Direct Transfer Mechanism Research Articles

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.

Investigation of the synergistic photocatalytic activity of a ternary ZrTiO4/TiO2/Mn3O4 (ZTM) nanocomposite in a typical water treatment process

Because of the exploration of the increase in the aqueous environment caused by various organic pollutants, an urgent need is sensed to develop novel photocatalysts with high efficiency. Here, ZrTiO4/TiO2/Mn3O4 (ZTM) was in-situ synthesized and relatively well-characterized by XRD, FTIR, UV–Vis DRS, EIS, TG/DTG, TPD, SEM, TEM, and BET characterization techniques. Diffraction data showed the crystallite sizes of about 22 and 13 nm obtained by the Scherrer and Williamson-Hall formulas, respectively, with a d-spacing of about 0.21 nm. Then, the composite catalyst was applied in the photodegradation of Metoclopramide (MCP) and showed a boosted photocatalytic activity concerning ZrTiO4, TiO2, and Mn3O4 alone. The effective surface area of 105, 54, and 93 m2/g were obtained in BET analysis of ZTM, Mn3O4, and TiO2. ZTM, Mn3O4, TiO2, and ZrTiO4 band gap energies were obtained via the DRS spectra as 2.22, 1.88, 3.05, and 3.31 eV The scavenging agent's study confirmed that hydroxyl radical and photoinduced electrons have higher roles in the MCP photodegradation process, accordingly confirmed by a sequential direct Z-scheme charge transfer mechanism in the composite.

BaTi0.85Zr0.15O3/MOF-5 nanocomposite: Synthesis, characterization and photocatalytic activity toward tetracycline

It has been proposed that oriented anchoring strategies can be used to organize BaTi0.85Zr0.15O3 (BTZ) quantum dots (QD) with MOF-5 to provide highly efficient catalytic degradation of tetracycline (TC). This study presents the preparation of [Zn4O (BDC)3] (BDC = benzene-1,4dicarboxylate) metal–organic framework-5 (MOF-5)/BTZ nanocomposites by a facile one-pot solvent-thermal precipitation method. The as-synthesized samples were identified by XRD, TG-DTG, UV–VIS DRS, FESEM, FTIR, BET, TEM, PL, and EDX characterization techniques. The photocatalytic ability of nanocomposite BTZ (30 %wt)/MOF-5 was particularly impressive among the binary photocatalysts. In a 10 ppm solution of TC, BTZ (30 wt%)/MOF-5 demonstrated superior photodegradation activity, with 95 % degradation efficiency of TC determined by HPLC. The best response was achieved at pH 11 with catalyst dosages of 0.2 g/L, irradiation time of 150 min, and CTC of 10 ppm. An internal electric field was suggested to mediate the direct Z-scheme charge transfer mechanism between BTZ and MOF-5. The improvement was achieved by fabricating BTZ and MOF-5 in an indirect Z-scheme heterojunction system. Photogenerated electron-hole separation can be accelerated by BTZ/MOF-5 with improved redox capabilities. Overall, taking advantage of an enhanced redox capacity under ultraviolet (UV) light irradiation, this study demonstrates how to promote efficient antibiotic degradation using MOF-based nanocomposites. Moreover, photodegradation kinetics were studied using the Hinshelwood formula, giving 0.0113 min−1 (slope) and 61.32 min as t1/2. In the COD experiment, mineralized TC molecules had y = -0.0144 + 0.0444x, r2 = 0.9942, and k = 0.0144 min−1 (t1/2 = 48.12 min).

A direct Z-scheme 0D α-Fe2O3/TiO2 heterojunction for enhanced photo-Fenton activity with low H2O2 consumption

The insufficient F(III)/Fe(II) cycling rate resulted from high combination of photogenerated carriers severely hinders the photo-Fenton activity. In this work, 0 dimensional α-Fe2O3 nanoclusters decorated TiO2 heterojunction (FT-x) was prepared via in-situ phase transformation strategy. FT-200 exhibited the optimal photo-Fenton activity for 2,4-dichlorophenol degradation with the kinetic rate constant reaching 1.0806 min−1 under low H2O2 dosage (1 mmol/L), which was 126.1 and 202.8 times higher than that of TiO2 and α-Fe2O3. Radical quenching experiments and electron spin resonance spectra proved that ·OH was the leading reactive specie. The enhanced photo-Fenton activity was attributed to the accelerated F(III)/Fe(II) cycling rate induced by the direct Z-Scheme charge transfer mechanism. Benefiting from the abundant ·OH production, the dechlorinate ratios and mineralization ratios of multiple chlorophenol pollutants (2,4-dichlorophenol, 4-chlorophenol, 2,4,6-trichlorophenol) all exceeded 98%. The biotoxicity of chlorophenol wastewater was greatly reduced after the treatment by Light/H2O2/FT-200 system. Overall, this work constructed a low-cost and highly efficient photo-Fenton system for refractory organic wastewater treatment.

Flexible humidity sensor based on PEDOT:PSS/Mxene nanocomposite

Flexible humidity sensor is essential in emerging applications including health care monitoring, soft robots, human-machine interfaces and noncontact measurements for important indicators. This study presents the development of a highly efficient flexible humidity sensor utilizing a nanocomposite of poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) and Mxene as the sensing material coated onto a flexible polyethylene terephthalate substrate. The nanocomposite was thoroughly characterized using UV/Vis spectroscopy, transmission electron microscopy, scanning electron microscope and Fourier-transmission infrared spectroscopy to assess its quality, morphology, and chemical functional groups. The results show a good linkage of p-type PEDOT:PSS and p-type Mxene sensing nanocomposite. The PEDOT:PSS/Mxene humidity sensor exhibits high sensitivity of 3.27%ΔR/%ΔRH at room temperature. The PEDOT:PSS/MXene nanocomposite offers an enhanced humidity performance by synergies of direct charge transfer and swelling mechanism as well as hydrogen bonding and electrostatic interaction.

Direct Z-scheme In2S3@BiYWO6 heterojunction photocatalysts for highly efficient environmental remediation

Novel In2S3@BiYWO6 heterojunction photocatalysts were designed and synthesized by a simple two-step hydrothermal method, which exhibit extremely excellent photocatalytic activity for degrading the residual antibiotics in wastewater. Especially, In2S3@BiYWO6 composite with mass ratio of 10:1 shows the highest photo-degradation efficiency towards Tetracycline Hydrochloride, which is about 2.46 and 7.55 times than that of pristine In2S3 and BiYWO6, respectively. A direct Z-scheme charge transfer mechanism was demonstrated in these heterojunctions through the XPS analysis, radical species trapping experiments and fluorescence detection. Within the framework of this mechanism, the critical built-in electric field (Ei) formed at the contact interface between In2S3 and BiYWO6 spatially separates reduction or oxidation sites and thus preserves the photogenerated carriers with stronger redox ability on reaction sites, which ultimately enhances the photocatalytic activity of the heterojunction catalysts. It is commendable that such Z-scheme heterostructures between In2S3 and BiYWO6 exist in a wide span of component ratios (from 5:1 to 30:1), which is beneficial for the environmental remediation applications. It is believed that this work provides new ideas for design and synthesis of novel Z-scheme heterojunction photocatalysts.

Uranyl Polyoxotungstate Cluster for Visible-Light-Driven Heterogeneous C-H Selective Fluorination.

The selective fluorination of C-H bonds at room temperature using heterogeneous visible-light catalysts is both interesting and challenging. Herein, we present the heterogeneous sandwich-type structure uranyl-polyoxotungstate cluster Na17{Na@[(SbW9O33)2(UO2)6(PO3OH)6]}·46H2O (denoted as U6P6) to regulate the selective fluorination of the C-H bond under visible light and room temperature. This is the first report in which uranyl participates in the fluorination reaction in the form of an insoluble substance. U6P6 is capable of the effective selective fluorination of cycloalkanes and the recyclability of the photocatalyst due to the synergistic effect of multiple uranyl (UO2)2+ and the insolubility of organic reagents of polyoxotungstate. In situ electron paramagnetic resonance spectroscopy captured the generation of cycloalkane radicals during the photoreaction, confirming the mechanism of direct hydrogen atom transfer.

Multiple RNA- and DNA-binding proteins exhibit direct transfer of polynucleotides with implications for target-site search

We previously demonstrated that the polycomb repressive complex 2 chromatin-modifying enzyme can directly transfer between RNA and DNA without a free-enzyme intermediate state. Simulations suggested that such a direct transfer mechanism may be generally necessary for RNA to recruit proteins to chromatin, but the prevalence of direct transfer capability is unknown. Herein, we used fluorescence polarization assays and observed direct transfer for several well-characterized nucleic acid-binding proteins: three-prime repair exonuclease 1, heterogeneous nuclear ribonucleoprotein U, Fem-3-binding factor 2, and MS2 bacteriophage coat protein. For TREX1, the direct transfer mechanism was additionally observed in single-molecule assays, and the data suggest that direct transfer occurs through an unstable ternary intermediate with partially associated polynucleotides. Generally, direct transfer could allow many DNA- and RNA-binding proteins to conduct a one-dimensional search for their target sites. Furthermore, proteins that bind both RNA and DNA might be capable of readily translocating between those ligands.

Mechanisms of Sulfoxidation and Epoxidation Mediated by Iron(III)-Iodosylbenzene Adduct: Electron-Transfer vs. Oxygen-Transfer Mechanism.

The mechanisms of sulfoxidation and epoxidation mediated by previously synthesized and characterized iron(III)-iodosylbenzene adduct, FeIII(OIPh) were investigated using para-substituted thioanisole and styrene derivatives as model substrates. Based on detailed kinetic reaction experiments, including the linear free-energy relationships between the relative reaction rates (logkrel) and the σp (4R-PhSMe) with ρ = -0.65 (catalytic) and ρ = -1.13 (stoichiometric), we obtained strong evidence that the stoichiometric and catalytic oxidation of thioanisoles mediated by FeIII(OIPh) species involves direct oxygen transfer. The small negative slope -2.18 from log kobs versus Eox for 4R-PhSMe gives further clear evidence for the direct oxygen atom transfer mechanism. On the contrary, with the linear free-energy relationships between the relative reaction rates (logkrel) and total substituent effect (TE, 4R-PhCHCH2) parameters with slope = 0.33 (catalytic) and 2.02 (stoichiometric), the stoichiometric and catalytic epoxidation of styrenes takes place through a nonconcerted electron transfer (ET) mechanism, including the formation of the radicaloid benzylic radical intermediate in the rate-determining step. On the basis of mechanistic studies, we came to the conclusion that the title iron(III)-iodosylbenzene complex is able to oxygenate sulfides and alkenes before it is transformed into the oxo-iron form by cleavage of the O-I bond.

PRC2 direct transfer from G-quadruplex RNA to dsDNA has implications for RNA-binding chromatin modifiers

The chromatin-modifying enzyme, Polycomb Repressive Complex 2 (PRC2), deposits the H3K27me3 epigenetic mark to negatively regulate expression at numerous target genes, and this activity has been implicated in embryonic development, cell differentiation, and various cancers. A biological role for RNA binding in regulating PRC2 histone methyltransferase activity is generally accepted, but the nature and mechanism of this relationship remains an area of active investigation. Notably, many invitro studies demonstrate that RNA inhibits PRC2 activity on nucleosomes through mutually antagonistic binding, while some invivo studies indicate that PRC2's RNA-binding activity is critical for facilitating its biological function(s). Here we use biochemical, biophysical, and computational approaches to interrogate PRC2's RNA and DNA-binding kinetics. Our findings demonstrate that PRC2-polynucleotide dissociation rates are dependent on the concentration of free ligand, indicating the potential for direct transfer between nucleic acid ligands without a free-enzyme intermediate. Direct transfer explains the variation in previously reported dissociation kinetics, allows reconciliation of prior invitro and invivo studies, and expands the potential mechanisms of RNA-mediated PRC2 regulation. Moreover, simulations indicate that such a direct transfer mechanism could be obligatory for RNA to recruit proteins to chromatin.

Analysis of two-particle transfer reaction in the 18O+40Ca and 20Ne+116Cd collisions

Two-neutron and two-proton transfer reactions have been analyzed in the present work. These kind of transfer reactions is an excellent tool to get insights into the short-range correlations on nucleons in a nuclear state. The direct and sequential two-particle transfer mechanisms, for which the valence particles can be transferred, were compared one with other to probe the populated nuclear states. Large-scale shell model calculations were performed to obtained the spectroscopic amplitudes for one and two valence particles.

An Unprecedented Strategy to Fabricate Inside/Surface Homojunction in Bismuth Oxychloride for Efficient Photocatalysis

The design of an efficient homojunction in bismuth oxychloride via simple means is still challenging. Herein, an inside/surface homojunction of bismuth oxychloride via fabricating surface-layer oxygen vacancies from a sulfur dopant and surface-layer hydroxyl from an alkali modification (BOCSO) in a one-pot hydrothermal process is successfully prepared. BOCSO exhibits enlarged specific surface area, improved adsorption of substrate, and enhanced photogenerated charge separation and transfer efficiencies. Extensive characterizations and density functional theory (DFT) calculations demonstrate BOCSO can form a defect level via surface oxygen vacancies and S doping to narrow the energy gap and capture the photogenerated electrons and holes. Meanwhile, both oxygen vacancies and hydroxyls on the BOCSO surface can also form an inside/surface homojunction containing an interfacial electric field (IEF) to induce a direct Z-scheme charge transfer mechanism. Taking advantage of the above, the photocatalytic degradation activity is remarkably elevated compared to that of pristine BiOCl (BOC). This work provides a new strategy for the fabrication of an inside/surface homojunction in bismuth oxychloride via novel surface modification engineering.

Photo-Fenton assisted AgCl and P-doped g-C3N4 Z-scheme photocatalyst coupled with Fe3O4/H2O2 system for 2, 4-dimethylphenol degradation

In this study graphitic carbon nitride (g-C3N4 or GCN) and phosphorus doped graphitic carbon nitride (p-g-C3N4 or PCN) were prepared using facile thermal polycondensation method. Phosphorus doping was employed to preserve the non-metallic nature of GCN. The AgCl/PCN/Fe3O4 heterojunction was synthesized using a simple in-situ route. The photocatalytic performance of the GCN, PCN, Fe3O4 and AgCl/PCN/Fe3O4 was tested towards 2, 4-dimethylphenol (DMP) pollutant. The work explored improvement in physiochemical properties and reduction of band gap of GCN after P doping (through Tauc's plot method). Coupling with AgCl (silver halide) also enhanced photoinduced charge carriers' separation and migration ability due to apt band alignment among both AgCl and PCN photocatalysts which resulted in formation of direct Z-scheme charge transfer mechanism. Similarly, the incorporation of ferrimagnetic material i.e. Fe3O4 enhanced the generation of hydroxyl (•OH) radicals via photo-Fenton process and facilitated photocatalysts easy separation from the aqueous medium. Through PL and EIS analysis the enhanced charge separation and migration ability in AgCl/PCN/Fe3O4 nanocomposite was validated. The attained DMP degradation efficiency of photo-Fenton assisted AgCl/PCN/Fe3O4/H2O2 Z-scheme nanocomposite was much higher i.e. 99% compared to other photocatalysts within 60 min of visible light irradiation following pseudo-first-order kinetics. Electron paramagnetic resonance (EPR) and scavenging tests confirmed the substantial role of •OH and •O2− radicals in the photo-Fenton reaction. Furthermore, liquid chromatography-mass spectrometry (LC-MS) analysis detected the generated oxidative products and mineralization pathways associated with DMP degradation. The proposed direct Z-scheme charge transfer route presented efficient charge separation and migration ability in AgCl/PCN/Fe3O4 nanocomposite. Recycle ability of the fabricated AgCl/PCN/Fe3O4 photocatalyst was tested up to 5 cycles with 90% removal efficacy, confirming the excellent reusability and stability of AgCl/PCN/Fe3O4 photocatalyst.

Direct Z-scheme heterojunction Bi/Bi2S3/α-MoO3 photoelectrocatalytic degradation of tetracycline under visible light

A hot research topic in visible-light-driven photoelectrocatalytic (PEC) oxidation technology is the development of superior photoanode materials. The design of the photoanode system with a direct Z-scheme charge transfer mechanism is crucial to achieving effective charge separation for sustainable photoelectrocatalysis. Here, a novel Bi/Bi2S3/α-MoO3 heterostructure was successfully assembled by a simple and feasible strategy. The direct Z-scheme heterogeneous formed between Bi2S3 and α-MoO3 has the advantages of low resistance, high optical response current and the surface plasmon resonance (SPR) effect of Bi nanoparticles (Bi NPs). Thus, the efficiency of photogenerated carrier separation and transfer is further enhanced, and the catalytic activity is significantly improved. It is impressive that the unique photoanode has achieved a maximum removal efficiency of 85.8% of tetracycline (TC) pollutants under visible light irradiation within 60 min and has excellent stability, which is expected to degrade antibiotics efficiently and environmentally in harsh environments. These characteristics give Bi/Bi2S3/α-MoO3 promising candidates for practical applications in antibiotic degradation.

Construction of novel g-C3N4 coupled efficient Bi2O3 nanoparticles for improved Z-scheme photocatalytic removal of environmental wastewater contaminant: Insight mechanism

Recently, the major environmental pollution produced by the release of wastewater in liquid type is one of the most extensive forms of foremost pollution in water ecosystems. In this article, the Bi2O3/g-C3N4 nanocomposite with a direct Z-scheme was effectively obtained by a facile hydrothermal system. The crystal structures, surface morphology, chemical composition, and the optical belongings of the as-obtained composite catalysts were examined by Power XRD, FT-IR spectra, High-resolution XPS spectra, FE-SEM images with EDX spectra, High-resolution TEM images, UV–Vis DRS, and PL spectra respectively. Furthermore, the photocatalytic performance was assessed by the degradation of aqueous Rhodamine B (Rh B) dye under visible-light exposure. The Bi2O3/g-C3N4 composite photocatalysts (PCs) showed the maximum photo-degradation efficiency through a rate constant value of 0.0149 min−1, which is 4.9 and 5.3 folds superior to Bi2O3, and GCN, respectively. The better GBO2 nanocomposite PCs showed a superior photocatalytic degradation performance (>82%) of aqueous Rh B dye after five successive recycles. Moreover, based on these outcomes of the radical scavenging test, a direct and effective Z-scheme photocatalytic charger transfer mechanism was also projected. Finally, the reusability of the as-obtained Bi2O3/g-C3N4 nanocomposite has better stability and reusability, which was a favourable applicant for wastewater handling.

Direct Z-Scheme g-C3N5/Cu3TiO4 Heterojunction Enhanced Photocatalytic Performance of Chromene-3-Carbonitriles Synthesis under Visible Light Irradiation

In order to make the synthesis of pharmaceutically active carbonitriles efficient, environmentally friendly, and sustainable, the method is regularly examined. Here, we introduce a brand-new, very effective Cu3TiO4/g-C3N5 photocatalyst for the production of compounds containing chromene-3-carbonitriles. The direct Z-Scheme photo-generated charge transfer mechanism used by the Cu3TiO4/g-C3N5 photocatalyst results in a suppressed rate of electron-hole pair recombination and an increase in photocatalytic activity. Experiments showed that the current method has some advantages, such as using an environmentally friendly and sustainable photocatalyst, having a simple procedure, quick reaction times, a good product yield (82–94%), and being able to reuse the photocatalyst multiple times in a row without noticeably decreasing its photocatalytic performance.

Direct Z-Scheme Heterojunction α-MnO2/BiOI with Oxygen-Rich Vacancies Enhanced Photoelectrocatalytic Degradation of Organic Pollutants under Visible Light

The degradation efficiency of photoelectrocatalytic (PEC) processes for the removal of organic pollutants is highly dependent on the performance of the photoelectroanode catalyst. The design of PEC systems with a direct Z-scheme charge transfer mechanism and visible light excitation is essential to enhance the degradation efficiency of organic compounds. Here, a α-MnO2/BiOI direct Z-scheme heterojunction photocatalyst was successfully synthesized through a convenient and feasible method. It is remarkable that the photoanode exhibited excellent PEC performance under visible light irradiation; a 95% removal rate of tetracycline (TC) pollutants was achieved within 2 h, and it had excellent stability and reusability, which was expected to degrade antibiotics efficiently and environmentally in harsh environments. The presence of oxygen vacancies (OVs) in the α-MnO2/BiOI heterojunction was confirmed by electron spin resonance technique, and the OVs acted as electron traps that contributed substantially to the separation efficiency of photogenerated carriers. ESR characterization showed that the main reactive radicals during TC degradation were •OH and •O2−. By analyzing the intermediates, the possible degradation pathways of TC were further analyzed and a suitable degradation mechanism was proposed. The toxicity changes in the degradation process were explored by evaluating the toxicity of the intermediates. This study provides a new way to enhance the performance of Bi-based semiconductor photocatalysts for the effective degradation of TC in water.

Multifactorial brain storm optimization algorithm based on direct search transfer mechanism and concave lens imaging learning strategy

Multifactorial brain storm optimization algorithm based on direct search transfer mechanism and concave lens imaging learning strategy

Co-catalyst free direct Z–scheme photocatalytic system with simultaneous hydrogen evolution and degradation of organic pollutants

Photocatalytic hydrogen evolution coupled with simultaneous pollutant degradation is a promising but challenging strategy for both wastewater treatment and renewable energy production. In this work, a series of direct Z-scheme heterostructural catalysts, denoted as CeO2/Cu–I-bpy, were designed and constructed by in-situ synthesizing CeO2 nanoparticles on the surface of a coordinate polymer, named Cu–I-bpy. The simultaneous photocatalytic evolution of hydrogen and photo-degradation of organic pollutants was successfully achieved with this hybrid catalyst, even without any co-catalyst. The hybrid catalyst exhibited a 6.9 folds higher hydrogen evolution efficiency than the corresponding individual photo-reduction catalyst (Cu–I-bpy here), and 2.5 times degradation rate of the corresponding individual photo-oxidation catalyst (CeO2 here), after optimizing the CeO2 loading. After extensively characterized via XRD, XPS, Raman spectroscopy, UV–Vis absorption spectroscopy, SEM, TEM, BET, photo-electrochemical method and photoluminescence, it was found that the hybrid catalysts show higher charge separation and transfer efficiency than corresponding individual CeO2 and Cu–I-bpy. Further mechanism investigation via active species trapping, EPR and electron flow experiments indicates a direct Z-scheme charge transfer mechanism in the CeO2/Cu–I-bpy, which not only boosts the photogenerated electron-hole separation efficiency, but also retains the high reduction and oxidation ability the corresponding individual catalyst for hydrogen evolution and pollutant degradation, respectively. This work demonstrates the possibilities of turning waste water into energy resources using carefully designed photocatalytic systems.

In-situ synthesis of direct Z-scheme 2D/2D ZnIn2S4@CeO2 heterostructure toward enhanced photodegradation and Cr(VI) reduction

The rationally designed semiconductor photocatalytic materials have attracted significant attention because of their huge advantages in the use of solar light. Herein, a series of direct Z-scheme heterojunction nanocomposites were synthesized via in situ growth of zinc indium sulfide nanosheets on ceria nanosheets (ZnIn2S4@CeO2) and employed for effective photodegradation and Cr(VI) reduction. Advanced characterizations such as XPS, EPR spectra, and DFT calculations verified that the formation of direct Z-scheme charges transfer mechanism promoted rapid charge separation and retained strong redox capacity. As a result, the optimized ZnIn2S4@CeO2 sample showed significantly promoted photocatalytic removal rates for tetracycline (TC) and Cr(VI) at a 3.7 and 4.5 times enhancement by comparison with the pristine ZnIn2S4, respectively. Additionally, after four consecutive cyclic tests, the as-synthesized nanocomposite exhibited remarkable photocatalytic activity and stability. The present work provides an integrated engineering strategy for Z-scheme photocatalyst systems with high photocatalytic efficiency and extensive applications.