Separation Of Photoexcited Carriers Research Articles

Nanoengineering construction of g-C3N4/Bi2WO6 S-scheme heterojunctions for cooperative enhanced photocatalytic CO2 reduction and pollutant degradation

S-scheme heterojunction photocatalysts featuring efficient charge transport paths provide a promising strategy for cooperative achieving photocatalytic CO2 reduction reaction (CO2RR) and Rhodamine B (RhB) degradation. In this work, S-scheme heterojunctions composed of g-C3N4 nanosheets coated on Bi2WO6 nanosheets were prepared by a one-step hydrothermal method, resulting in broad-spectrum light absorption, high electron–hole separation efficiency, and excellent photocatalytic CO2 reduction and RhB oxidization performance. Mechanistic analysis revealed the formation of a directional charge transport path at the interface of the heterojunction, which maintained a high oxidation and reduction potential and improved the efficiency of photoexcited carrier separation. In particular, the synergistic reaction system showed excellent photoredox activity compared with the two separate half-reactions. The optimal catalyst 15CN/BWO displayed the highest CO2 conversion efficiency, with CO and CH4 generation rates of 4.3 and 2.7 μmol g−1h−1, respectively, and the degradation efficiency of the composite heterojunction was significantly higher than that of its constituent materials. This work provides a new possibility for designing a novel dual-function photocatalytic reaction system.

In situ construction of core-shell NiFe-LDH@ZnIn2S4 direct Z-scheme heterojunction for facilitating photocatalytic H2 evolution

The development of photocatalysts with non-noble metals and the effective separation of photoexcited carriers is a significant strategy for accelerating surface reaction kinetics and promoting water splitting to produce H2. Herein, an exquisite core-shell NiFe-LDH@ZnIn2S4 heterojunction photocatalyst was constructed by in situ decoration of ultrathin ZnIn2S4 nanosheets on the surface of the flower-like NiFe-LDH microsphere. The synthesized 3D hierarchical NiFe@ZIS-25 composite exhibits enhanced photocatalytic H2 evolution activity, reaching 9.12 mmol·h-1·g-1, which is 2.52-fold higher than pure ZnIn2S4. The significant improvement in H2 evolution performance could be attributed to the hierarchical core-shell structure of the NiFe@ZIS-25 photocatalyst, which enhanced the light capture ability. In addition, the interfacial coupling effect of ZnIn2S4 and NiFe-LDH is beneficial to the migration of carriers. More importantly, the construction of Z-scheme heterojunction efficiently promotes the fast translation of photogenerated carriers while preserving a stronger reduction potential to achieve H2 evolution. This work elucidates a rational strategy to develop efficient photocatalysts with hierarchical core-shell structures for water splitting.

Engineering oxygen vacancies and morphology of BiOCl microspheres via electrification to enhance visible light photocatalytic performance

Enhancing the separation efficiency of photo-generated carriers and the surface area of catalysts is beneficial to improve the photocatalytic performance, which is critical to achieving application of photocatalysis in practical environmental remediation. In this work, the BiOCl microspheres were treated with electrification for the first time to synergistically tune oxygen vacancies (OVs) and microstructure. With 6 h electrification, the photocatalytic performance of BiOCl-6 microspheres was significantly enhanced, which can not only degrade organic contaminants, but also effectively reduce toxic heavy metal ions. The photocatalytic reaction rates for methyl blue (MB), ciprofloxacin (CIP) and hexavalent chromium Cr(VI) reached 0.071, 0.056 and 0.097 min−1, respectively, which were 5.1, 7.0 and 8.1 times higher than that of pristine BiOCl. The density functional theory (DFT) calculations and experimental investigation suggest that the designed OVs facilitates the separation of photo-excited carriers and expands the light adsorption range of BiOCl. Meanwhile, the increased surface area of BiOCl-6 microspheres enhances the adsorption for contaminants and provides more active sites for photocatalytic reaction. This work provides a new approach to synergistically enhance photocatalytic performance for photocatalysts by vacancy engineering and morphology control.

Enhanced photocatalytic degradation of organic pollutants in actual sewage water with a full-spectrum-responsive NaYF4:Yb,Tm@NaYF4:Yb,Nd@TiO2@g-C3N4 nanoheterojunction photocatalyst

Full spectrum-excitation photocatalysis is promising for the environmentally friendly treatment of actual sewage with sunlight. High-efficiency, stable NaYF4:Yb,Tm@NaYF4:Yb,Nd@TiO2@g-C3N4 (UPTC) nanoheterojunction photocatalysts were fabricated via facile chemical synthesis. Nanophotocatalyst characterization revealed good crystallinity, strong composite formation, and a high separation rate of photoexcited charges. The synthesized UPTC was excited by ultraviolet, visible light and infrared light, exhibiting excellent full spectrum-response. Under near-infrared irradiation at 808 nm and 980 nm, UPTC effectively degraded rhodamine B (RhB). Under simulated sunlight, UPTC decomposed 88.6% malachite green, 92.2% rose bengal, and 90.8% RhB in 90 min. In photocatalysis, ·O2- played a dominant role. Moreover, the nanoheterojunction structure greatly improved photoexcited carrier separation. UPTC nanoheterojunction had excellent recycling capability. In actual sewage treatment, UPTC degraded 36.5% ammonia-nitrogen under simulated sunlight. In addition, UPTC exhibited sufficient biosafety. This study offers a fresh potential approach for producing highly efficient, stable, and biosafe nanoheterojunction photocatalysts for sewage treatment.

Dissolved oxygen enhanced piezo-photocatalytic performance in Ag dots-modified BaTiO3 nanoparticles for efficient degradation of multiple organic pollutants

Piezoelectric nanomaterials have attracted much attention due to their ability to modulate photo-excited carrier separation and migration under strain. Perovskite-structured BaTiO3 (BT) is a promising piezo-photocatalytic material due to its high piezoelectric coefficient and special phase structure. In this work, a series of x wt.% Ag/BT composites prepared by a two-step approach were developed for piezo-photocatalysis applications. The 0.8 wt.% Ag/BT showed an excellent piezo-photocatalytic performance for degrading 75.8 % Rhodamine B (RhB) in 60 min. Especially, the catalytic performances were strongly correlated with the atmosphere conditions of the catalyst. The piezo-photodegradation rate of RhB by 0.8 wt.% Ag/BT under O2 atmosphere reached 95.7 % in 40 min, and the first order kinetic rate constant (k) reached 0.06759 min−1, which was 9.9 and 2.4 times that of N2 and air condition, respectively. The Density functional theory (DFT) calculations further revealed that dissolved oxygen could enhance the material's adsorption of RhB. Compared with hydroxyl free radicals (OH) and holes (h+), superoxide radicals (O2–) play an indispensable role in the catalytic process through the trapping experiments and ESR analyses. Furthermore, the RhB degradation pathway and potential ecotoxicity were also proposed. This work is hoped to provide an understanding the mechanism of piezo-photocatalysis and bring new ideas for the development of piezo-photocatalysis catalysis for multifunctional environmental applications.

Insight into the synergic charge transfer on S − Mo bond-modified Z-scheme MgIn2S4/MoSe2 towards norfloxacin degradation: Mechanism, pathways and toxicity evaluation

In the semiconductor photocatalysis on heterojunctions, the charge transfer path and concomitant interfacial resistance greatly affect the carrier separation efficiency and the overall photocatalytic performance. Herein, a novel S–Mo bonded Z-scheme heterojunction of MgIn2S4/MoSe2 was successfully synthesized by a facile hydrothermal method. The photocatalytic activities on the covalently bonded MgIn2S4/MoSe2 were assessed using the norfloxacin, a typical fluoroquinolone antibiotic, under visible light. The Z-scheme charge transfer route was proposed and investigated by combining quenching tests, ESR spectroscopy and DFT calculations. Furthermore, the establishment of SMo bonds between MgIn2S4 and MoSe2 was verified via experimental characterizations and theoretical simulation. This chemical SMo linkage, acting as a distinct bridge, in collaboration with the Z-scheme charge migration path synergistically promoted the transport and separation of photo-excited carriers, leading to a remarkable enhancement in the norfloxacin decomposition. Additionally, the potential degradation pathways of NOF were proposed via a complementary utilization of mass spectrometry and DFT techniques. Lastly, the computational toxicology predicted that the majority of the byproducts derived from norfloxacin degradation exhibited a progressive reduction in toxicity.

A Robust Pyro-phototronic Route to Markedly Enhanced Photocatalytic Disinfection.

Photocatalysis offers a direct, yet robust, approach to eradicate pathogenic bacteria. However, the practical implementation of photocatalytic disinfection faces a significant challenge due to low-efficiency photogenerated carrier separation and transfer. Here, we present an effective approach to improve photocatalytic disinfection performance by exploiting the pyro-phototronic effect through a synergistic combination of pyroelectric properties and photocatalytic processes. A set of comprehensive studies reveals that the temperature fluctuation-induced pyroelectric field promotes photoexcited carrier separation and transfer and thus facilitates the generation of reactive oxygen species and ultimately enhances photocatalytic disinfection performance. It is worth highlighting that the constructed film demonstrated an exceptional antibacterial efficiency exceeding 95% against pathogenic bacteria under temperature fluctuations and light irradiation. Moreover, the versatile modulation role of the pyro-phototronic effect in boosting photocatalytic disinfection was corroborated. This work paves the way for improving photocatalytic disinfection efficiency by harnessing the synergistic potential of various inherent material properties.

Mediation of Interfacial Mo2C Bridging Effect in MoS2@Carbon Colloid Dots Featuring Improved Photovoltaic Performances of Si‐Based Hybrid Solar Cells

AbstractAdvances in silicon‐based hybrid solar cells with high photovoltaic performance, low synthetic cost, and sound environmental resistance are emerged as potential candidate for solar conversion. Solution‐processed few‐layer MoS2 sheets are regarded as compelling constitutes that paves ways for tailoring the solar harvesting capability; yet the improvement on charge separation of photoexcited carriers remains demanded, and the lack of environmental stability due to intentionally grabbing electrons from adsorbed moistures constrains the scope of practical assessment. In this work, the employment of MoS2/Mo2C/carbon colloid dots (CCDs) heterostructures within PEDOT:PSS matrix is invoked, where the transfer of photoexcited electrons from MoS2 is mediated with Mo2C electron‐transport channels, which further couple out the creation of positive trions by combining with defect‐bound excitons at CCD surfaces. These features dynamically involve with slow recombination probability and further improve the photovoltaic gain. Thus, the noticeable improvement of conversion efficiency of 16.1% with 1.6 times of efficiency enhancement outperforming the bare conventional hybrid solar cells is accomplished, and further exhibits a sound long‐term stability, which opens new avenues for exploiting the photophysical bound‐carrier transition on advanced photovoltaic applications.

Precise Lattice‐Strain Modulation of Hematite Enabled by Gradient Doping of Mn for Enhanced Photoelectrocatalytic Oxidative C─C Bond Scission

The high‐value utilization of biomass feedstock is fascinating but limited by efficient C─H activation to break C─C bonds. Herein, F‐Fe2O3‐Mn photoanodes with modulable compressive strain are fabricated by gradient infusion of Mn into F‐doped hematite (F‐Fe2O3), which is illustrated to be highly efficient for oxidative C─C bond cleavage of various bio‐based 1,2‐diols to produce benzoic acids or aromatic ketones (94.5–97.2% yields) in photoelectrocatalytic (PEC) device, coupling with a high H2 production of 1180 μmol cm−2 (≈96% yield). The gradient doping of Mn species into the photoelectrode bulk results in improved photoexcited carriers separation and transfer efficiency of the photoelectrode (3.41 mA cm−2). On the other hand, the lattice distortion induced by Mn doping also leads to a strain effect on F─Fe2O3─Mn, which can precisely modulate the photoelectrode electronic structure. Control experiments, in situ characterization, and theoretical calculations elaborate that compressive strain is capable of adjusting the position of the d‐band center to facilitate C─H activation, remarkably enabling PEC oxidative C─C bond breaking of 1,2‐diol and the desorption of the oxidized product. This “one‐stone‐two‐bird” strategy presents a straightforward protocol for efficiently breaking C─C bonds in organic and biomass transformations via PEC oxidation.

S-induced Phase Change Forming In2 O3 /In2 S3 Heterostructure for Photoelectrochemical Glucose Sensor.

In the past several decades, Photoelectrochemical (PEC) sensing still remains a great challenge to design highly-efficient semiconductor photocatalysts via a facile method. It is of much importance to design and synthesize various novel nanostructured sensing materials for further improving the response performance. Herein, we present an In2 O3 /In2 S3 heterostructure obtained by combining microwave assisted hydrothermal method with S-induced phase change, whose energy band and electronic structure could be adjusted by changing the S content. Combining theoretical calculation and spectroscopic techniques, the introduction of sulfur was proved to produce multifunctional interfaces, inducing the change of phase, oxygen vacancies and band gap, which accelerates the separation of photoexcited carriers and reduces their recombination, improving the electronic injection efficiency around the interface of In2 O3 /In2 S3 . As anticipated, an enhanced glucose response performance with a photocurrent of 0.6 mA cm-2 , a linear range of 0.1-1 mM and a detection limit as low as 14.5 μM has been achieved based on the In2 O3 /In2 S3 heterostructure, which is significant superior over its pure In2 O3 and S-doped In2 O3 counterparts. This efficient interfacial strategy may open a new route to manipulate the electrical structure, and energy band structure regulation of sensing material to improve the performance of photoelectrodes for PEC.

Efficient charge separation and improved photoelectric properties of GaN/WS2/MoS2 heterojunction: A molecular dynamics simulations

Utilizing the stacking of two-dimensional (2D) materials to fabricate heterojunction represents an exceedingly effective approach for designing high-performance optoelectronic devices. In this paper, the GaN/WS2/MoS2 heterojunction was systematically studied using DFT calculations. The interface effect caused the effective separation of photo-excited carriers in the GaN/WS2/MoS2 heterojunction by inducing a stepwise transfer of the carriers, forming a build-in electric field. Due to the decrease in bandgap, the heterojunction exhibited enhanced light absorption ability across the entire spectral region. Especially, the carrier recombination time reached the microsecond level, greatly extending the lifetime of photo-excited carriers and effectively improving the energy conversion performance of photodetectors. Moreover, the augmentation of tensile strain enhances both the self-powering capacity and the near-infrared light detection capability of the GaN/WS2/MoS2 heterojunction. The exceptional performances exhibited by the GaN/WS2/MoS2 heterojunction make it a highly up-and-coming candidate for optoelectronics application.

Construction of co-zeolitic imidazolate framework/Bi2WO6 heterojunction photocatalyst with improved adsorption and photodegradation of ciprofloxacin

Refractory pharmaceutical pollutants have become a serious and formidable threat to both human health and the ecosystem. Photocatalysis presents an intriguing approach of using visible light to break down these environmental contaminants directly. Nevertheless, this technique is plagued by a fast combination of the photogenerated charges, which results in poor efficiency and instability. In this work, a novel ZIF-67/Bi2WO6 heterojunction photocatalyst has been developed as an efficient photocatalyst for ciprofloxacin (CIP) degradation under visible-light irradiation. The obtained ZIF-67/Bi2WO6 Z-type heterojunction exhibit dramatically improved visible-light-driven photocatalytic performance compared to pure ZIF-67 and Bi2WO6. Particularly, ZIF-67/Bi2WO6 shows the highest photocatalytic efficiency for the decomposition of CIP, achieving 91.5 %, at 10 mg/L in 90 min. The enhanced photocatalytic performance is attributed to the Z-type heterostructure with strong visible light absorption and effective separation of photoexcited carriers. The scavengers' studies showed that •O2– and •OH radicals have the most effect on the decomposition process. Besides, ZIF-67/Bi2WO6 is endowed excellent durability and stability. Thus, this work shows that ZIF-67/Bi2WO6 may reveal a promising potential for the degradation of several refractory pharmaceutical contaminants.

Dual-Functional S-Scheme Fe3O4/TiO2/g-C3N4 double-heterostructure bridged by TiO2 for collaborative removal of U(VI) and Sb(III)

Exploiting dual-functional photocatalysts to reduce U(VI) and oxidize Sb(III) is a challenging but efficient way of achieving simultaneous purification. Herein, Fe3O4/TiO2/g-C3N4 (FTC) double-heterostructures with customized stacking order were designed as a dual-functional photocatalyst to collaborative remove U(VI) and Sb(III). When introducing TiO2/g-C3N4 heterojunction and bridging it with Fe3O4/TiO2 using TiO2 as the intermediate layer, FTC showed outstanding photocatalytic activity and can simultaneously achieve 96.5% U(VI) reduction and 88.5% Sb(III) oxidation under sunlight, achieving 90.9% and 85.8% in natural wastewater. The constructed FTC architecture of an S-scheme framework can achieve efficient co-removals of U(VI) and Sb(III) by enhancing the separation and transferal of photoexcited charge carriers with outstanding redox ability employing different reaction sites. TiO2 and g-C3N4 accumulated electrons and holes, respectively, and completed concurrent redox reactions, following the path determined by N(g−C3N4) and O(TiO2), which enhanced the separation of photoexcited carriers. The two-way effect of O2• ⁻ activated by FTC supported positive feedback coupling relationships between the reduction of U(VI) and Sb(III) oxidation. This study not only fulfills the co-removal of U(VI) and Sb (III) for the first time with a capacity of 170.6 and 15.9 mg/g in engineering applications, but also proposes the reaction mechanism of a two-step continuous concerted redox reaction causing high removal determined by the electronic structure, so it lays a foundation for further development of highly efficient and stable heterojunction photocatalysts with concerted effects applied in complex wastewater treatment.

Ultrasensitive photodetector based on 2D WS2/AgInGaS quantum dots heterojunction with interfacial charge transfer

Tungsten disulfide (WS2), as a typical member of transition metal chalcogenides (TMDs), has attracted extensive research interest in optoelectronics, especially photodetectors. However, the performance of photodetectors based on monolayer WS2 is restricted to weak light absorption. Here, AgInGaS quantum dots (AIGS-QDs) with a large absorption coefficient and high quantum efficiency are integrated onto WS2 atomic layers to achieve excellent photoelectric performance. Notably, the observed photoluminescence (PL) quenching and the reduction of the decay time of PL in the WS2/AIGS-QDs heterojunction confirm the interfacial charge transfer from AIGS-QDs to WS2 layer. The results show that type II energy band arrangement leads to the efficient separation of photoexcited carriers at the interface between WS2 and AIGS-QDs. This WS2/AIGS-QDs photodetector achieves an ultrahigh responsivity (R) of 3.3 × 103 A W−1, an external quantum efficiency (EQE) of 7.8 × 106% and a detectivity (D*) of 1.3 × 1013 Jones. Our work provides promising potential for future high-performance monolayer TMD-based photodetectors.

Construction of Z-scheme W18O49/NiAl-LDH heterojunction with photothermal effect for photocatalytic reduction of CO2

Recently, the photocatalytic CO2 reduction technology is an effective solution to remit the energy crisis. In order to improve the photocatalytic performance, Z-scheme W18O49/NiAl-LDH composite catalysts were prepared by hydrothermal method. Fortunately, the prepared catalysts revealed excellent photocatalytic performance under the simulated sunlight, and CO and CH4 could be detected in the reduction products. WO/LDH-0.5 catalyst possessed the optimal activity, with CO and CH4 yield of 37.09 and 8.01 µmol g-1h−1 separately, which were 7.9 and 3.6 times that of NiAl-LDH monomer. In addition, W18O49 endowed W18O49/NiAl-LDH catalysts with photothermal effect, which raised the surface temperature and facilitated the catalytic reaction. Meanwhile, the Z-scheme heterojunction composed of flower-like NiAl-LDH and urchin-like W18O49 accelerated the separation of photoexcited carriers and enhanced the redox ability. Through a series of characterizations and investigations, this work is promising to break new ground for the design of photocatalysts with photothermal effect.

Enhanced photocatalytic performance of persimmon cake like oxygen vacancies enriched NiO/BiVO4 heterojunctions benefited from S-scheme interfacial charge pairs separation and transfer mechanism

Photocatalytic activity of the designed hetero-structured photocatalysts depends largely on the charge pairs transfer efficiency at the interface between the different components. Herein, NiO/BiVO4 heterojunction photocatalysts were in-situ prepared using a one-pot hydrothermal method. Various techniques were used to ascertain the impact of heterogeneous structures and oxygen vacancies (OVs) on the light absorption range, energy band structure, and photogenerated carriers separation behavior of NiO/BiVO4 heterojunctions. It is found that the tight contact interfaces between NiO and BiVO4 and the establishment of internal electric field (IEF) largely promote the effective spatial separation of photoinduced carriers. OVs facilitate molecular oxygen activation and serve as reactive sites to capture photoinduced electrons, promoting the formation of ·O2–. The separation of photoexcited carriers by heterojunctions and the optimization of the material energy band structure by OVs together enhance the photocatalytic activity of the catalysts. Under simulated sunlight irradiation and employing Cr(VI) as a simulated contaminant, photocatalytic performance of the synthesized catalysts was investigated. Photocatalytic reduction rate constant of Cr(VI) on NiO/BiVO4 with 2% mass ratio of Ni/Bi is found to be 15.5 times of that on the blank BiVO4. Photocatalytic activity of the catalyst was demonstrated through treatment of distillery wastewater, which confirms its strong ability to effectively photocatalytic degrade organic substances. Photoinduced charge pairs separation mechanism for enhanced photocatalytic performance of NiO/BiVO4 heterojunction was explored based on experimental observations.

Small-Molecule Probe-Induced In Situ-Sensitized Photoelectrochemical Biosensor for Monitoring α-Glucosidase Activity.

Semiconductor-based photoelectrochemical (PEC) biosensors have garnered significant attention in the field of disease diagnosis and treatment. However, the recognition units of these biosensors are mainly limited to bioactive macromolecules, which hinder the photoelectric response due to their insulating characteristics. In this study, we develop an in situ-sensitized strategy that utilizes a small-molecule probe at the interface of the photoelectrode to accurately detect α-glucosidase (α-Glu) activity. Silane, a prototype small-molecule probe, was surface-modified on graphitic carbon nitride to generate Si nanoparticles upon reacting with hydroquinone, the enzymatic product of α-Glu. The in situ formed heterojunction enhances the light-harvesting property and photoexcited carrier separation efficiency. As a result, the in situ-sensitized PEC biosensor demonstrates excellent accuracy, a low detection limit, and outstanding anti-interference ability, showing good applicability in evaluating α-Glu activity and its inhibitors in human serum samples. This novel in situ sensitization approach using small-molecule probes opens up new avenues for developing simple and efficient PEC biosensing platforms by replacing conventional biorecognition elements.

Dual-Functional Z-Scheme TiO2 @MoS2 @NC Multi-Heterostructures for Photo-Driving Ultrafast Sodium Ion Storage.

Exploiting dual-functional photoelectrodes to harvest and store solar energy is a challenging but efficient way for achieving renewable energy utilization. Herein, multi-heterostructures consisting of N-doped carbon coated MoS2 nanosheets supported by tubular TiO2 with photoelectric conversion and electronic transfer interfaces are designed. When a photo sodium ion battery (photo-SIB) is assembled based on the heterostructures, its capacity increases to 399.3 mAh g-1 with a high photo-conversion efficiency of 0.71 % switching from dark to visible light at 2.0 A g-1 . Remarkably, the photo-SIB can be recharged by light only, with a striking capacity of 231.4 mAh g-1 . Experimental and theoretical results suggest that the proposed multi-heterostructures can enhance charge transfer kinetics, maintain structural stability, and facilitate the separation of photo-excited carriers. This work presents a new strategy to design dual-functional photoelectrodes for efficient use of solar energy.

Enhanced photocatalytic activity and mechanism insight of copper-modulated lead-free Cs2AgSbCl6 double perovskite microcrystals

Lead halide perovskites are prospective candidates for CO2 photoconversion. Herein, we report copper-doped lead-free Cs2AgSbCl6 double perovskite microcrystals (MCs) for gas-solid phase photocatalytic CO2 reduction. The 0.2Cu@Cs2AgSbCl6 double perovskite MCs display unprecedented CO2 photoreduction capability with CO and CH4 yields of 412 and 128μmol g-1, respectively. The ultrafast transient absorption spectroscopy reveals the enhanced separation of photoexcited carriers in copper-doped Cs2AgSbCl6 MCs. The active sites and reaction intermediates on the surface of the doped Cs2AgSbCl6 are dynamically monitored and precisely unraveled based on the in-situ Fourier transform infrared spectroscopy investigation. In combination with density functional theory calculations, it is revealed that the copper-doped Cs2AgSbCl6 MCs facilitate sturdy CO2 adsorption and activation and strikingly enhance the photocatalytic performance. This work offers an in-depth interpretation of the photocatalytic mechanism of Cs2AgSbCl6 doped with copper, which may provide guidance for future design of high-performance photocatalysts for solar fuel production.

CuS Nanoparticles Modified ZnO/CdS Dual Direct Z-type Heterostructure Nanocomposite for Efficient Visible-Light Photocatalytic Degradation RhB

The low-temperature hydrothermal and water bath methods are used to manufacture CuS@ZnO/CdS catalyst. The Rhodamine B degradation rate constant of CuS@ZnO/CdS is around 1.53 × 10−2 min−1, which is 3.9 times greater than that of ZnO. The coupling of CdS and loading of CuS onto ZnO surfaces were evaluated using XRD, SEM, TEM, and XPS. SEM demonstrated that 5 mg of CdS was the most effective in controlling the shape of ZnO nanoflakes. Ultraviolet-visible absorption (UV–vis) and Photoluminescence (PL) spectra reveal that CdS and CuS decreased the bandgap of ZnO and boosted its ability to absorb visible light. Transient photocurrent response (TPR) and electrochemical impedance spectra (EIS) display that CdS and CuS facilitate the quick separation of photoexcited carriers in ZnO. Notably, the optimal weight ratio of CuS was determined to be 15%, since excessive amounts of CuS would operate as recombination centers and cover active sites. Additionally, the dual Z-scheme carriers movement mechanism was proposed using sacrificed agent experiments, and TOC analyzed the mineralization rate of RhB after degradation. In this study, CuS@ZnO/CdS photocatalyst degraded RhB nearly 99% in 80 min, which is superior to the earlier photocatalysts. Therefore, this article holds great significance in the practical application of metal chalcogenide-modified ZnO-based photocatalysts with superior visible light-induced degradation performance in environmental purification.