High Photocatalytic Performance Research Articles

Hybrid NiCo2O4-BiOCOOH heterostructure nanocomposite impregnated porous polymer monolith as high-performance visible light photocatalyst for the decontamination of antimicrobial pollutants

We report a first-of-its-kind preparation of a NiCo2O4-BiOCOOH heterostructure as visible light-responsive nanocomposites (NCs) for the fast decontamination of moxifloxacin drug molecules, with longer persistence and non-biodegradability nature that could promote gene-resistance bacteria in aqueous medium. Further, a reusable/recoverable photocatalyst is fabricated through the uniform decoration of NiCo2O4(15 %)-BiOCOOH(85 %), i.e., NB-15 NCs across a tailor-made poly(EGDMA) monolith (PEM) that serves as the host template for the photoactive NCs. The electron microscopy, optical spectroscopy, diffraction, and surface analysis techniques confirm the photocatalyst's superior structural morphology, surface topography, and porosity features that assist in high-performance photocatalysis. The inorganic-organic hybrid photocatalyst exhibits a narrow energy bandgap that promotes ample generation of reactive oxygen species upon visible light irradiation, as confirmed by the electrochemical and spectroscopic analysis. The BET/BJH plot for the photocatalyst reveals a large surface area of 345 m2/g, with voluminous pore distributions (2–80 nm), indicating the coexistence of mesopores-infused macroporous framework that offers better contact/equilibration of the pollutant molecules with the abundantly dispersed photoactive sites. The optimized parameters reveal ≥99.2 % drug dissipation in ≤0.33 h and drug mineralization in ≤2.0 h, using a mere 50 mg of photocatalyst irradiated with a 150 W/cm2 tungsten lamp. The synthesized photocatalyst has a simple/cost-saving procedure that can transform into scalable, cheaper, and eco-friendly products for the real-time monitoring of toxic pollutants. Besides, the photocatalyst exhibits excellent stability and reusability characteristics for efficiently decontaminating organic pollutants, thus highlighting an innovative approach for fabricating high-performance photocatalysts.

Synergistic photocatalytic performance of MoO3:Cu/g-C3N4 heterojunction semiconductor for efficient crystal violet dye degradation: A sustainable approach for environmental remediation

A heterojunction semiconductor of MoO3:Cu in conjunction with g-C3N4 was fabricated using a green synthesis approach facilitated by leaves extract of Murraya paniculata. Numerous methods of characterisation, including XPS, FTIR spectroscopy, XRD, BET, HR-TEM, FE-SEM, EDAX, and UV–visible spectrophotometry were employed to analyse the materials. The results from XRD and HRTEM indicated the highly crystalline nanoparticles with a mean particle size of 5.42 nm for MoO3 nanomaterials with doping of 5.62 nm Cu particles. The two-dimensional g-C3N4 sheeted structure acted as a translucent layer, facilitating self-assembly on the spherical MoO3:Cu nanoparticles, thereby promoting efficient charge flow and enhancing the photodegradation capability of the heterojunction semiconductor. XPS analysis confirmed the presence of Mo, Cu, N, O, and C in the fabricated heterojunction. UV–Visible and PL spectra demonstrated the efficient suppression of exciton annihilation in the heterojunction semiconductor. Remarkably, the heterojunction exhibited a high photocatalytic degradation performance of 97 % for the photodegradation of Crystal violet (CV) dye. Additionally, the effects of pH and dose of catalyst on photodegradation, as well as the recyclability of the catalyst, were evaluated. Kinetic analysis revealed a pseudo first-order reaction with 0.617 min−1 rate constant, while scavenger experiments confirmed the involvement of h+ and .O2− as active species in the degradation process.

Revealing the nontrivial topological surface states of catalysts for effective photochemical carbon dioxide conversion

Topological semimetals with protected surface states mark a new paradigm of research beyond the early landmarks of band-structure engineering, allowing fabrication of efficient catalyst to harness the rich metallic surface states to activate specific chemical processes. Herein, we demonstrate a facile solid-phase method for in-situ doping of Ir at the Os sites in the Os3Sn7, an alloy with topological states, which significantly improves the photocatalytic performance for the reduction of CO2 to CO and CH4. Experimental evidence combined with theoretical calculations reveal that the nontrivial topological surface states greatly accelerate charge-separation/electron-enrichment and adsorption/activation of CO2 molecules, rendering highly efficient reaction channels to stimulate the formation of *COOH and *CO, as well CHO*. This work shows the promise of achieving high photocatalytic performances with synthesizing topological catalysts and provides hints on the design of novel topological catalysts with superior photoactivity towards the CO2 reduction reaction.

Green synthesis of magnetic silver nanocomposite: the photocatalytic performance of nanocomposite to decolorize organic dyes

ABSTRACT The magnetite-silver nanocomposites (Fe3O4-Ag NCs) were synthesized via a facile and green process by Citrus sinensis peel extract. The deposition of silver nanoparticles (NPs) was confirmed by observing an absorption peak at the maximum wavelength at 422 nm in the suspension solution of samples, which is related to silver surface plasmon resonance (SPR). The characteristic diffraction patterns of Fe3O4 and Ag phases were characterized utilizing the XRD patterns and the average size of the crystals was 21 nm. The photocatalytic behavior of Fe3O4-Ag NCs was studied for the destruction of three organic dyes methyl green (MG), methyl orange (MO), and methylene blue (MB) below UV radiation. The effect of the amount of photocatalyst and volume of hydrogen peroxide as an oxidant in the process of dye degradation was also investigated. The complete degradation time of dyes MB, MG, and MO under UV irradiation in the presence of 0.002 g Fe3O4-Ag NCs were 57, 33, and 49 min, respectively. The time of degradation reactions showed the high photocatalytic performance of Fe3O4-Ag NCs. These results proved that the synergistic effect of magnetite in the role of supporting the silver NPs was a significant contribution to the excellent decolorization behavior of Fe3O4-Ag NCs.

Photocatalytic coatings with self-cleaning properties for indoor air treatment

In this work we have studied the photocatalytic and self-cleaning properties of TiO2 layers immobilized on polymeric panels, as passive elements for air treatment. In order to achieve easy scale-up technologies for the preparation of coatings, roller-coating technique was selected, comparing the results with those prepared by dip-coating. Composites were characterized by SAXRD, UV–Vis DRS spectroscopy, profilometry, N2 adsorption–desorption, SEM and AFM microscopy. The adherence of the coating was evaluated according the ASTM D3359 standard adhesive tape test. The photocatalytic properties of the materials were evaluated by the photodegradation of trichloroethylene or formaldehyde, as model volatile organic compounds, in the gas phase. The hydrophilic-hydrophobic properties were measured by studying the in-situ variation of the water contact angle with time and UV-A irradiation. Moreover, the self-cleaning properties were analyzed according to ISO 27448:2009 for oleic acid removal. Although coatings of approximately ca. 250 nm layer thickness can be prepared by both techniques, roller-coating allows the material deposition with a coral-like structure in a single and simple step. Surface roughness was promoted by roller process. The developed materials present high photocatalytic performance for the elimination of both model pollutants in the gas phase. Aging tests under outdoor conditions and Scotch tape test show the stability and resistance of the coatings. In-situ irradiation measurements show the superhydrophilic character of the coatings. Water contact angle lower than 10 ° after 300 min of UV-A irradiation was achieved for oleic acid removal. The combination of TiO2 nanoparticles with different crystal structures and sizes improves the photocatalytic performance. A correlation between the ability for pollutants degradation in gas phase and the self-cleaning properties (in-situ or oleic acid measurements) was determined.

Plasma-induced surface interactions of Pd/SrTiO3 catalyst for improved performance of photocatalytic degradation of toluene

Defective engineering and the addition of noble metal are effective strategies to realize the high photocatalytic performance of SrTiO3 perovskite. Here, the Pd/SrTiO3 catalyst was successfully prepared by the low-temperature plasma treatment coupling with photochemical deposition of metal Pd, which was applied to the photocatalytic degradation of toluene. Compared with single STO, STON, and Pd-STO catalysts, the prepared Pd-STON catalyst shows the excellent UV photocatalytic performance toward toluene degradation, realizing a ca.80 % degradation efficiency within 90 min reaction time. Based on various characterizations, it revealed that plasma treatment promoted the formation of surface oxygen defects, and strengthened the metal-support interaction. The resultant surface oxygen vacancy accelerated the migration rate of photogenerated electrons and the separation of electrons and holes in space, benefiting for superior performance. It is expected that this study can provide new avenues for the rational design of highly efficient photocatalysts for potential practical applications.

Visible light responsive SiO2/g-C3N4/BiOBr/Bi heterojunction photocatalyst for degradation of rhodamine B

For the purpose of alleviating the negative influence of rhodamine B (RhB) abuse on the environment, it is imperative to design a green and efficient photocatalyst for tackling organic dye-contaminated wastewater. Herein, a novel SiO2/g-C3N4/BiOBr/Bi (denoted as Si/CN/BiOB/Bi) photocatalyst with enhanced photodegradation activity has been successfully created. The influence of variable parameters including Bi doping amount, initial concentration of RhB, photocatalyst dosage, and reaction temperature on the photocatalytic performance of Si/CN/BiOB/Bi under visible light illumination are analyzed in detail. Results indicated that the degradation rate constant of RhB over Si/CN/BiOB/Bi-0.5 is 25.1, 18.1, and 2.2 times higher than that of CN, Si/CN, and Si/CN/BiOB, respectively. The Si/CN/BiOB/Bi-0.5 photocatalyst displayed high photocatalytic performance after 5 recycled runs. The improved photocatalytic performance can be attributed to the novel morphology as well as the excellent synergetic effects of Si/CN, BiOBr, and Bi, which enables the catalysts to accelerate the separation of photogenerated carriers. In brief, a new Si/CN/BiOB/Bi photocatalyst has a great application perspective for the purification of RhB wastewater.

Crystal-Defect-Induced Longer Lifetime of Excited States in a Metal-Organic Framework Photocatalyst to Enhance Visible-Light-Mediated CO2 Reduction.

We report the structural defects in Zr-metal-organic framework (MOFs) for achieving highly efficient CO2 reduction under visible light irradiation. A series of defective Zr-MOF-X (X = 160, 240, 320, or 400) are synthesized by acid-regulated defect engineering. Compared to pristine defect-free Zr-MOF (NNU-28), N2 uptake increases for Zr-MOF-X synthesized with the HAc modulator, producing a larger pore space and Brunauer-Emmett-Teller surface area. The pore size distribution demonstrates that defective Zr-MOF-X exhibits mesoporous structures. Electrochemistry tests show that defective Zr-MOF-X possesses a more negative reduction potential and a higher photocurrent responsive signal than that of pristine NNU-28. Consequently, the defective samples exhibit a significantly higher efficiency in the photoreduction of CO2 to formate. Transient absorption spectroscopies manifest that structural defects modulate the excited-state behivior of Zr-MOF-X and improve the photogenerated charge separation of Zr-MOF-X. Furthermore, electron paramagnetic resonance and in-suit X-ray photoelectron spectroscopy provide additional evidence of the high photocatalytic performance exhibited by defective Zr-MOF-X. Results demonstrate that structural defects in Zr-MOF-X also improve the charge transfer, producing abundant Zr(III) catalytically active sites, exhibiting a slower decay process than defect-free Zr-MOF. The long-lifetime Zr(III) species in defective Zr-MOF-X are fully exposed to a high-concentration CO2 atmosphere, thereby enhancing the photocatalytic efficiency of CO2 reduction.

Facile Synthesis of Organic-Inorganic Hybrid Heterojunctions of Glycolated Conjugated Polymer-TiO2-X for Efficient Photocatalytic Hydrogen Evolution.

The utilization of the organic-inorganic hybrid photocatalysts for water splitting has gained significant attention due to their ability to combine the advantages of both materials and generate synergistic effects. However, they are still far from practical application due to the limited understanding of the interactions between these two components and the complexity of their preparation process. Herein, a facial approach by combining a glycolated conjugated polymer with a TiO2-X mesoporous sphere to prepare high-efficiency hybrid photocatalysts is presented. The functionalization of conjugated polymers with hydrophilic oligo (ethylene glycol) side chains can not only facilitate the dispersion of conjugated polymers in water but also promote the interaction with TiO2-X forming stable heterojunction nanoparticles. An apparent quantum yield of 53.3% at 365nm and a hydrogen evolution rate of 35.7mmol h-1 g-1 is achieved by the photocatalyst in the presence of Pt co-catalyst. Advanced photophysical studies based on femtosecond transient absorption spectroscopy and in situ, XPS analyses reveal the charge transfer mechanism at type II heterojunction interfaces. This work shows the promising prospect of glycolated polymers in the construction of hybrid heterojunctions for photocatalytic hydrogen production and offers a deep understanding of high photocatalytic performance by such heterojunction photocatalysts.

Nghiên cứu tổng hợp vật liệu composite SiO2/g-C3N4 cho quá trình quang xúc tác phân hủy rhodamine B

In this study, a visible-light-driven SiO2/g–C3N4 composite was prepared by heating a mixture of SiO2 and urea. The products were characterized by X-ray diffraction (XRD), infrared spectra (IR), scanning electron microscopy (SEM), and ultraviolet–visible diffuse reflectance spectroscopy (UV-Vis DRS). Results indicate that the composite only contained SiO2 and g-C3N4, and the SiO2/g–C3N4 composite had higher photocatalytic activities in the degradation of rhodamine B (82.2%) compared to the pristine g-C3N4 (43.9%) under visible light. The SiO2/g–C3N4 composite is a promising new material for the photodegradation of organic pollutants in wastewater due to its high photocatalytic performance, low cost, and convenient collection for reuse.

Research on the fabrication of nanorod-structured phorphyrin/g-C3N4 as photocatalyst materials for the removal of Cr6+ ions in an aqueous solution

Due to their potential to expand the photon energy harvesting zones and improve charge separation, two semiconductors together have been shown to be a promising technique to increase the photocatalytic activity of photocatalysts. Through the use of monomeric porphyrin molecules and g-C3N4 nanomaterials, self-assembly of the hybird g-C3N4@porrphyrin nanorod materials under CTAB surfactant-assited conditions was demonstrated in this study. SEM, EDS, FTIR, and UV-vis were used to characterize the generated hybrid material. Under simulated sunlight irradiation, the hybrid mateial’s photocatalytic behaviour was examined for the photoreduction of Cr6+ ions. After 100 minutes of reaction time under the simulated solar spectrum, the results showed that the hybrid material demonstrated high photocatalytic performance against, with clearance percentage of almost 100%. The prepared photocatalyst was also highly stable with the reduction of Cr6+ removal efficiency of less than 10% after 4 cycles of photocatalytic testing.

Photocatalytic reaction pathways and mechanisms investigation for effective organic pollution degradation via in-situ construction of BiOCl/UiO66-NH2 heterostructure

Constructing heterostructured photocatalysts is a desirable strategy for the enhanced degradation performance of pollutants from wastewater. In this work, BiOCl/UiO66-NH2 photocatalysts were constructed by in-situ solvothermal method. The composites presented enhanced photocatalytic activity for the degradation of Ciprofloxacin (CIP), Tetracycline hydrochloride (TC) and Rhodamine B (RhB) under simulated sunlight. The formation of the porous structure via the introduction of UiO66-NH2 not only enhances the adsorption ability of the catalyst but also promotes light harvesting, which enables the samples to exhibit high photocatalytic performance. In addition, the probable photodegradation pathways and mechanisms were studied in detail. This work provides an effective route for removing various pollutants in wastewater with heterojunction photocatalysts.

Rational engineering β-Bi2O3/Bi2O2CO3 heterojunction photocatalyst from tetragonal BiOCl microrods displaying high photocatalytic performance

A tetragonal cylindrical Bi2O2CO3 self-assembled from nanosheets was formed in situ by interlayered substitution using BiOCl column as the precursor. The β-Bi2O3/Bi2O2CO3 heterojunction was synthesized then by calcining the as-formed Bi2O2CO3. The β-Bi2O3/Bi2O2CO3 showed excellent photocatalytic performance with k values (the apparent rate constants) were 0.1738 and 0.1162min−1, respectively, for degrading 50 mg/L Cr(VI) solution and 10 mg/L MO. Both free radical trapping and electron paramagnetic resonance spectrometer measurements proved that superoxide radical (O2−) was key active species photodegradation of Cr(VI) and MO. The photoluminescent spectroscopy and electrochemical impedance indicated that the β-Bi2O3/Bi2O2CO3 heterojunction had a high separation efficiency of photogenerated charge carriers. This work provides a simple anion exchange synthesis method, which will inspire many researchers to develop high-performance catalysts.

2D/2D homojunction-mediated charge separation: Synergistic effect of crystalline C3N5 and g-C3N4 via electrostatic self-assembly for photocatalytic hydrogen and benzaldehyde production

Homojunction engineering is a promising modification strategy to improve charge carrier separation and photocatalytic performance of carbon nitrides. Leveraging intrinsic heptazine/triazine phase and face-to-face contact, crystalline C3N5 (CC3N5) was combined with protonated g-C3N4 (pgCN) through electrostatic self-assembly to achieve robust 2D/2D homojunction interfaces. The highest photocatalytic performance was obtained through crystallinity and homojunction engineering, by controlling the pgCN:CC3N5 ratio. The 25:100 pgCN:CC3N5 homojunction (25CgCN) had the highest hydrogen production (1409.51 μmol h−1) and apparent quantum efficiency (25.04%, 420 nm), 8-fold and 180-fold higher than CC3N5 and pgCN, respectively. This photocatalytic homojunction improves benzaldehyde and hydrogen production activity, retaining 89% performance after 3 cycles (12 h) on a 3D-printed substrate. Electron paramagnetic resonance demonstrated higher ·OH−, ·O2− and hole production of irradiated 25CgCN, attributed to crystallinity and homojunction interaction. Thus, electrostatic self-assembly to couple CC3N5 and pgCN in a 2D/2D homojunction interface ameliorates the performance of multifunctional solar-driven applications.

Synergistic photocatalytic activity of metal chalcogenides (MoS2)-Modified Silver silicate (Ag6Si2O7) nanocomposites for dyes degradation

A recent research focus aimed at enhancing photocatalysis efficiency by tackling rapid charge carrier recombination resulted in a significant breakthrough. Through the synthesis of a composite heterostructure comprising Ag6Si2O7/MoS2 using a hydrothermal approach, the creation of the AM-4 composite marked a notable advancement. AM-4 demonstrated remarkable photonic efficiency enhancements, achieving impressive degradation rates of 97.31% for rhodamine B and 98.31% for methylene blue within a mere 45-minute timeframe. Surpassing pure Ag6Si2O7 by 26.65 times in rate constant, the superior performance of AM-4 was supported by a thorough examination of its physicochemical and electrochemical properties, reinforcing a proposed mechanism for its enhanced efficacy. Evaluation of its durability and reusability through XRD, BET, and XPS analyses further confirmed the composite’s exceptional performance. This study deepens our comprehension of the Ag6Si2O7/MoS2 composite and offers valuable insights for advancing high-performance photocatalysis applications.

Tailored Polymeric Carbon Nitride Coupled with Bi2O3 for Constructing Z‐Scheme Heterojunction with Enhanced Photocatalytic Activity

AbstractThe great demand for visible‐light‐induced catalysts with high photocatalytic performance has stimulated extensive interest in constructing g‐C3N4‐based Z‐Scheme heterojunctions. In this research work, the g‐C3N4/Bi2O3 Z‐Scheme heterojunction by precipitation‐hydrothermal method was constructed, and characterized by various techniques. The g‐C3N4/Bi2O3‐1 composite exhibited a transient photocurrent response approximately 7 and 5 times higher than that of bare g‐C3N4 and Bi2O3, respectively, and showed higher visible photocatalytic activity with 99.8 % degradation of methylene blue (MB) within 75 min. Meanwhile, the pH effect on the photocatalytic degradation of MB was investigated. Radicals trapping experiments showed that •OH free radical played a predominant role for the degradation of MB, EPR analysis confirmed the presence of superoxide radicals, which combined with the band structure of the composites, confirmed the Z‐Scheme of the heterojunction. A possible mechanism for photocatalytic degradation of MB dyes in g‐C3N4/Bi2O3‐1 composites was also proposed. This study provided a new avenue for the development of novel g‐C3N4‐based Z‐Scheme heterojunction materials with prospective applications in the fields of energy and environment.

In-situ Hf/Zr co-doped Fe2O3 nanorod decorated with CuOx/CoOx: Enhanced photocatalytic performance for antibacterial and organic pollutants

Herein, we successfully synthesized Hf/Zr co-doping on Fe2O3 nanorod photocatalyst by a hydrothermal process and quenching methods. The synergistic roles of Hf and Zr double-doping on the bacteria inactivation test and decomposition of organic pollutants were investigated in detail for the 1 wt% CoOx loaded Hf/Zr–Fe2O3 NRs and CuOx/CoOx loaded Hf/Zr–Fe2O3 NRs photocatalyst. Initially, the rod-like porous morphology of the Hf/Zr-doped Fe2O3 NRs was produced via a hydrothermal method at various Hf co-doping (0, 2, 4, 7 and 10)%. Further, CoOx and CuOx loaded by a wet impregnation approach on the Hf/Zr–Fe2O3 NRs and a highly photoactive Hf(4)/Zr–Fe2O3 [CoOx/CuOx] NRs photocatalyst were developed. After the Hf(4)/Zr–Fe2O3 [CoOx/CuOx] NRs photocatalyst treatment, the Bio–TEM imagery of bacterial cells showed extensive morphological deviations in cell membranes. Hf(4)/Zr–Fe2O3 NR achieved 84.1% orange II degradation upon 3 h illumination, which is higher than that of Hf–Fe2O3 and Zr–Fe2O3 (68.7 and 73.5%, respectively). Additionally, the optimum sample, Hf(4)/Zr–Fe2O3 [CoOx/CuOx] photocatalyst, exhibited 95.5% orange II dye degradation after light radiation for 3 h. Optimized Hf(4)/Zr–Fe2O3 [CoOx/CuOx] catalysts exhibited 99.9% and 99.7% inactivation of E. coli and S. aureus with 120 min, respectively. Further, scavenger experiments revealed that the electrons are the primary responsible species for photocatalytic kinetics. This work will provide a rapid method for the development of high photocatalytic performance materials for bacterial disinfection and organic degradation.

0D/1D CuO-Cu2O/ZnO p-n heterojunction with high photocatalytic activity for the degradation of dyes and Naproxen

The development of highly active photocatalysts with broad spectrum response is of paramount importance for photocatalytic applications. Herein, heterostructured CuO-Cu2O/ZnO photocatalysts were prepared in a single step and under mild conditions using a photodeposition process which allows to deposit CuO-Cu2O particles with an average size of ca. 2.4 nm on the surface of ZnO nanorods. The p-n heterojunction built between CuO-Cu2O and ZnO allows to increase both the visible light response of the photocatalyst and the charge separation. The CuO-Cu2O(10%)/ZnO catalyst exhibits the highest activity for the degradation of dyes (Rhodamine B and Remazol Brilliant Blue R) and of Naproxen under simulated solar light irradiation. Based on scavenging experiments, holes, superoxide radicals O2●- and singlet oxygen 1O2 are the dominant species involved in the photocatalytic degradation and a mechanism is proposed. Due to its high stability and photocatalytic performance in various water matrices, the CuO-Cu2O(10%)/ZnO nanohybrid is of high potential for the large scale remediation of organic pollutants in wastewater.

Sustainable in situ synthesis of silver/titanium dioxide/organofunctional trialkoxysilane nanocomposite coatings on cotton fabric to tailor superior multifunctional protective properties

Multifunctional properties are crucial for the production of high-quality technical textiles. In this study, a cotton fabric with simultaneously superior UV-protection, self-sterilisation, photocatalytic self-cleaning and flame retardant properties was produced using a sol–gel/hydrothermal process, in which titanium(IV) isopropoxide (TTIP) as a titanium dioxide (TiO2) precursor was combined for the first time with mixtures of organofunctional trialkoxysiloxanes, i.e., 3-(trihydroxysilyl)propyl methylphosphonate (TPMP) as a P-based flame retardant and dimethyloctadecyl [3-(trimethoxysilyl)propyl]ammonium chloride (SiQAC) or aminopropyltriethoxysilane (APTES) as the antimicrobial, biobarrier-forming precursors. The latter was used in two increased concentrations of APTES1 and APTES2. A sol–gel/hydrothermal approach was employed with a small amount of silver nitrate (AgNO3) added during the hydrothermal treatment to produce Ag-loaded TiO2. The results of scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), X-ray diffraction spectroscopy (XRD), inductively coupled plasma mass spectroscopy (ICP MS) and Fourier-transform infrared spectroscopy (FT-IR) confirmed the successful functionalisation of TiO2 by TPMP, SiQAC and APTES through the formation of Si–O–Ti bonds and the well-dispersed Ag/TiO2/TPMP/SiQAC, Ag/TiO2/TPMP/APTES1 and Ag/TiO2/TPMP/APTES2 coatings on the surface of the cotton fabric. The type of biobarrier-forming precursor significantly influenced the formation of the Ag species after the Ag loading of TiO2. The presence of SiQAC induced the formation of AgCl crystals, while APTES controlled the formation of silver nanoparticles (Ag NPs), which was more pronounced at the lower APTES1 concentration. The interactions between the coating components significantly influenced the functional protection performance, with the highest level of cooperation achieved in the Ag/TiO2/TPMP/SiQAC and Ag/TiO2/TPMP/APTES1 coatings, which exhibited the best overall multifunctionality, albeit with certain drawbacks. While the Ag/TiO2/TPMP/APTES1 coating provided excellent UV protection for the cotton, this was only improved by the Ag/TiO2/TPMP/SiQAC coating. At the same time, the Ag/TiO2/TPMP/APTES1 coating impaired the development of the char barrier by TPMP, which is due to the formation of Ag NPs. Nevertheless, both coatings showed high photocatalytic self-cleaning performance, complete self-sterilisation activity and improved burning behaviour.

SiQDs-mediated highly efficient hole transfer for photocatalytic overall water splitting over Cu-doped ZnIn2S4

Sluggish hole transfer and the resulting pronounced charge recombination hinder the efficiency of photocatalytic overall water splitting. Herein, we present Si quantum dots (SiQDs) as hole transporter to construct SiQDs/Cu-doped ZnIn2S4 heterojunction photocatalysts (Cu0.48SZ) for overall water splitting. Under visible light illumination, Cu0.48SZ exhibits highly stable overall water-splitting activity of 210 μmol g−1 h−1 H2 and 97 μmol g−1 h−1 O2 with an apparent quantum yield (AQY) of 2.57 % at 420 nm. Results demonstrate that the synergy of SiQDs and Cu doping enhances carrier-separation efficiency and reduce surface kinetic barriers, leading to high photocatalytic performance. The presence of SiQDs effectively accelerates the transfer of photoexcited holes and avoids the self-oxidation of ZnIn2S4, favoring water oxidation. The Cu doping increases the electron density around the S atoms of ZnIn2S4 and thus promotes water reduction. This work extends the application of SiQDS as efficient hole transporter for photocatalytic overall water splitting.