Direct Z-scheme Photocatalyst Research Articles

Direct Z-scheme ZnIn2S4@MoO3 heterojunction for efficient photodegradation of tetracycline hydrochloride under visible light irradiation

It is of great significance to degrade antibiotics contamination by visible-light photocatalysis, however, exploiting photocatalysts with a strong visible light response, high efficiency, and stability remains a major challenge. Herein, a direct Z-scheme photocatalyst based on ZnIn2S4@MoO3 has been obtained, in which ZnIn2S4 nanosheets in-situ grow on MoO3 nanowire. The optimized composite exhibits good catalytic activity for the visible-light-driven degradation of tetracycline hydrochloride (TC-HCl), of which the reaction rate is 25.8 and 7.8 times that of the pristine MoO3 and ZnIn2S4, respectively. The experiment results and density function theory (DFT) calculation revealed that the improved performance could be attributed to the Z-scheme charge transfer mechanism inside of the heterojunction, which can simultaneously mediate the direction of photoinduced charge migration, boost the charge transfer, and maintain the high redox capacity of photogenerated electrons or holes. Moreover, possible TC-HCl degradation routes are also proposed. This work could further motivate the rational design and synthesis of Z-scheme heterojunction photocatalysts for removing antibiotics from the natural environment via visible light irradiation.

Constructing Heterogeneous Direct Z-Scheme Photocatalysts Based on Metal-Organic Cages and Graphitic-C3N4 for High-Efficiency Photocatalytic Water Splitting.

The development of artificial devices that mimic the highly efficient and ingenious photosystems in nature is worthy of in-depth study. A metal-organic cage (MOC) Pd2(M-4)4(BF4)4, denoted as MOC-Q1, integrating four organic photosensitized ligands M-4 and two Pd2+ catalytic centers is designed for a photochemical molecular device (PMD). MOC-Q1 is successfully immobilized on graphitic carbon nitride (g-C3N4) by hydrogen bonds to obtain a robust heterogeneous direct Z-scheme g-C3N4/MOC-Q1 photocatalyst for H2 generation under visible light. The optimized g-C3N4/MOC-Q1 (2 wt %) system shows high hydrogen evolution activity (4495 μmol g-1 h-1 based on the catalyst mass) and exhibits stable performances for 25 h (a turnover number of 19,268 based on MOC-Q1), significantly outperforming pure MOC-Q1, g-C3N4, and comparsion materials Pd/g-C3N4/M-4, which is the highest one of all reported heterogeneous MOC-based photocatalysts under visible irradiation. This enhancement can be ascribed to the synergistic effects of high-efficient electron transfer, extended visible-light response region, and good protective environment for MOC-Q1 arising from an efficient direct Z-scheme heterostructure of g-C3N4/MOC-Q1. This rationally designed and synthesized MOC/g-C3N4-based heterogeneous PMD is expected to have great potential in photocatalytic water splitting.

Construction of direct Z-scheme photocatalyst by the interfacial interaction of WO3 and SiC to enhance the redox activity of electrons and holes

The direct Z-scheme heterojunction structure benefits separation and migration of photoinduced carriers while maintaining original redox ability of each component. Nowadays, most Z-scheme structures are fabricated by g-C3N4 with other narrow band photocatalysts due to its low conduction band (CB). In this paper, SiC, another kind of photoelectric semiconductor with low CB, was employed to prepare direct Z-scheme photocatalyst with 2D WO3 by simple water oxidation precipitation method. The component and interface band structure of Z-scheme heterojunction WO3/SiC (WS) were verified by XPS, KPFM, Mott-Schottky method. The photodegradation efficiency and rate constant values of WS-1 for degrading RhB enhanced 2.5 and 5.3 times respectively compared with pristine WO3. Radical capture experiments and ESR tests affirmed that WS-1 photocatalyst produced •OH and •O2－active species, which further confirmed the photogenerated carriers were transmitted through the Z-scheme mode in principle. Band structure investigation showed that the direct Z-scheme structure assembled by WO3 with high valence band (VB) and SiC with low CB could maintain the high photocatalytic activity of active species. Therefore, this study offers a feasible method for construction of a novel and efficient direct Z-scheme photocatalyst.

Theoretical progress on direct Z-scheme photocatalysis of two-dimensional heterostructures

Two-dimensional (2D) materials, due to its excellent mechanical, unique electrical and optical properties, have become hot materials in the field of photocatalysis. Especially, 2D heterostructures can well inhibit the recombination of photogenerated electrons and holes in photocatalysis because of its special energy band structures and carrier transport characteristics, which are conducive to enhancing photoenergy conversion capacity and improving oxidation and reduction ability, so as to purify pollutants and store energy. In this minireview, we summarize recent theoretical progress in direct Z-scheme photocatalysis of 2D heterostructures, focusing on physical mechanism and improving catalytic efficiency. Current challenges and prospects for 2D direct Z-scheme photocatalysts are discussed as well.

Z-scheme 2D/2D g-C3N4/Sn3O4 heterojunction for enhanced visible-light photocatalytic H2 evolution and degradation of ciprofloxacin

Photocatalytic water splitting for H2 production and antibiotics pollution removals under wide solar spectrum illumination have been broadly investigated. Graphitic carbon nitride (CN) based binary heterogeneous composite is an important component in artificial photosynthesis. In this work, a novel all-solid-state direct Z-scheme photocatalyst based on CN/Sn3O4 heterojunction is successfully synthesized using a simple calcination strategy. Sn3O4 nanosheets were well dispersed on the surface of CN to establish 2D-2D heterostructure. Benefiting from the wide visible light response of Sn3O4 and the facilitated charge transfer from Sn3O4 to CN for the band alignment, CN/Sn3O4 composite exhibits fascinating photocatalytic H2 evolution and ciprofloxacin degradation. In particular, CN/Sn3O4-3 with 3 wt% of Sn3O4 performs the optimum photocatalytic H2 production activity (98.07 μmol·h-1) and the degradation rate constant is about 3.4 times than CN under visible light irradiation. The enhanced photocatalytic performance mainly derived from the fabrication of direct Z-scheme heterojunction, which maximizes the photo redox capacity of composite. This work will provide new insight into the design of 2D photocatalysts with considerable catalytic activity for water splitting and pollutants degradation.

DFT investigation on direct Z-scheme photocatalyst for overall water splitting: MoTe2/BAs van der Waals heterostructure

The photocatalytic efficiency of monolayer materials can be greatly improved by constructing two-dimensional van der Waals heterostructures. In this work, the electronic properties and photocatalytic mechanism of the MoTe2/BAs heterostructure with a stable structure are explored via the density functional theory. According to our results, the heterostructure, with a direct band gap value of 0.70 eV, has an intrinsic type-II band alignment that provides indispensable conditions for photocatalytic applications. The built-in electric field formed at the interface accelerates the reorganization of photogenerated holes in MoTe2 and photogenerated electrons in BAs, which results in the photogenerated electrons and holes in the heterostructure accumulate in CB of MoTe2 and VB of BAs, respectively. The spatial separation of photoexcited electrons and holes prolongs the lifespan of carriers and enhances the photocatalytic efficiency of the MoTe2/BAs heterostructure. Besides, these results demonstrate that the heterostructure possesses higher carrier mobility and a higher light absorption coefficient than two monolayers. The MoTe2/BAs heterostructure also has a remarkable solar-to-hydrogen efficiency. These distinguishing features confirm the truth that the MoTe2/BAs heterostructure has promising prospects in the sphere of photocatalysis for water splitting.

Constructing direct Z-scheme photocatalysts with black N–TiO2-x/C and Cd0.5Zn0.5S for efficient H2 production

Black N doped TiO2-x nanoparticles loaded on the carbon framework (N–TiO2-x/C, NTC) were successfully fabricated by sol-gel method. In this work, the synthesized NTC material was combined with Cd0.5Zn0.5S (ZCS) short nanorods, forming a direct Z-scheme NTC/ZCS photocatalyst without using of electron mediator. The free radicals trapping experiment was also conducted through the degradation of RhB to determine photocatalytic mechanism. As a result, the 2% NTC/ZCS exhibited an optimal photocatalytic H2 production rate which is up to 36.6 mmol/h/g and about 5.2 times higher than that of pristine ZCS nanorods. The apparent quantum efficiency (AQE) of the 2% NTC/ZCS hybrids at wavelength 420 nm was calculated to 51.2%. Moreover, long-term drying increases the close contact between NTC and ZCS, and this firm contact interface can promote charge transfer and improve photocatalytic stability of NTC/ZCS composite.

Construction of direct Z-scheme BPQDs-modified BiOBr thin film for enhanced photocatalytic performance under visible light irradiation

Surface modification on photocatalytic thin films is long considered as an effective strategy to improve the degradation performance, which in turn helps to alleviate the worldwide environmental pollution issue. In this study, a direct Z-scheme photocatalytic system is constructed successfully by integrating black phosphorus quantum dots (BPQDs) on the surface of BiOBr thin film prepared by hydrothermal method. The optimal BPQDs/BiOBr-1 thin film presents remarkable enhanced photocatalytic activity for degrading methyl violet (MV) and tetracycline hydrochloride (TC), which is 3 and 3.65 times higher than that of pure BiOBr counterpart. The active species involved in the reaction are h+, •O2−, and •OH, which determined by radical trapping experiments. The formation of direct Z-scheme photocatalytic system makes electrons assembled in the conduction band (CB) of BPQDs and holes gathered in the valence band (VB) of BiOBr, which supports the generation of h+ and •O2− and in turn accelerates the photocatalytic reaction. Besides, the improved efficiency of charge separation, enhanced visible light absorption and enlarged specific surface area also contributed to the enhanced photocatalytic performance of BPQDs/BiOBr. This work provides a feasible strategy for optimizing photocatalytic thin films via detailed analyzing the role of BPQDs in the construction of direct Z-scheme photocatalysts.

Fabrication of 1D/2D CdS/CoSx direct Z-scheme photocatalyst with enhanced photocatalytic hydrogen evolution performance

In this work, we fabricate a 1D/2D heterojunction photocatalyst composed of n-type CdS nanorods and p-type CoSx nanoflake. This photocatalyst achieves a hydrogen evolution rate of 9.47 mmol g−1 h−1, which is 13.7 times higher than that of pure CdS nanorods. Scanning Kelvin Probe, Mott-Schottky plots, UV–Vis absorption spectra and surface photocarrier orienting reaction results indicate that the enhanced photocatalytic performance of CdS/CoSx is owing to the fabrication of direct Z-Scheme heterojunction system which greatly improves the utilization, migration and separation rate of photo-generated carriers. To the best of our knowledge, this work is the first time to describe a CdS/CoSx direct Z-scheme system with 1D/2D nanostructure, which can expedite the transfer process of photogenerated carriers with strong redox energy to participate in photocatalytic reactions.

MoS2 and Janus (MoSSe) based 2D van der Waals heterostructures: emerging direct Z-scheme photocatalysts.

Two-dimensional (2D) materials, viz. transition metal dichalcogenides (TMD) and transition metal oxides (TMO), offer a platform that allows the creation of heterostructures with a variety of properties. The optoelectronic industry has observed an upheaval in the research arena of MoS2 based van der Waals (vdW) heterostructures (HTSs) and Janus structures. Therefore, interest towards these structures is backed by the ability to select their electronic and optical properties. The present study investigates the photocatalytic abilites of bilayer, MoS2 and Janus (MoSSe) based vdW HTSs, viz. MoS2/TMO, MoS2/TMD, MoSSe/TMO and MoSSe/TMD, by a first-principles based approach under the framework of (hybrid) density functional theory (DFT) and many body perturbation theory (GW approximation). We have considered HfS2, ZrS2, TiS2 and WS2, and HfO2, T-SnO2 and T-PtO2 from the families of TMDs and TMOs, respectively. The photocatalytic properties of these vdW HTSs are thoroughly investigated and compared with their respective individual monolayers by visualizing their band edge alignments, electron–hole recombination and optical properties. Strikingly, we observe that, despite most of the individual monolayers not performing optimally as photocatalysts, type II band edge alignment is noticed in vdW HTSs and they appear to be efficient photocatalysts via the Z-scheme. Moreover, these vdW HTSs have also shown promising optical responses in the visible region. Finally, electron–hole recombination, H2O adsorption and hydrogen evolution reaction (HER) results establish that MoSSe/HfS2, MoSSe/TiS2, MoS2/T-SnO2 and MoSSe/ZrS2 are probable highly efficient Z-scheme photocatalysts.

The construction of a dual direct Z-scheme NiAl LDH/g-C3N4/Ag3PO4 nanocomposite for enhanced photocatalytic oxygen and hydrogen evolution.

Dual direct Z-scheme photocatalysts for overall water decomposition have demonstrated strong redox abilities and the efficient separation of photogenerated electron–hole pairs. Overall water splitting utilizing NiAl-LDH-based binary and ternary nanocomposites has been extensively investigated. The synthesized binary and ternary nanocomposites were characterized via XRD, FTIR, SEM, HRTEM, XPS, UV-DRS, and photoelectrochemical measurements. The surface wettability properties of the prepared nanocomposites were measured via contact angle measurements. The application of the NiAl-LDH/g-C3N4/Ag3PO4 ternary nanocomposite was investigated for photocatalytic overall water splitting under light irradiation. In this work, we found that in the presence of Ag3PO4, the evolution of H2 and O2 is high over LCN30, and 2.8- fold (O2) and 1.4-fold (H2) activity increases can be obtained compared with the use of LCN30 alone. It is proposed that Ag3PO4 is involved in the O2 evolution reaction during water oxidation and g-C3N4 is involved in overall water splitting. Our work not only reports overall water splitting using NiAl-LDH-based nanocomposites but it also provides experimental evidence for understanding the possible reaction process and the mechanism of photocatalytic water splitting. Photoelectrochemical measurements confirmed the better H2 and O2 evolution abilities of NiAl-LDH/g-C3N4/Ag3PO4 in comparison with NiAl LDH, g-C3N4, Ag3PO4, and LCN30. The observed improvement in the gas evolution properties of NiAl LDH in the presence of Ag3PO4 is due to the formation of a dual direct Z-scheme, which allows for the easier and faster separation of charge carriers. More importantly, the LCNAP5 heterostructure shows high levels of H2 and O2 evolution, which are significantly enhanced compared with LCN30 and pure NiAl LDH.

A rationally designed two-dimensional MoSe2/Ti2CO2 heterojunction for photocatalytic overall water splitting: simultaneously suppressing electron-hole recombination and photocorrosion.

Electron–hole recombination and photocorrosion are two challenges that seriously limit the application of two-dimensional (2D) transition metal dichalcogenides (TMDs) for photocatalytic water splitting. In this work, we propose a 2D van der Waals MoSe2/Ti2CO2 heterojunction that features promising resistance to both electron–hole recombination and photocorrosion existing in TMDs. By means of first-principles calculations, the MoSe2/Ti2CO2 heterojunction is demonstrated to be a direct Z-scheme photocatalyst for overall water splitting with MoSe2 and Ti2CO2 serving as photocatalysts for hydrogen and oxygen evolution reactions, respectively, which is beneficial to electron–hole separation. The ultrafast migration of photo-generated holes from MoSe2 to Ti2CO2 as well as the anti-photocorrosion ability of Ti2CO2 are responsible for photocatalytic stability. This heterojunction is experimentally reachable and exhibits a high solar-to-hydrogen efficiency of 12%. The strategy proposed here paves the way for developing 2D photocatalysts for water splitting with high performance and stability in experiments.

Design of a noble-metal-free direct Z-scheme photocatalyst for overall water splitting based on a SnC/SnSSe van der Waals heterostructure.

Semiconductor photocatalysts, using sunlight to stimulate various photocatalytic reactions, are promising materials for solving the energy crisis and environmental problems. However, the low photocatalytic efficiency and high cost pose major challenges for their widespread application. Mimicking the natural photosynthesis system, we propose a direct Z-scheme photocatalyst based on a Janus van der Waals heterostructure (vdWH) comprising SnC and Janus SeSnS monolayers. From first-principles calculations, the intrinsic built-in electric field of Janus SeSnS and the charge transfer from the SnC to the SeSnS layer give rise to a type-II band alignment. Such a band alignment benefits the formation of spatially separated reductive and oxidative active sites and the reduction of the global bandgap of the Janus vdWH. The proposed material increases the solar-to-hydrogen conversion efficiency to 60.8%. Besides, we also find that the light absorption coefficient is stacking configuration controllable and strain-tunable, e.g., the tensile strain promotes photocatalytic efficiency. Moreover, because Sn, S, and Se are environmentally benign and inexpensive elements, SnC/SeSnS vdWH is a promising noble-metal-free direct Z-scheme photocatalyst.

Hierarchical CoTiO3@NiO core–shell sub-microbelts as direct Z-scheme photocatalyst for efficient visible-light-driven tetracycline degradation

The hierarchical binary 1D@2D CoTiO3@NiO Z-scheme heterojunctions with well-defined core–shell feature display the enhanced photocatalytic activity for antibiotic tetracycline decomposition under visible light illumination. The obtained CoTiO3@NiO heterostructured sub-microbelts show a superior photocatalytic efficiency to the pristine CoTiO3 sub-microbelts, and NiO nanoclusters. The TC removal efficiency of CoTiO3@NiO sub-microbelts is 1.75 and 2.15 times higher than that of pristine CoTiO3, and NiO, respectively. The electrospinning CoTiO3 sub-microbelts are decorated uniformly with in situ nanosheets of NiO longitudinally aligned through a facile two-step precipitation-calcination processure. The Z-scheme heterojunctions consisting of CoTiO3 and NiO efficiently accelerate photo-generated electron-hole separation efficiency, and afford a high specific surface area, which ultimately improve the efficiency of TC degradation. The profitable carrier transmission mechanism and special core–shell structure in the CoTiO3@NiO system are in charge of the elevated catalytic activity because of the formed Z-scheme system. These features demonstrate that the hierarchical CoTiO3@NiO core–shell heterojunctions have the great application potential for tetracycline removal from wastewater.

Bilayer MoTe2/XS2 (X = Hf,Sn,Zr) heterostructures with efficient carrier separation and light absorption for photocatalytic water splitting into hydrogen

The photocatalytic water splitting to produce hydrogen has been extensively investigated as one of the most promising means for solving the global energy crisis and environmental problem. In this work, we have designed bilayer two dimensional (2D) van der Waals (vdW) MoTe2/XS2 (X = Hf,Sn,Zr) heterostructures and studied their electronic, optical properties and photocatalytic activities. According to the hybrid density functional computations, these heterojunctions have been found to be stable and potential candidates for direct Z-scheme photocatalysts, where MoTe2 and XS2 layers can be used for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Compared with the MoTe2 and XS2 monolayers, MoTe2/XS2 (X = Hf,Sn,Zr) heterostructures with internal electric fields can achieve high-efficiency carriers separation. Meanwhile, these nanocomposites with narrower bandgaps are able to make the best of the sunlight even in the visible light (VIS) region, which is good for enhancing the photocatalytic performance. Therefore, these results have paved the way for exploring efficient MoTe2-based photocatalysts for overall water splitting.

Tunable charge transfer efficiency in HxMoO3@ZnIn2S4 hierarchical direct Z-scheme heterojunction toward efficient visible-light-driven hydrogen evolution

A Z-scheme system is ideal for photocatalysis hydrogen evolution due to spatially separating photogenerated electron–hole pairs and strong redox ability. However, the construction of such a system to achieve rapid charge transfer is still a big challenge. Hierarchical functional nanomaterials with controllable morphology, dimensionality, and electronic property can open more possibilities for designing active Z-scheme photocatalysts. Herein, we construct hierarchical direct Z-scheme composites of epitaxial ultrathin ZnIn2S4 nanosheets on HxMoO3 nanobelts, which exhibits 10.5 times higher H2-production activity (5.9 mmol·g−1·h−1) than pristine ZnIn2S4 with visible light. High conductivity and tunable charge transfer efficiency of HxMoO3 component resulting from hydrogen intercalation are favourable to the effective transport of charge carriers. Moreover, hierarchical architecture composed of 2D nanosheets increases intimate interface for effective separation of electron–hole pairs and exposes more reactive sites. The study provides a new sight in designing hierarchical direct Z-scheme photocatalyst for solar fuel generation.

In-situ constructing of one-dimensional SnIn4S8-CdS core-shell heterostructure as a direct Z-scheme photocatalyst with enhanced photocatalytic oxidation and reduction capabilities

Incorporating heterojunctions and constructing structures are reliable strategies to solve the problem of inefficient intrinsic charge generation in semiconductors. In this study, a direct Z-scheme heterojunction was formed ingeniously, via the intimate coaxial contact of SnIn4S8-CdS (SISCS) core-shell nanostructure. The prepared core-shell SISCS composites exhibited more superior photocatalytic oxidation and reduction capabilities in comparison with bare CdS and SnIn4S8. Significantly, the SISCS2 sample could reduce 98.9% of Cr (VI) (20 mg/L) and degrade almost all methyl orange (MO) (15 mg/L) within 24 min. The apparent rate constants of Cr (VI) and MO photodegradation over SISCS2 were 3.52 and 7.52 times than those of bare CdS nanorods, 4.57 and 5.59 folds as those of pure SnIn4S8, respectively. The intimate coaxial contact between CdS and SnIn4S8 efficiently enhanced the charge transfer, and the redox ability of the CdS and SnIn4S8 could be maintained crediting to the Z-scheme system heterojunction. Moreover, the enlarged specific surface area and the super-hydrophilic surface could both ensure excellent photocatalytic activity of SISCS composites. Furthermore, the Z-Scheme photocatalytic mechanism and the degradation pathways of MO were also discussed in depth.

Novel 2D/2D BiOBr/UMOFNs direct Z-scheme photocatalyst for efficient phenol degradation

A novel 2D/2D BiOBr/ultrathin metal-organic framework nanosheets (UMOFNs) direct Z-scheme photocatalyst was successfully synthesized by using a simple deposition-precipitation method. The photocatalytic performance was evaluated under light irradiation, which revealed that the 2D/2D BiOBr/UMOFNs Z-scheme photocatalyst exhibits higher photocatalytic degradation of phenol compared to pristine BiOBr and UMOFNs. A BiOBr/UMOFNs-40% (mass ratio for BiOBr and UMOFNs of 1:0.4) photocatalyst was found to show the best photocatalytic degradation efficiency and stability, reaching 99% phenol degradation under light irradiation of 270 min and maintaining 97% degradation after 5 recycling runs. Results obtained from a trapping experiment and electron paramagnetic resonance suggest that reactive ·OH and O2 ·− play a major role in phenol degradation. Photoluminescence and photocurrent results reveal that the excellent photocatalytic activity of the 2D/2D BiOBr/UMOFNs photocatalyst can be ascribed to the efficient separation of photogenerated electron−hole pairs through a direct Z-scheme system. This article provides a possible reference for designing Z-scheme photocatalysts by using MOFs and semiconductors for practical organic pollutant treatment.

Oxalate enhanced synergistic removal of chromium(VI) and arsenic(III) over ZnFe2O4/g-C3N4: Z-scheme charge transfer pathway and photo-Fenton like reaction

In this work, direct Z-Scheme photocatalyst (ZnFe2O4/g-C3N4) was employed to purify Cr(VI) and As(III) in wastewater. Results showed that Cr(VI) and As(III) was completely removed in a wide pH range of 3–7 under visible light irradiation. During photo reaction, oxalate enhanced the generation of Fe(II) and CO2−, which were beneficial for formation of OH and O2−. In photocatalytic system, Fe(II), photogenerated electron, as well as CO2− contributed to Cr(VI) reduction, OH and O2− were responsible for treatment of As(III). Moreover, ZnFe2O4/g-C3N4 was easily recycled by magnetic separation, and presented an excellent reuse ability in treatment of Cr(VI) and As(III).

Ag2S quantum-dot-modified flower-like PbBiO2Br for enhanced photocatalytic degradation of crystal violet

Novel Ag2S/PbBiO2Br (Ag2S/PBOB) direct Z-scheme photocatalysts were successfully synthesized for the first time by modifying flower-like PBOB with Ag2S QDs through a hydrothermal and ion-exchange way. The crystal structure, surface state, morphology, element distribution, electrochemical and optical properties of the as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), photocurrent testing, Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence (PL) technique. The obtained samples were evaluated via degradation of crystal violet (CV) under visible light irradiation. The results show that direct Z-scheme heterojunctions are formed on the interfaces between Ag2S and the PBOB, which enhance the visible light absorbance and efficient separation of photo-generated electron–hole pairs. Moreover, the 5wt%Ag2S/PBOB composite displays the highest photocatalytic activity for the degradation of CV under visible light, where the CV degradation rate is 94.4%, about 1.37 times higher than that for bare PBOB under visible light irradiation for 60 min. The enhanced photocatalytic activity of the Ag2S/PBOB composites can be attributed to strong visible light absorbance and the direct Z-scheme charge transfer mechanism. Moreover, the 5wt%Ag2S/PBOB composite also has a good stability and recyclability and has great potential in environmental protection. In addition, active species trapping experiments confirm that ·O2 and ·OH play a very important role in the degradation process. This work provides new insights and opportunities for establishing photocatalytic models in degradation of organic contaminant.