Z-scheme Charge Transfer Research Articles

Quantitative Spectroscopic Analysis of Surface-Reaching Photoexcited Holes in g-C3N4/TiO2 Z-Scheme Heterojunctions.

The Z-scheme heterojunction has been demonstrated to be effective in tuning the photocatalytic performance of photocatalysts. However, there is still a lack of quantitative and in-depth research on how the Z-scheme heterojunction affects the concentration of surface-reaching photoexcited charges. Here, by combining time-resolved spectroscopies and kinetic analysis, the concentration of surface-reaching photoholes (Ch+(surf)) within g-C3N4/TiO2 Z-scheme heterojunctions was quantitatively analyzed for the first time. Quantitative measurements reveal that Ch+(surf) of the prepared Z-scheme photocatalysts is highly dependent on the g-C3N4 content and the induced Z-scheme heterojunctions at the g-C3N4/TiO2 interface. Encouragingly, we found that a properly engineered Z-scheme heterojunction with close coupling of g-C3N4 and TiO2 can significantly increase the Ch+(surf), leading to nearly a 1.7-fold increase compared with pristine TiO2 samples. Furthermore, a distinct hole trap state-mediated Z-scheme charge transfer mechanism was uncovered in which the intrinsic interface defects at the g-C3N4/TiO2 junction act as hole traps, accelerating interface electron-hole recombination, thereby boosting spatial charge separation and ultimately enriching the Ch+(surf). This work provides insights into understanding and controlling electron pathways and Ch+(surf) in Z-scheme photocatalysis, with implications for the screening of different types of direct Z-scheme photocatalysts.

Photoelectrocatalytic degradation of organic contaminants by spray coated Z-scheme TiO2/Bi2WO6 heterostructure electrode under solar light

This study demonstrates that spray deposited layered TiO2/Bi2WO6 heterostructure photoelectrodes exhibit strong interfacial interactions, leading to significant enhancements in photoelectrochemical performance. Time-resolved photoluminescence (TRPL) spectra indicated a prolonged lifetime of photoinduced carriers. The red shift in the absorption edge of TiO2/Bi2WO6 improved the visible light harvesting capability of Bi2WO6. Nyquist plots showed effective charge separation, and the TiO2 layer at the bottom significantly influenced the flat band potential compared to pristine Bi2WO6, as evidenced by Mott-Schottky analysis. This configuration improved the separation of photogenerated charge carriers via a Z-scheme charge transfer mechanism. The TiO2/Bi2WO6 electrode demonstrated a higher efficiency of 94% for methylene blue degradation within 160 min, compared to pure Bi2WO6. Quenching experiments confirmed the Z-scheme charge transfer mechanism in the coupled TiO2/Bi2WO6 heterojunction during degradation reactions. This study highlights the benefits of semiconductor coupling with different band potentials, promoting large-scale applications of solar-driven TiO2/Bi2WO6 photoelectrodes for environmental remediation.

Synergistic photocatalytic activity of Bi2O3/g-C3N4/ZnO ternary heterojunction with dual Z-scheme charge transfer towards textile dye degradation

It is clear that a wide range of organic substances, including synthetic textile dyes, have the potential to negatively impact the environment. It is crucial to rationally develop highly effective photocatalysts for the degradation of such type of pollutants. In this regard, a heterostructured photocatalyst comes with enhanced charge separation and extended light absorption ability that improves photocatalytic performance. Therefore, In this study, a Bi2O3/g-C3N4/ZnO (BCNZ) ternary heterojunction photocatalyst was synthesized for the degradation of methylene blue (MB) textile dye.. Thermal polycondensation method was opted to synthesize g-C3N4, while ZnO and Bi2O3 photocatalysts were fabricated using co-precipitation method. Similarly, ternary heterojunction of BCNZ was constructed through co-precipitation method. The ternary heterojunction photocatalyst demonstrated better photodegradation ability due to dual Z-scheme charge transfer route. The dual Z-scheme heterojunction enabled the ternary heterojunction to exhibit enhanced light absorption capabilities with reduced recombination rates as well as enhanced charge separation and migration efficiency (confirmed via transient photocurrent response) that resulted in improved photocatalytic performance. The BCNZ dual Z-scheme photocatalyst displayed 92 % of degradation efficiency which was much higher than that of other (binary and pristine) photocatalysts. Scavenging tests and electron spin resonance spectroscopy revealed the significant role of the •O2−, and •OH radicals in the photodegradation of MB. Furthermore, the reusability test presented good stability and recyclability of the ternary photocatalyst with 80 % degradation efficiency after five catalytic cycles.

Activated charge transfer by interfacial S−O “bridge” at MnIn2S4/WO3 for eliminating kanamycin: Z-scheme mechanism, pathways and toxicity assessment

In the realm of heterojunction photocatalysis, the efficiency of carrier separation and overall photocatalytic reactions are significantly influenced by the accompanying resistance at the interface as well as the pathway of charge transfer. Herein, a covalently linked Z-scheme MnIn2S4/WO3 heterojunction with interfacial S−O bonds was synthesized through simple calcination and hydrothermal strategies. This tight heterostructure exerted the collaborative impact of interfacial covalent bonding in a Z-scheme model, and its significant role in facilitating the separation of charge carriers was investigated. 19 wt% WO3 combined MnIn2S4 (MIS/WO-19) delivered a remarkable degradation efficiency of 97.4 % for kanamycin, which was 8.8 times higher than that of pure MnIn2S4. The formation of S−O linkages between MnIn2S4 and WO3 was confirmed through experimental analyses and theoretical modeling. The proposed Z-scheme charge transfer pathway was examined by integrating quenching experiments, ESR tests, and DFT computations. This distinctive S−O bond, acting as a specialized “bridge”, in combination with the Z-scheme pathway, efficiently promoted the migration and segregation of photo-induced charges, leading to a notable enhancement in the degradation of kanamycin. Furthermore, the decomposition pathways of kanamycin were investigated through a collaborative approach involving mass spectrometry and DFT simulations, and a toxicity analysis of the intermediates was conducted by the computational toxicology.

Hydrogen Bonds and In situ Photoinduced Metallic Bi0/Ni0 Accelerating Z-Scheme Charge Transfer of BiOBr@NiFe-LDH for Highly Efficient Photocatalysis.

For heterojunction system, the lack of stable interfacial driving force and definite charge transfer channel makes the charge separation and transfer efficiency unsatisfactory. The photoreaction mechanism occurring at the interface also receives less attention. Herein, a 2D/2D Z-scheme junction BiOBr@NiFe-LDH with large-area contact featured by short interface hydrogen bonds and strong interfacial electric field (IEF) is synthesized, and in situ photoinduced metallic species assisting charge transfer mechanism is demonstrated. The hydrogen bonds between O atoms from BiOBr and H atoms from NiFe-LDH induce a significant interfacial charge redistribution, establishing a robust IEF. Notably, during photocatalytic reaction, Bi0 and Ni0 are in situ performed in heterojunction, which separately act as electron transport mediator and electron trap to further accelerate charge transfer efficiency up to 71.2 %. Theoretical calculations further demonstrate that the existence of Bi0 strengthens the IEF. Therefore, high-speed spatial charge separation is realized in Bi0/BiOBr@Ni0/NiFe-LDH, leading to a prominent photocatalytic activity with a tetracycline removal ratio of 88.3 % within 7 min under visible-light irradiation and the presence of persulfate, far exceeding majority of photocatalysts reported previously. This study provides valid insights for designing hydrogen bonding heterojunction systems, and advances mechanistic understanding on in situ photoreaction at interfaces.

Construction of a 2D/2D Vs-ZnIn2S4/Zn-TCPP heterojunction for effective charge transfer to enhance photocatalytic hydrogen evolution

The integration of inorganic and organic semiconductor components in composites has tremendous potential in photocatalysis, owing to the ultrafast photogenerated exciton dissociation and slow carrier recombination kinetics at their interfaces, which can result in enhanced photocatalytic performances. By exploiting the synergy among morphology modulation, sulfur vacancy (Vs) engineering, and close interface control, a novel inorganic–organic Vs-ZnIn2S4/ tetrakis (4-carboxyphenyl) zinc porphyrin (Zn-TCPP) composite for photocatalytic hydrogen evolution (PHE) was successfully synthesized via microwave-assisted solvothermal and self-assembly methods. The cocatalyst-free PHE rate of Vs-ZnIn2S4/Zn-TCPP (ZZT-20 %) reaches 8.997 mmol h−1 g−1 under visible light irradiation, which is 10.9, 2.2, and 67.1 times that of ZnIn2S4, Vs-ZnIn2S4, and Zn-TCPP, respectively. Moreover, the apparent quantum yield of ZZT-20 % under 420 nm monochromatic light (1.11 %) clearly exceeds that of Vs-ZnIn2S4. Testing experiments and DFT calculations revealed that the significantly enhanced PHE activity can be mainly attributed to the Z-scheme charge transfer mechanism, which greatly improves the visible light response range and redox potentials. Remarkably, Vs sites act as electron traps, inducing the vertical transport of electrons within the bulk phase and their accumulation at the surface Zn–S bonds. Simultaneously, van der Waals forces and weak hydrogen bonds between Vs-ZnIn2S4 and the Zn-TCPP interface cause the rapid migration of photogenerated electrons to Zn-TCPP. This work not only reveals new insights into the structure–property relationships of inorganic–organic Vs-ZnIn2S4 and Zn-TCPP composites, but also provides an appropriate strategy for cleaner water resourcelization and sustainable solar energy conversion.

Visible-light enhanced tetracycline degradation via SnO2/TiO2-Ni@rGO ternary heterostructures.

This study explores the synthesis, characterization, and photocatalytic performance of a SnO2/TiO2-Ni@rGO nanocomposite for tetracycline (TC) degradation under visible light irradiation. The nanocomposite was precisely designed to enhance structural stability, charge transfer efficiency, and catalytic activity. X-ray diffraction (XRD) analysis confirmed the structural integrity of the SnO2/TiO2-Ni@rGO composite, demonstrating excellent reusability and resistance to photo-corrosion after multiple cycles. Photocatalytic experiments revealed that the SnO2/TiO2-Ni@rGO nanocomposite significantly outperformed individual SnO2/TiO2-Ni and rGO catalysts, achieving a remarkable 94.6% degradation of TC within 60 min. The degradation process followed pseudo-first-order kinetics, with a rate constant (k) of 0.046 min-1. The Z-scheme charge transfer mechanism facilitated efficient separation and migration of photogenerated charge carriers, generating reactive oxygen species such as superoxide (•O2 -) and hydroxyl (•OH) radicals crucial for the oxidation of TC. Radical scavenger studies confirmed that superoxide and hydroxyl radicals were the primary active species. The SnO2/TiO2-Ni@rGO composite also exhibited excellent reusability, maintaining high catalytic performance over four consecutive cycles. These findings suggest that the SnO2/TiO2-Ni@rGO nanocomposite is a promising candidate for the efficient and sustainable photocatalytic degradation of persistent organic pollutants like TC, offering significant potential for environmental remediation applications.

Two-dimensional MoSTe/MSi2N4 (M = Mo, W) van der Waals heterojunctions for photocatalytic water-splitting: A first-principles study

Direct Z-scheme heterojunction is a promising candidate for photocatalysts because it effectively separates the photogenerated electrons-hole pairs with strong redox capacity. In this paper, the MoSTe-MSi2N4 (M = Mo, W) heterostructures are constructed, and their stability, electronic structures and photocatalytic performance are investigated. The results demonstrate that the absorption properties of heterojunctions are significantly better than that of monolayers in both visible and ultraviolet light regions. Expressly, heterojunctions have the direct Z-scheme charge transfer mechanism when S surface of MoSTe contacted with MSi2N4 (namely S-M). Further calculation find that the S-M heterojunctions can perform stable photocatalytic water splitting in both acidic and neutral environments, and have better hydrogen evolution reaction. These theoretical predictions suggest that the MoSTe-MSi2N4 heterostructures are high-performance photocatalysts for the preparation of hydrogen gas.

Fabrication of novel N-rich g-C3N5 decorated cubic spinel Co2SnO4 hybrids: Studies on morphology, degradation efficacy, pathway and mechanism

Managing interfacial charge transfer is a crucial and challenging problem in promoting the migration/separation of photogenerated carriers for heterojunction photocatalysts. The innovative dual Z-scheme heterojunction is crucial in effectively removing organic pollutants by enhancing the separation of charge carriers. A novel Co2SnO4/g-C3N5 (CoSn/CN) nanocomposite heterojunction is synthesized using a simple hydrothermal approach. The resulting nanocomposite is then studied in terms of its crystal phases, optical characteristics, surface morphologies, and compositions. The charge separation efficiency is significantly enhanced, resulting in a high-efficiency photocatalytic degradation performance. The CoSn/CN photocatalyst exhibits a degradation efficiency of 99.11 % and 98.08 % for Congo red (CR) and Rose Bengal (RB) respectively, within 75 minutes and 50 minutes under visible light conditions. In addition, scavenging tests demonstrated the generation of active radical species, specifically •OH, h+, and •O2−. The hypothesized CR and RB degradation process and potential pathways were derived from the proper experimental study. The primary objective of this project is to create a novel photocatalytic material that can effectively degrade dyes. Additionally, the study aims to construct a larger-scale photocatalytic system, determine the cost of the wastewater treatment unit, and analyze the life cycle of the entire process. In addition, the Co2SnO4/g-C3N5 heterojunction also demonstrates the expected stability as no substantial drop was observed after 5 cycles. The exceptional degrading performance and stability of the system can be attributed to the enhanced separation of photo-induced charge carriers and the strong contact at the interface, achieved through the formation of a Z-Scheme charge transfer.

Attuned band structure in triple S-scheme heterojunctions for naproxen degradation under visible light

The limited charge carrier separation and transportation in single semiconductor photocatalysts has lobbied research and development in rational design and fabrication of heterojunction photocatalysts which has become a hot topic in the last decade. In-depth investigation of a four-component semiconductors interfacial charge transfer analysis considering the contribution of all components was done for the first time to deduce triple S-scheme heterojunction. This work investigated four-component semiconductors (Cu3(PO4)2, BaWO4, C-MgO and LDH) heterojunction photocatalyst formation by the solvothermal method for visible light degradation of NPX. The degradation rate of CBLM-B (0.0429 min−1) with high BaWO4 content was two times the degradation rate of CBLM-A (0.0203 min−1) with high LDH/C-MgO content. XPS, electrochemistry, and band structure analysis were used to propose a triple S-scheme heterojunction with high electron mobility and charge separation that enhanced the formation of OH• >•O2− > h+ species as supported by radical trapping experiments due to presence of two oxidative and two reductive sites for stable generation of ROSs. Internal electric field (IEF) and band bending modulated an S-S interfacial strategy at the three junctions. Cu leaching affected the catalyst stability, and NPX degradation pathways were investigated with QTOF-HPLC-MS. This work demonstrated band structure adjustment for design of highly efficient triple S-Scheme heterojunctions application in environmental pollution remediation as a new development to advance scientific knowledge on four-component heterojunctions which may also be described using the Z-scheme charge transfer model.

Facile synthesis of a novel CeCO3OH@(H/C–CdS) catalyst with synergistic effect of heterophase junction and heterojunction for enhanced visible-light photocatalytic degradation efficiency at room temperature

A new CeCO3OH@(hexagonal/cubic phases–CdS) (CeCO3OH@(H/C–CdS)) composite catalyst was facilely synthesized by a simple microinjection titration–stirring method, in which CdS nanoparticles were dispersed on the surface of CeCO3OH nanolines. The optimal conditions for the preparation of composite catalysts with high photocatalytic performance were determined by single-factor experiments and response surface experiments. Under these conditions, the degradation rate of 30 mL 2.000 g/L rhodamine B (Rh B) by CeCO3OH@(H/C-CdS) in a photocatalytic reaction for 1 h at 25 °C was up to 86.81 % and its degradation rate in a photocatalytic reaction for 150 min was up to 99.62 %. The degradation rate could be maintained above 80 % even after six times recycling. Especially, the photocatalytic degradation efficiency of 2.000 g/L Rh B on the composite catalyst under sunlight and at room temperature for 30 min reached 97.66 %. Meanwhile, the large size of CeCO3OH considerably alleviated the agglomeration of CdS, providing more adsorption and active sites for visible light-mediated degradation of Rh B. Importantly, the Z-scheme charge transfer realized by CdS and CeCO3OH enhanced the efficient separation of photogenerated electrons and holes, and successfully inhibited the recombination of photogenerated electrons with holes. At the same time, owing to the low energy band difference between the two phases of CdS, charge was transferred between the hexagonal and cubic phases, leaving more effective photogenerated charge to participate in the degradation of Rh B. The synergism of the heterophase junction and heterojunction and the presence of oxygen and sulfur vacancies considerably enhanced the degradation performance of the catalyst. Thus, this study provides a new strategy for the modification and enhanced visible-light catalysis performance of CdS-based catalysts.

Photoreduction of carbon dioxide into methane and ethylene using TiO2 inverse opal-derived PCN-222(M)

Solar-driven photocatalytic CO2 reduction has significant potential to address the energy crisis and mitigate greenhouse gas emissions by producing valuable organic compounds. Narrow bandgap materials enhance photon absorption within the visible light spectrum, thereby improving exciton generation. Both the inverse opal (IOT) and the porphyrin-based MOF (PCN-222) exhibit biomimetic design concepts. The IOT has a highly ordered porous structure that increases the light-absorbing surface area, facilitating efficient light harvesting. Conversely, the PCN-222 structure, which is modelled on biological porphyrin molecules, has a highly ordered pore structure and abundant active centers. Under hydrothermal conditions, PCN-222 self-assembles on the IOT surface to form a P(Cu, Fe, Zn)/IOT heterostructure. The tight interface of this heterostructure promotes rapid electron-hole separation and transport. In addition, the slow-light effect is exploited to increase the light absorption efficiency, thus improving the overall photocatalytic reaction efficiency and stability. In this study, the morphology, structure and photoelectric properties of P(Cu, Fe, Zn)/IOT heterostructures are investigated, revealing enhanced photocatalytic efficiency. The P(Fe)/IOT composite demonstrated outstanding CO2 conversion rates under simulated sunlight, yielding carbon monoxide (62 %), methane (0.11 %), and ethylene (0.09 %). The Z-scheme charge transfer mechanism significantly enhances photocatalytic performance by improving the efficiency of carrier separation and transfer, thereby increasing the overall photocatalytic reaction efficiency. This advance offers significant benefits for environmental and renewable energy remediation. The study provides key insights and recommendations for enhancing the efficiency of Z-scheme photocatalytic systems in future research and development.

Synergistic strategy of Z-scheme heterojunction and defect engineering to construct ZnS/CoSx nanospheres for excellent photocatalytic H2 evolution performance

The design of Z-scheme heterojunction to realize the efficient separation of charge carriers still remain challenging. Herein, the defect-assisted Z-scheme heterojunction strategy has been proposed. The binary ZnS/CoSx nanospheres were successfully prepared via a well-designed hydrothermal approach. The resultant ZnS/CoSx nanospheres with CoSx content of 5 wt% exhibit the optimal hydrogen production rate of 2546.6 μmol g−1h−1, which is 2.6 times higher than that of pure ZnS and superior to the most reported ZnS-based composites. The enhancement of S-vacancy concentration can greatly strengthen photocatalytic hydrogen evolution property, which can be originated from the boosted direct Z-scheme charge-transfer process in ZnS/CoSx heterostructures. The synergistic effect of direct Z-scheme heterostructures and defects engineering notably enhances the photocatalytic activity of ZnS/CoSx nanospheres, which could provide a deep insight for the design and synthesis of new types of photocatalysts.

SiC/PtSe2 van der Waals heterostructure: A high-efficiency direct Z-scheme photocatalyst for overall water splitting predicted from first-principles study

The discovery of effective photocatalytic substances is crucial in reducing energy shortages and ecological contamination. This research involves creating SiC/PtSe2 van der Waals heterostructure with both SiC and PtSe2 monolayers, employing first-principles calculations for comprehensive theoretical analysis of their structural stability, electronic characteristics, optical features, Bader charge, and solar-to-hydrogen (STH) efficiency. Findings indicate that the SiC/PtSe2 heterostructure is a semiconductor with an indirect bandgap of 1.52 eV and a direct Z-scheme charge transfer path, facilitating more efficient segregation of photogenerated electron-hole pairs. The Bader charge indicates that the SiC layer accumulates positive charges and the PtSe2 layer accumulates negative charges, constituting a built-in electric field pointing from the SiC side to the PtSe2 side at the interface region, which can impede the complexation of the photogenerated electron-hole pairs. Furthermore, the SiC/PtSe2 heterostructure exhibits excellent optical absorption properties across both the ultraviolet and visible spectra, coupled with an exceptionally high STH efficiency of 34.7 %, significantly enhancing solar energy utilization. Ultimately, the Gibbs free energy calculations reveal the significant catalytic efficiency of the SiC/PtSe2 heterostructure for redox reactions. Based on these results, the SiC/PtSe2 heterostructure is a direct Z-scheme photocatalyst for overall water splitting.

Heterojunction photocatalyst MnO2-CsSnI3 for highly efficient formaldehyde oxidation at room temperature

The effective removal of the low-concentration formaldehyde (HCHO) in the indoor environment is a critical issue affecting the quality of people’s daily lives. In this study, heterojunction catalysts composed of manganese dioxide (MnO2) and cesium tin iodine (CsSnI3) nanocrystals were first synthesized and successfully used for photocatalytic HCHO degradation. After the full band light irradiation (150 mW/cm2) for 3 h, the concentration of HCHO decreased from 7 ppm to a minimum of 0.03 ppm at room temperature (25 °C, 25 % RH, degradation efficiency reaches up to 99.6 %). Subsequent analysis using electron paramagnetic resonance (EPR) and transmission electron microscopy (TEM) revealed that the MnO2-CsSnI3 heterojunction photocatalyst not only offers a Z-scheme charge-transfer pathway but also promotes the generation of a large number of •O2− and •OH. Compared to the single-phase material, the concentration of •O2− and •OH has increased by 1.5 times. This MnO2-based Z-scheme heterojunction photocatalyst provides a novel strategy for the degradation of low-concentration HCHO in practical indoor environments.

Enhanced photocatalytic degradation of brilliant green using g-C3N5/WO3 nanocomposite: A Z-scheme charge transfer approach under visible light irradiation

The industrial use of dyes is harming natural ecosystems. Photocatalysis is a potentially useful method for addressing these kinds of environmental contaminants. The present study addresses the synthesis of a novel g-C3N5/WO3 Z-scheme heterojunction via the ultra-sonication method and the calcination method with the use of a triazole. The toxic dye, brilliant green (BG) was degraded by utilizing the prepared photocatalyst. The elemental composition, surface morphology and structureof the prepared g-C3N5/WO3nanocomposite were analysed using various techniques including XPS, PL, SEM-EDAX, HRTEM, and XRD. The average diameter of the g-C3N5/WO3 nanocomposite was found to be 44 nm using TEM. The optical properties were analysed using UV-DRS. The as-synthesized g-C3N5/WO3nanocomposite had a direct band gap of 2.27 eV, as determined fromTauc’s plot and demonstrated exceptional photocatalytic degradation efficacy for the elimination of the BG dye via the Advanced Oxidation Process (AOP). A degradation efficacy of 99.4 % within a short interval of time of 60 min was achieved by the prepared photocatalyst under various optimum situations. The rate constant of the photocatalytic reaction was calculated to be 0.05994 min−1 following a pseudo first order kinetics. Additionally, with an efficiency of90.17 %the photocatalyst can be recycled upto the fourth cycle. The current work accomplishes the goal of creating an innovative and effective photocatalyst that is responsive towards visible light.

In Situ Synthesis of Exfoliated Ni(OH)2 Nanosheets and AgNPs-Embedded Functionalized Polyindole-Based Trinary Hybrid Microspheres: A Z-Scheme Photocatalyst for the Sunlight-Driven Degradation of Organic Pollutants with Enhanced Antibacterial Efficacy.

Advancing a facile one-pot synthetic approach for the fabrication of a hybrid heterojunction photocatalyst remains a significant challenge in research pursuits. Herein, a microsphere-like trinary hybrid nanocomposite has been synthesized (NH/PIn/MAA/Ag). It comprises exfoliated single- and a few-layered Ni(OH)2 (NH nanosheets), mercaptoacetate-functionalized polyindole (PIn/MAA), and Ag nanoparticles (AgNPs) through an in situ approach. The formation mechanism is based on the exfoliation of stacked Ni(OH)2 multilayers [i.e., Ni(OH)2 microflowers] and stabilization of NH nanosheets through host-guest formation of PIn/MAA, followed by the adsorption-reduction of Ag+ ions in a one-pot reaction at low temperature. Surface morphological analyses of hybrid nanocomposite microspheres have exhibited that highly dense Ni(OH)2 microflowers have been transformed into low-density layered forms (NH nanosheets) within the polymeric platform (PIn/MAA) with deposited AgNPs. An interfacial heterojunction has been developed between the components in the depletion region, leading to an improvement in photocatalytic efficiency through a synergistic effect over the components for charge separation and transfer through the heterojunction interface via solid-state mediator Ag-based Z-scheme charge transfer dynamics. The superior photocatalytic degradation of tetracycline (98.2%) by trinary hybrid microspheres can be attributed to the deteriorated recombination rate of electron-hole pairs with reduced charge transfer resistance of the heterojunction in the photocatalyst, as obvious from photoluminescence, electrochemical impedance spectroscopy, chronoamperometry, and time-resolved photoluminescence (TRPL) analyses. Moreover, the antibacterial properties of microspheres against Bacillus pumilus (Gram-positive) and Escherichia coli (Gram-negative) bacteria have validated their potential as promising materials for the overall purification of aquatic systems.

Host-Guest Interaction Mediated Perovskite@Metal-Organic Framework Z-Scheme Heterojunction Enabled Paper-Based Photoelectrochemical Sensing.

Exploring the high-performance photoelectronic properties of perovskite quantum dots (QDs) is desirable for paper-based photoelectrochemical (PEC) sensing;however, challenges remain in improving their stability and fundamental performance. Herein, a novel Z-scheme heterostructure with host-guest interaction by the confinement of CH3NH3PbBr3 QDs within Cu3(BTC)2 metal-organic framework (MOF) crystal (MAPbBr3@Cu3(BTC)2) is successfully constructed on the paper-based PEC device for ultrasensitive detection of Ochratoxin A (OTA), with the assistance of the exciton-plasmon interaction (EPI) effect. The host-guest interaction is estabilished by encapsulating MAPbBr3 QDs as guests within Cu3(BTC)2 MOF as a host, which prevents MAPbBr3 QDs from being damaged in the polar system, offering access to long-term stability with high-performance PEC properties. Benefiting from the precise alignment of energy levels, the photogenerated charge carriers can migrate according to the Z-scheme charge-transfer pathway under the driving force of the internal electric field, achieving a high photoelectric conversion efficiency. Upon OTA recognition, the EPI effect is activated to modulate the exciton response in MAPbBr3 QDs by accelerating radiative decay, finally achieving sensitive OTA sensing with a detection limit of 0.017 pg mL-1. We believe this work renders new insight into designing host-guest Z-scheme heterojunctions in constructing the paper-based PEC sensing platforms for environmental monitoring.

Visible-Light Photocatalytic Degradation Efficiency of Tetracycline and Rhodamine B Using a Double Z-Scheme Heterojunction Catalyst of UiO-66-NH2/BiOCl/Bi2S3.

BiOCl is a promising photocatalyst, but due to its weak visible light absorption capacity and low photogenerated electron-hole pair separation rate, its practical application is limited to a certain extent. In this study, a novel double Z-scheme heterojunction UiO-66-NH2/BiOCl/Bi2S3 catalyst was constructed to broaden the visible light response range and promote high photogenerated hole-electron separation of BiOCl. Its photocatalytic performance is evaluated by dissociating tetracycline (TC) and rhodamine B (RhB) in visible light. The optimal proportion of UiO-66-NH2/BiOCl/Bi2S3 hybrids exhibits the best degradation efficiency of visible light illumination (∼93% in 120 min for TC and ∼98% in 60 min for RhB). The synergistic effect of a large visible light response range and the Z-scheme charge transfer mechanism ensure the excellent visible photocatalytic activity of UiO-66-NH2/BiOCl/Bi2S3. It is proven that h+ and •O2- are the main active substances in the photocatalysis process by active substance capture experiments and electron spin resonance tests. The intermediates and degradation processes are analyzed by high-performance liquid chromatography-mass spectrometry. This study proves that the new UiO-66-NH2/BiOCl/Bi2S3 photocatalyst has great application potential in the field of water pollution degradation and will provide a new idea for the optimization of BiOCl.

Simultaneous dopants and defects synergistically modulate the band structure of CN in Z-scheme heterojunctional photocatalysts for simultaneous HER and OER production

Enhancing solar-driven oxygen evolution reactions (OER) and hydrogen evolution reactions (HER) is critical for advancing renewable energy solutions and mitigating global CO2 emissions. In this study, we employed a blend of experimental and theoretical approaches to improve the properties of graphitic carbon nitride (CN). This improvement entailed the introduction of isolated boron dopants and nitrogen deficiency into CN, achieved via a straightforward calcination process with sodium borohydride, followed by the integration of ultrathin iron phthalocyanine (FePc) connected through phosphate groups. The synthesized nanocomposite, FePc/P–BCNN, exhibited exceptional photocatalytic efficacy in OER and HER, reaching production rates of 915.4 μmol h−1 and 99.5 μmol h−1, marking a substantial enhancement-nearly 8- & 9-fold over traditional CN materials under visible light. This remarkable efficiency stems from a deliberate modification of the conduction and valence bands through the incorporation of B-dopants and N-defects, thereby fine-tuning the band structure for improved OER and HER performance. Furthermore, the potential of ultrathin metal phthalocyanine structures, offering multiple single-atom active sites, and showcased a sustainable approach for photocatalytic OER and HER. The rapid charge separation, propelled by a Z-scheme charge transfer mechanism, facilitated through a dimensionally matched strategy contributes novel insights into the field of sustainable energy conversion technologies.