostructured photocatalysts for hydrogen evolution

• This review mainly introduced various ZnIn 2 S 4 -based heterojunctions and their PHE application. • In-depth discussion on the mechanisms of various ZnIn 2 S 4 -based heterojunction systems for boosting PHE efficiency is provided. • We expressly introduced overall water splitting, dual-functional and photothermal effect-assisted PHE systems. • Some identification methods are presented for confirming heterojunction types. • The current states, challenges and perspectives of ZnIn 2 S 4 -based heterostructured photocatalysts for PHE are discussed. Water and solar energy are inexhaustible on Earth, and thus hydrogen evolution through photocatalytic water splitting taking sunlight as the input energy is an ideal green energy generation technology. As a typical visible-light-responsive photocatalyst, ZnIn 2 S 4 attracted worldwide research attention because of its many advantages for photocatalytic hydrogen evolution (PHE), such as layered structure, simple syntheses, structural stability, environmental friendliness, and suitable electronic band structure. In recent years, constructing ZnIn 2 S 4 -based heterostructured photocatalysts has become a research focus for their significantly improved spatial charge carrier separation efficiency and PHE performances. According to the charge carrier transfer/separation mechanisms, heterostructured ZnIn 2 S 4 -based photocatalysts are divided into five categories, conventional heterojunctions (type-I and type-II), p-n heterojunction, Z-scheme heterojunction, S-scheme (or Step-scheme) heterojunction, and co-catalyst deposition based heterojunction systems. This article reviews the recent advances in ZnIn 2 S 4 -based heterostructured photocatalysts for PHE. Firstly, the central part of this review introduced various ZnIn 2 S 4 -based heterojunctions and their PHE application. Secondly, apart from common half-reaction of water-splitting, we expressly introduced overall water splitting, dual-functional and photothermal effect-assisted PHE systems. Then, we briefly presented some identification methods for confirming heterojunction types. Finally, the current states, challenges and perspectives of ZnIn 2 S 4 -based heterostructured photocatalysts for PHE are also discussed. This review aims to explore the advantages of diverse ZnIn 2 S 4 -based heterostructures, and can provide an insight into designing high-efficiency heterostructured photocatalysts for PHE application.

Ternary V-Scheme Ag2WO4/BaO/NiO Heterojunction Photocatalysts: Very Fast Degradation Process for Congo Red under UV-Light Irradiation.

With increasing industrial production, pollutants generated in the process of bleaching or dying disperse to the natural water medium. Therefore, an effective photocatalytic material must be prepared for water treatment quickly. In the present study, a novel and effective V-scheme Ag2WO4/BaO/NiO heterostructure photocatalyst with high photocatalytic performance for the degradation of different organic pollutants was designed and formed by a simple precipitation method. Scanning electron microscopy images showed that BaO, NiO, and Ag2WO4/BaO/NiO have a nanopipe, spherical, and nanorod morphology, respectively. X-ray diffraction results indicated that cubic phases were obtained with higher crystallite structure and lower crystallite distortion. The optical properties of the samples exhibited UV-absorption regions with about 3.35, 3.38, and 3.28 eV band gaps for BaO, BaO/NiO, and Ag2WO4/BaO/NiO, respectively. The photocatalytic activity was investigated by the degradation of Congo red under UV-light irradiation. To investigate the photocatalytic mechanism, the photodegradation performance of the catalyst was analyzed with different scavengers such as isopropyl alcohol, ascorbic acid, and potassium iodide (KI), and it was shown that the main active species were •O2 - radicals and that OH• radicals have a significant contribution toward the degradation process. Compared to bare BaO and BaO/NiO samples, Ag2WO4/BaO/NiO showed excellent photocatalytic activity and about 41%, 66 and 99% of Congo red photodegraded under UV light within 30 min. The reason for this is that the Ag2WO4/BaO/NiO heterostructure displayed wider contact which promoted more charge-transfer ways to shorten the electron transportation path and increase the inhibition of electron-hole pairs.

Construction of 2D/2D Bi12O17Cl2/Zn-HMT Z-scheme heterojunction for efficient photocatalytic tetracycline hydrochloride degradation and Cr(Ⅵ) reduction

Although photocatalysis technology is one of prospective method attributing to enormous potentials to environment issues, searching high-efficiency and stable photocatalysts remains the enormous challenges. In this work, we successfully constructed a novel 2D/2D Z-scheme heterostructure photocatalyst (BMT) in composed of Zn(Ⅱ)-hexamethylenetetramine (Zn-HMT) and Bi12O17Cl2 forming a 2D sheet-sheet stacking structure. The 2D/2D Z-scheme Bi12O17Cl2/Zn-HMT with intimate face-to-face contact inherits unique merits including large contact surface, abundant exposed active sites and shortened transmission paths of electrons, which would promote the separation of charges and the transmission efficiency of electrons in photocatalytic reaction. Attributing to these superiorities, the sample of 0.75-BMT with optimal proportion shows admirable photocatalytic performance for the photocatalytic tetracycline hydrochloride (TC-HCl, k1 =1.0 h−1) degradation and hexavalent chromium (Cr (Ⅵ), k2 = 0.43 h−1) reduction, which are about 2.6 and 4.3 times of pristine Zn-HMT, respectively. This work provides inventive inspiration for constructing a novel 2D/2D Z-scheme photocatalyst as the effect way to handle the environmental pollution issues.