Z-scheme Heterostructure Photocatalysts Research Articles

Enhanced light absorption and charge carrier’s separation in g-C3N4-based double Z-scheme heterostructure photocatalyst for efficient degradation of navy-blue dye

ABSTRACT Effective wastewater treatment is essential due to the dye environmental threats. Photocatalysis offers an eco-friendly dye degradation solution. Herein, we report a double Z-scheme photocatalyst, i.e. LaFeO3/Boron-doped g-C3N4/Fe2O3 (LFO/B-CN/FO), fabricated via a hydrothermal method. The formation of this ternary system is supported by structural, surface, and morphological analyses. Differential scanning calorimetry and thermal gravimetric analysis demonstrated the crystallization behavior of the composite. Because of synergetic effects in the ternary composite and boron doping, the optical band gap energy is reduced to 1.6 eV. Under visible light irradiation, the LFO/B-CN/FO nanocomposite degraded navy-blue dye by 98% in 130 min at neutral pH, surpassing CN, B-CN, and binary composites of B-CN with LFO and FO. The degradation process was rationalized using pseudo-first- and pseudo-second-order kinetic models, which confirmed high catalytic efficiency. The double Z-scheme heterojunction enhanced light absorption, charge separation, and carrier lifetime, hence improving the photocatalytic activity. Overall, the as-fabricated LFO/B-CN/FO ternary composite outperformed reference catalysts in terms of chemical reactivity, optical characteristics, and electrical performance. This work opens up a new route for the design and fabrication of double Z-scheme ternary composite photocatalysts for potential wastewater treatment and renewable energy applications.

Preparation of MgIn2S4/g-C3N4 for enhanced ranitidine photocatalytic degradation activity via Z-scheme electron transfer

The evidence so far indicates that ranitidine (RAN) contains N-nitrosodimethylamine (NDMA), a strong carcinogen, which is extremely harmful to human health under long-term exposure. Hence, a well-design Z-scheme heterostructure composed of 3D MgIn2S4 micro-flower and 2D g-C3N4 nanosheets was fabricated and used to remove RAN. The optimal photocatalyst (MG-30) exhibited the fastest RAN degradation rate of 0.24685 min−1 within 30 min under visible light, which was 78.1 and 19.8 times higher than those of bare MgIn2S4 and g-C3N4, respectively. Impressively, MG-30 was exceedingly resistant to environmental variations including organic matter, inorganic salts and aqueous substrates. In the meantime, MG-30 boasted the merit such as wide pH range for RAN removal. The excellent results originated from the construction of Z-scheme heterojunctions, which improved the carrier separation efficiency and retained the strong redox ability of MG-30, thereby contributing to the creation of rich active species. Meanwhile, the 3D/2D structure of MgIn2S4/g-C3N4 overrode the limited reflection of visible light. The active species analyses revealed that superoxide radical (·O2−) and hydroxyl radical (·OH) mainly participated in RAN degradation. Furthermore, the possible degradation pathways of RAN and toxicity analysis of intermediates produced were presented. This work emphasizes practical application potential of Z-scheme heterostructure photocatalysts for emerging contaminants degradation in wastewater.

Construction of novel g-C3N4/β-FeOOH Z-Scheme heterostructure photocatalyst modified with carbon quantum dots for efficient degradation of RhB

The degradation of organic pollutants using semiconductor photocatalysts is a new ecological approach, but the currently available photocatalysts are not very efficient. Herein, in order to obtain efficient visible-light photocatalysts, g-C3N4/β-FeOOH-modified carbon quantum dots (CDs) composite photocatalysts with Z-Scheme charge transfer mechanism were successfully synthesized. The phase composition and morphology of the composite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrophotometry (FT-IR), and X-ray photoelectron spectroscopy (XPS) techniques. Due to the upconversion effect of the CDs, the optical response range of the composite was effectively widened, and the optical utilization rate was improved. The Z-Scheme heterostructure not only improves the light trapping ability, significantly inhibits charge-carrier complexation, and realizes the spatial separation of redox sites, but also ensures that the photocatalyst maintains a suitable valence-conductivity band position and maintains the strong redox reactivity. In addition, CDs have the unique characteristics of electronic storage and transfer, which effectively enhance the quantum separation efficiency of the composite. The photocatalytic efficiency was measured by degrading rhodamine B (RhB) under visible light. The degradation performance was the best when the weight ratio of CDs was 6%, and the RhB solution degradation rate reached 100 % in 60 min. The unique structure and reliable mechanism provide a way for the development of advanced photocatalyst.

Interfacial chemical bond regulating the electronic coupling of ZnIn2S4−x-WO3−x for enhancing the photocatalytic pollutions degradation coupled with hydrogen evolution

Constructing Z-scheme heterostructure photocatalysts with a staggered band structure holds great potential to realize synergistic oxidation and reduction reactions. However, the Z-scheme heterostructure with interfacial vacancies significantly disturbs the behaviors of charge transfer and remains a challenging as well as urgent issue to exploit. Here, the ultrathin ZnIn2S4−x-WO3−x Z-scheme heterostructure (ZW) was synthesized via a facile in situ hydrothermal strategy. Experimental results and DFT calculations unveiled that the dual vacancies induced the formation of interfacial bonds. Importantly, the interfacial bonds tremendously modulate the electronic structure of heterostructure for enlarging the built-in electric field and reducing the aggregation effect of charge in the interface vacancies, which contributed to promoting charge transfer through the interface as well as exciton dissociation. Ultimately, the optimized ZW-4 exhibited an exceptional photocatalytic hydrogen evolution performance of 737.75 μmol g−1 h−1 and a pollution degradation rate greater than 99.99% without using any cocatalyst under visible light irradiation. Our work offers a deep insight into the ideal charge migration paths in highly efficient Z-scheme heterojunctions with vacancies.

Construction of Z-Scheme MoS2/ZnFe2O4 heterojunction photocatalyst with enhanced photocatalytic activity under visible light

Construction of direct Z-scheme heterostructure photocatalysts with improved photogenerated charge carriers has gained considerable attention during the past few years. In this work, a direct Z-scheme MoS2/ZnFe2O4 heterostructure photocatalyst was synthesized via a facile hydrothermal method. The photocatalytic activity of this photocatalyst was evaluated through degradation of methylene blue (MB) dye under visible light irradiation. The MZF-25 catalyst showed high catalytic activity with a degradation efficiency of 92.3%, higher than that of pristine MoS2 and ZnFe2O4. Further, the reusability of the MoS2/ZnFe2O4 heterostructure was analysed and there was no significant loss in the photocatalytic activity even after four cycles. Finally, the Z-scheme mechanism of the MoS2/ZnFe2O4 photocatalyst was determined for the degradation of MB. This work provides a promiosing strategy for designing MoS2/ZnFe2O4-based Z-scheme heterostructures for removal of organic pollutants.

In-situ construction of novel sulfur-vacancy-rich Bi/Bi2S3/SnS2 Z-scheme heterostructure photocatalysts for efficient Cr(VI) reduction and nitrogen fixation

Highly competent and economical photocatalysts are one of the most charming targets in environmental restoration and clean production. Herein, a novel sulfur-vacancy-rich Bi/Bi2S3/SnS2 Z-scheme heterostructure was constructed in situ and applied for the photoreduction Cr(VI) and nitrogen fixation. The fabricated Bi/Bi2S3/SnS2–2 exhibits the optimum photoreduction Cr(VI) performance with the efficiency of 94.5% within 15 min visible light irradiation. The remarkably enhanced catalytic efficiency derived from the synergistic effect of the construction of intimate contacted interface, abundant sulfur vacancy and surface plasmon resonance (SPR) effect of metal Bi. Meanwhile, the excellent photocatalytic nitrogen fixation property (96.4 μmol g–1 h–1) was achieved by Bi/Bi2S3/SnS2–2 under full solar illumination because sulfur vacancy could provide sufficient catalytic sites to accelerate the adsorption and nitrogen activation. The Z-scheme heterostructure was proposed to expound the photocatalytic mechanism. This work offers a new perspective on hierarchical heterostructure with plentiful vacancies for environmental remediation and energy development.

Enhanced ultraviolet–visible–near infrared driven photocatalytic activity of 1D/0D BiVO4:Er/Yb@Ag/Ag3PO4 Z-scheme heterostructure via a synergetic strategy of plasmonic effect and upconversion luminescence

Expanding the spectral response range to near-infrared (NIR) region and improving carrier separation are the two critical strategies to obtain highly efficient photocatalysts for water pollution control. Herein, a new type of photocatalyst one-dimensional/zero-dimensional (1D/0D) BiVO4:Er/Yb@Ag/Ag3PO4 Z-scheme heterostructure with full spectral response is constructed by an electrospinning coupled with an ethylene glycol assisted hydrothermal method. The optimized BiVO4:Er/Yb@Ag/Ag3PO4 heterostructured nanofibers degrade 69.5% (9 h) and 91.3% (30 min) of tetracycline hydrochloride (TC), 76.7% (9 h) and 99.4% (24 min) of methylene blue (MB) and 38.2% (9 h) and 94.5% (60 min) of bisphenol A (BPA) under NIR light and simulated sunlight excitation, respectively. Under NIR light and simulated sunlight excitation, the MB removal efficiencies of the optimal composite are 9.833 and 1.094 times of Ag3PO4 and 20.184 and 11.558 times of BiVO4, respectively. The superior photocatalytic activity can be attributed to the synergistic effects of the unique 1D/0D contact interface, the porous outer wall of BiVO4:Er/Yb nanofibers, Ag bridged Z-scheme heterostructure, upconversion (UC) luminescence and the surface plasmon resonance (SPR) effect. This makes BiVO4:Er/Yb@Ag/Ag3PO4 heterostructured nanofibers have the advantages of broadened absorption spectrum, abundant active sites, increased specific surface area, fast electron transfer channels, improved carrier separation efficiency, enhanced photocorrosion resistance and stability. This work provides a new insight in designing and constructing high-performance Ag bridged Z-scheme heterostructure photocatalysts with full spectral response for water pollution control.

Exceptional Photocatalytic Performance of the LaFeO3/g-C3N4 Z-Scheme Heterojunction for Water Splitting and Organic Dyes Degradation

To simulate natural photosynthesis, scientists have developed an artificial Z-scheme system that splits water into hydrogen and oxygen using two different semiconductors. Researchers are striving to improve the performance of Z-scheme systems by improving light absorption, developing redox couples with high stability, and finding new cocatalysts. Here, we report the synthesis and utilization of LaFeO3/g-C3N4 as a Z-scheme system for water reduction to produce hydrogen and organic dye degradation under visible light irradiation. The as-fabricated photocatalyst revealed exceptional activity for H2 production (i.e., 351 µmol h−1g−1), which is 14.6 times higher compared to that of the single-component g-C3N4 (i.e., 24 µmol h−1g−1). In addition, the composite photocatalyst degraded 87% of Methylene Blue (MB) and 94% of Rhodamine B (RhB) in 2 h. Various experimental analyses confirmed that the exceptional performance of the LaFeO3/g-C3N4 Z-scheme catalyst is due to remarkably enhanced charge carrier separation and improved light absorption. The development of this highly effective Z-scheme heterostructure photocatalyst will pave the way for the sustainable development of newly designed Z-scheme scheme systems that will tackle energy and environmental crises.

Construction of novel fluorescent synergistic photocatalytic double Z-scheme photocatalyst for efficient antifouling of polydimethylsiloxane coatings

It has been challenging to enhance the static antifouling (AF) performance of silicone AF coatings using low-cost, high-performance, and environmentally friendly materials. In this work, a graphite-phase carbon nitride/titanium dioxide nanotubes/Sr2MgSi2O7:(Eu2+, Dy3+) long afterglow powder (g-C3N4/TNTs/SLAP, CTS) ternary double Z-scheme heterostructure photocatalyst was designed based on the application of photocatalytic technology in the field of AF and environmental remediation and the function of fluorescent corals and Watasenia scintillans emitting fluorescence to prevent the adhesion of fouling organisms. Then, this composite photocatalyst was dispersed in polydimethylsiloxane resin (PDMS) to prepare g-C3N4/TNTs/SLAP/PDMS (P-CTS) biomimetic fluorescent synergistic photocatalytic AF coating. The double Z-scheme heterostructure formed between the CTS enhances the carrier separation and transport efficiency, thus conferring excellent visible light photocatalytic activity on the CTS. At the same time, the fluorescence emitted by SLAP as a “light store” at night not only prolongs the photocatalytic activity but also inhibits the adhesion of fouling organisms. The results showed that the minimum attachment rates of S. aureus, E. coli, and benthic diatoms of P-CTS were 1.65 %, 1.40 %, and 10.20 %, respectively, under simulated natural diurnal conditions. This novel biomimetic fluorescent synergistic photocatalytic AF coating has good potential applications in marine AF and environmental remediation.

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.

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.

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.

Rational design of defect metal oxide/covalent organic frameworks Z-scheme heterojunction for photoreduction CO2 to CO

Z-scheme heterostructure consisting of covalent organic frameworks (COF) and inorganic semiconductor possesses tremendous potential for achieving efficient photoreduction of CO2. However, the precise design and rationalization of the interaction between COF and inorganic semiconductors remains a great challenge. Herein, the interaction of different N-sites on T−COF framework with defect TiO2 and stoichiometric TiO2 is investigated by density functional theory. The theoretical analysis suggests that the amine group of T−COF could provide an energetically favored binding site towards defect TiO2. Accordingly, a stable Z-scheme heterostructure with well-defined chemical bonding between Ti3+ and −NH2, and well-engineered geometry configuration through in situ anchoring defect TiO2 on the surface of amine-functionalized T−COF sphere is designed. The obtained heterostructure exhibits a high CO2-to-CO conversion efficiency, with nearly 100 % CO selectivity and an apparent quantum efficiency of 6.81 % at 365 nm. This work could provide guidance for the rational design of Z-scheme heterostructure photocatalysts for photocatalytic applications in high efficiency.

Internal electric field enhanced photoelectrochemical water splitting in direct Z-scheme GeC/HfS2 heterostructure: A first-principles study

Designing direct Z-scheme heterostructure photocatalysts has received enormous attention due to the efficient separation of photo-generated carriers in water splitting. Based on first-principles calculations, electronic properties and a photocatalytic mechanism of a GeC/HfS2 van der Waals (vdW) heterostructure are systematically explored. From the analysis of band arrangement and the built-in electric field, the heterostructure, with an indirect bandgap of 0.40 eV, is demonstrated to be a typical direct Z-scheme system. Remarkably, there is also a 0.40 eV interlayer work function difference in the heterostructure, which is helpful to further drive carrier separation and enhance the water splitting ability by partially bending the redox potential of water. The Gibbs calculation shows that the GeC/HfS2 vdW heterostructure can achieve overall photocatalytic water splitting spontaneously under neutral conditions. Moreover, excellent visible light absorption ability (∼5×105 cm−1) and giant carrier mobilities (5823 cm2 V−1 s−1) also make GeC/HfS2 heterostructure highly competitive in numerous photocatalytic materials and optoelectronic devices. The bandgap can be flexibly adjusted by biaxial strain, enabling a wider application of the heterostructure. All these significant properties not only demonstrate the great application potential of GeC/HfS2 heterostructure as photocatalysis but also provide ideas for designing novel electric field-enhanced heterostructures.

W/Mo-heteropoly blue-modified defective W18O49 as Z-Scheme heterostructure photocatalysts for efficient N2 fixation

Photocatalytic N2 fixation can convert the abundant but inert N2 into NH3 under atmospheric conditions. However, the dissatisfactory yield rate of NH3 greatly hinders its development. The rational design of a highly efficient N2 fixation photocatalyst enables large-scale ammonia production but is challenging due to the thermodynamic obstacles of N2 activation. Herein, the W/Mo-heteropoly blue modified defective W18O49 heterojunction composite catalysts (r-HPW/W18O49 and r-HPMo/W18O49) are prepared for N2 photofixaiton without sacrificial agents and cocatalysts under ambient conditions for the first time. The heteropoly blue nanoparticles are loaded on the surface of W18O49 by electro-reduction and subsequent solvothermal methods. The as-fabricated r-HPW/W18O49 show unusual activity with NH3 formation rates of 184.54 µmol g−1 h−1, about 2.6 times higher than that of initial W18O49. The excellent photocatalysis property is attributed to the synergistic effect between W18O49 and heteropoly blues. The defective W18O49 provides rich active sites for the effective adsorption of N2 molecules and acts as a robust support to inhibit the aggregation of heteropoly blues. The photo-generated electrons in W18O49 quickly transfer to the heteropoly blues, retarding charge pair recombination and enabling the constructed “Z-Scheme” heterostructure to stronger redox capacity. This work offers a new perspective for preparing advanced heteropoly blues-based N2 photofixation nanomaterials.

BiOBr/MXene/gC3N4 Z-scheme heterostructure photocatalysts mediated by oxygen vacancies and MXene quantum dots for tetracycline degradation: Process, mechanism and toxicity analysis

The rapid recombination rate of photogenerated charges make the rational design of high-performance stable photocatalysts challenging. Herein, the features of heterojunctions, oxygen vacancies (OVs), and MXene quantum dots (MQDs) were simultaneously collected in CBM (gC3N4/BiOBr/MXene) using a simple solvothermal method for the first time. OVs promoted the chemisorption of O2, MQDs not only accelerated electron transport but also promoted a photogenerated charge to selectively generate singlet oxygen, 99% of the tetracycline hydrochloride (TC-HCl) was degraded by CBM within 30 min under visible light irradiation. Thirteen intermediates and possible photocatalytic degradation pathways were proposed. It was discovered that CBM is nontoxic to the environment but can swiftly produce an excellent antibacterial effect when exposed to visible light irradiation. This research provides fresh insights into the effective removal of organic pollutants from water by combining cutting-edge defect engineering and quantum dot doping technology in photocatalytic heterojunctions.

Novel 3D Cu2O/N-CQD/ZIF-8 composite photocatalyst with Z-scheme heterojunction for the efficient photocatalytic reduction of Cr(Ⅵ)

ZIF-8 exhibits poor visible light response and rapid electron-hole recombination. To address these problems, we constructed an N-CQD/ZIF-8 framework by in-situ synthesis method, then prepared a novel Z-scheme heterostructure photocatalyst (Cu2O/N-CQD/ZIF-8) by reduction precipitation method for the efficient photocatalytic reduction of Cr(Ⅵ). Cu2O/N-CQD/ZIF-8 (with a 10% Cu2O loading) had a unique heterostructure and exhibited significantly improved performance for Cr(Ⅵ) photoreduction. This photocatalyst successfully reduced 98.99% of the Cr(Ⅵ) in a pH = 3 solution system, which was 6 times higher than that of ZIF-8. Meantime, due to its stable interfacial adhesion, the reduction efficiency of Cr(Ⅵ) by Cu2O/N-CQD/ZIF-8 still reached 97.13% after five cycles. Therefore, Cu2O/N-CQD/ZIF-8 exhibited superior photocatalytic activity and recyclability compared with unmodified ZIF-8. The charge transfer path of this Z-scheme heterojunction was verified by free radical trapping experiments and X-ray photoelectron spectroscopy. Moreover, a possible charge transfer mechanism was proposed. N-CQD provided a potential driving force for the construction of the internal Z-scheme charge transfer system. Moreover, the synergistic effect between Cu2O and ZIF-8 inhibited the rapid recombination of photogenerated electron-hole pairs. This work provides potential insights for the innovative design of high-performance photocatalysts based on metal-organic frameworks for the restoration of Cr(Ⅵ)-containing wastewater.

Fabrication of Z-scheme TiO2/BP/g-C3N4 nanocomposite via pulsed laser ablation in liquid for photocatalytic overall water splitting

Indirect Z-scheme heterostructure photocatalysts possess great potential for simulated light-induced overall water splitting. However, the fabrication of highly-efficient indirect Z-scheme heterostructures under solar light irradiation remains a great challenge. In this work, a novel ternary nanocomposite material comprising of TiO2 nanowires, g-C3N4 nanosheets, and black phosphorous (BP) has been fabricated successfully using pulsed laser ablation technique. A series of characterization techniques were exploited to elucidate the optical, structural, and morphological attributes of the synthesized nanostructure. Under simulated light irradiation, the fabricated TiO2/BP/g-C3N4 nanocomposite displayed stable and efficient photocatalytic overall water splitting performance with hydrogen and oxygen evolution rate of 118.2 and 240 μmol g−1h−1, respectively. The nanocomposite showed an Apparent Quantum Yield (AQY) of 7.8% (400 nm), excellent photocatalytic activity i.e. (≈5.4 times higher than TiO2/BP nanocomposite), and stability. The significant enhancement in the photocatalytic efficiency of the fabricated nanocomposite is attributed to the collective gains arising from the low bandgap, large surface area, and formation of Z-scheme that facilitated charge separation on the TiO2/BP/g-C3N4 nanocomposite.

Core-shell structured Z-scheme Ag2S/AgIO3 composites for photocatalytic organic pollutants degradation

Constructing direct Z-scheme system is a promising strategy to boost the photocatalytic performance for pollution waters restoration, but it is of great challenge because of the requirement of appropriately staggered energy band alignment and intimate interfacial interaction between semiconductors. Herein, a class of core-shell structured Ag2S–AgIO3 Z-scheme heterostructure photocatalysts are designed and developed. Ag2S is generated by the in-situ ion exchange reaction and anchored on the surface of AgIO3, so the intimate interface between AgIO3 and Ag2S is realized. Integration of AgIO3 and Ag2S extends the ultraviolet absorption of AgIO3 to Vis-NIR region, and also promote the charge separation and migration efficiency, contributing to the enhanced photocatalysis activity for composite catalysts. The optimal Ag2S–AgIO4-4 catalyst exhibits a MO photo-degradation rate constant of 0.298 h−1, which reaches 5.77 and 11.4-folds higher than that of AgIO3 (0.044 h−1) and Ag2S (0.024 h−1). The as-obtained composite catalyst exhibits universally photocatalytic activity in disintegrating diverse industrial pollutants and pharmaceuticals. Particularly, driven by natural sunlight, the Ag2S–AgIO4-4 can effectively decompose MO. A plausible Z-scheme photocatalytic mechanism and reaction pathways of MO degradation over composite catalyst are systemically investigated and proposed.

Nanoscale Assembly of CdS/BiVO4 Hybrids for Coupling Selective Fine Chemical Synthesis and Hydrogen Production under Visible Light.

Simultaneously utilizing photogenerated electrons and holes in one photocatalytic system to synthesize value-added chemicals and clean hydrogen (H2) energy meets the development requirements of green chemistry. Herein, we report a binary material of CdS/BiVO4 combining one-dimensional (1D) CdS nanorods (NRs) with two-dimensional (2D) BiVO4 nanosheets (NSs) constructed through a facile electrostatic self-assembly procedure for the selectively photocatalytic oxidation of aromatic alcohols integrated with H2 production, which exhibits significantly enhanced photocatalytic performance. Within 2 h, the conversion of aromatic alcohols over CdS/BiVO4-25 was approximately 9-fold and 40-fold higher than that over pure CdS and BiVO4, respectively. The remarkably improved photoactivity of CdS/BiVO4 hybrids is mainly ascribed to the Z-scheme charge separation mechanism in the 1D/2D heterostructure derived from the interface contact between CdS and BiVO4, which not only facilitates the separation and transfer of charge carriers, but also maintains the strong reducibility of photogenerated electrons and strong oxidizability of photogenerated holes. It is anticipated that this work will further stimulate interest in the rational design of 1D/2D Z-scheme heterostructure photocatalysts for the selective fine chemical synthesis integrated with H2 evolution.