Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 46
Filtrar
Más filtros











Base de datos
Intervalo de año de publicación
1.
Mikrochim Acta ; 191(7): 364, 2024 06 03.
Artículo en Inglés | MEDLINE | ID: mdl-38831034

RESUMEN

CdIn2S4 and zinc tetrakis(4-carboxyphenyl)porphyrin (ZnTCPP) were synthesized by hydrothermal method, and an organic dye-sensitized inorganic semiconductor ZnTCPP/CdIn2S4 type II heterojunction was constructed on a fluorine-doped tin oxide (FTO) substrate electrode. A sandwich immunostructure for signal-attenuation photoelectrochemical (PEC) detection of cardiac troponin I (cTnI) was constructed using the ZnTCPP/CdIn2S4/FTO photoanode and a horseradish peroxidase (HRP)-ZnFe2O4-Ab2-bovine serum albumin (BSA) immunolabeling complex. The bioenzyme HRP and the HRP-like nanozyme ZnFe2O4 can co-catalyze the oxidation of 4-chloro-1-naphthol (4-CN) by H2O2 to produce an insoluble precipitate on the photoanode, thus notably reducing the anodic photocurrent for quantitative determination of cTnI. Under the optimal conditions, the photocurrent at 0 V vs. SCE in 0.1 M phosphate buffer solution (pH 7.40) containing 0.1 M ascorbic acid was linear with the logarithm of cTnI concentration from 500 fg mL-1 to 50.0 ng mL-1, and the limit of detection (LOD, S/N = 3) is 0.15 pg mL-1. Spiked recoveries were 95.1% ~ 104% for assay of cTnI in human serum samples.


Asunto(s)
Técnicas Electroquímicas , Límite de Detección , Compuestos de Estaño , Troponina I , Troponina I/sangre , Humanos , Técnicas Electroquímicas/métodos , Inmunoensayo/métodos , Compuestos de Estaño/química , Catálisis , Peroxidasa de Rábano Silvestre/química , Naftoles/química , Metaloporfirinas/química , Electrodos , Peróxido de Hidrógeno/química , Albúmina Sérica Bovina/química , Procesos Fotoquímicos , Animales , Técnicas Biosensibles/métodos , Semiconductores , Bovinos , Sulfuros/química , Porfirinas/química
2.
Molecules ; 29(12)2024 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-38930864

RESUMEN

The low light absorption efficiency has seriously hindered the application of two-dimensional transition metal dichalcogenide (TMDC) nanosheets in the field of optoelectronic devices. Various approaches have been used to improve the performance of TMDC nanosheets. Preparation of one-dimensional TMDC nanoscrolls in combination with photoactive materials has been a promising method to improve their properties recently. In this work, we report a facile method to enhance the optoelectronic performance of TMDC nanoscrolls by wrapping the photoactive organic dye rhodamine (R6G) into them. After R6G molecules were deposited on monolayer TMDC nanosheets by the solution method, the R6G/MoS2 nanoscrolls with lengths up to hundreds of microns were prepared in a short time by dropping a mixture of ammonia and ethanol solution on the R6G/MoS2 nanosheets. The as-obtained R6G/MoS2 nanoscrolls were well characterized by optical microscopy, atomic force microscopy, Raman spectroscopy, and transmission electron microscopy to prove the encapsulation of R6G. There are multiple type II heterojunction interfaces in the R6G/MoS2 nanoscrolls, which can promote the generation of photo-induced carriers and the following electron-hole separation. The separated electrons were transported rapidly along the axial direction of the R6G/MoS2 nanoscrolls, which greatly improves the efficiency of light absorption and photoresponse. Under the irradiation of an incident 405 nm laser, the photoresponsivity, carrier mobility, external quantum efficiency, and detectivity of R6G/MoS2 nanoscrolls were enhanced to 66.07 A/W, 132.93 cm2V-1s-1, 20,261%, and 1.25 × 1012 cm·Hz1/2W-1, which are four orders of magnitude higher than those of monolayer MoS2 nanosheets. Our work indicates that the R6G/TMDC hybrid nanoscrolls could be promising materials for high-performance optoelectronic devices.

3.
Chemosphere ; 352: 141353, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38307337

RESUMEN

The release of industrial effluents, comprising of organic dyes, antibiotics, and heavy metals poses substantial environmental and ecological threats. Among the different approaches, the utilization of heterogeneous photocatalysis based on semiconducting metal oxides is of paramount important to removal of organic ( MB dye and TC antibiotic) and inorganic pollutants ( Cr (VI) ) in wastewater. In this work, a new approach for creating type-II heterojunction photocatalysts named xNiCo2O4/BiVO4 or BNC is suggested. The as-prepared samples were thoroughly examined by means of several sophisticated analytical tools to investigate their physicochemical properties. These composites were utilized in the decomposition of MB dye, TC drug and the reduction of Cr (VI) under visible light irradiation. According to the findings, the creation of type-II heterojunction at BiVO4-NiCo2O4 interface greatly improved charge transportation while successfully preventing electron-hole recombination. Among the various composites studied, BNC-2 demonstrated an enhanced photocatalytic activity towards degradation of MB and TC, which were found to be 91 % over a period of 150 min and 95 % within only 60 min, respectively. Moreover, the photocatalytic reduction of Cr (VI) was accomplished 96 % within just 25 min. Additionally, it is discovered that BNC-2 displayed promising photostability and recyclability with a retention of >90 % after five consecutive cycles. The enhanced photocatalytic activity of BNC-2 is evidently attributed to the expedited separation and transfer of charges, as proven by photocurrent measurement, photoluminescence and electrochemical impedance spectroscopy analyses. Hence, the current amalgamation of NiCo2O4 and BiVO4 heterojunction composite has paved novel paths towards photocatalytic removal of organic as well as inorganic contaminants.


Asunto(s)
Bismuto , Contaminantes Ambientales , Bismuto/química , Luz , Antibacterianos , Óxidos/química
4.
J Colloid Interface Sci ; 659: 776-787, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38215614

RESUMEN

Photocatalytic selective oxidation of alcohols into aldehydes and H2 is a green strategy for obtaining both value-added chemicals and clean energy. Herein, a dual-purpose ZnIn2S4@CdS photocatalyst was designed and constructed for efficient catalyzing benzyl alcohol (BA) into benzaldehyde (BAD) with coupled H2 evolution. To address the deep-rooted problems of pure CdS, such as high recombination of photogenerated carriers and severe photo-corrosion, while also preserving its superiority in H2 production, ZnIn2S4 with a suitable band structure and adequate oxidizing capability was chosen to match CdS by constructing a coupled reaction. As designed, the photoexcited holes (electrons) in the CdS (ZnIn2S4) were spatially separated and transferred to the ZnIn2S4 (CdS) by electrostatic pull from the built-in electric field, leading to expected BAD production (12.1 mmol g-1 h-1) at the ZnIn2S4 site and H2 generation (12.2 mmol g-1 h-1) at the CdS site. This composite photocatalyst also exhibited high photostability due to the reasonable hole transfer from CdS to ZnIn2S4. The experimental results suggest that the photocatalytic transform of BA into BAD on ZnIn2S4@CdS is via a carbon-centered radical mechanism. This work may extend the design of advanced photocatalysts for more chemicals by replacing H2 evolution with N2 fixation or CO2 reduction in the coupled reactions.

5.
J Environ Sci (China) ; 134: 21-33, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37673530

RESUMEN

The construction of heterophase junctions by rutile-anatase TiO2 is considered an effective strategy for toluene degradation, but the photogenerated electron utilization is still insufficient. In this study, the formation of type-II heterojunction by the encapsulation of Materials of Institut Lavoisier (MIL-101) by anatase is performed, and then the heterophase junction is further constructed to improve the catalytic performance of the photocatalyst. The enhancement of photocatalytic performance depends on the encapsulation of MIL-101 by anatase, the light absorption capacity of anatase, and the contact area of two heterojunctions. Photogenerated electrons are transferred to oxygen vacancies of anatase and promoting the generation of oxygen-containing radicals. The material certifies the synergistic effect of the heterophase junction and heterojunction design and provides a theoretical basis for application in the degradation of volatile organic compounds.


Asunto(s)
Gases , Oxígeno , Especies Reactivas de Oxígeno , Tolueno
6.
Nanotechnology ; 34(50)2023 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-37722361

RESUMEN

Semiconductor photocatalysis has attracted the attention of a wide audience for its outstanding capabilities in water purification and energy conversion. Herein, a noble-metal-free nanoheterojunction is created by planting zero-dimensional (0D) CdS nanograins, of 10-20 nm in size, on the surface of 2D SnS2nanosheets (NSs) using anin situchemical bathing deposition process, where SnS2NSs have an average diameter of 400 nm and thicknesses of less than 20 nm. The possible formation mechanism of the CdS/SnS2(CS/SS) heterogeneous nanostructure is elaborated upon. The catalytic activities over CS/SS nanocomposites for the photodegradation of organic dye and hydrogen evolution from photolysis water splitting are examined under visible light irradiation. The apparent rate constant (k) of the optimal CS/SS-3 composite in the decontamination of methylene blue (MB) is up to 3.34 and 1.87 times as high as that of pristine SnS2and pure CdS counterparts, respectively. The optimized CS/SS-3 sample consistently achieves the highest photocatalytic hydrogen production rate, at 10.3 and 5.7 folds higher than that of solo SnS2and CdS panels, respectively. The boosted photocatalytic capacities of CdS/SnS2heterostructures are essentially attributed to the formation of the closely interfacial incorporation of CdS and SnS2semiconductors, resulting in the effective charge transportation and spatial separation of the photoinduced electron-hole pairs. Furthermore, the traditional type-II charge transfer pathway is proposed based on the perfect band structure and the free radical experiment results.

7.
Environ Sci Pollut Res Int ; 30(44): 99675-99693, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37620699

RESUMEN

Photodegradation of paraquat herbicide was assessed over several TiO2-WO3 heterojunctions embedded in the diatomite matrix. The characterization results indicated that WO3 embedding in the TiO2 decorated-diatomite matrix could not only enhance the adsorption capacity, visible-light response, and distribution of semiconductor species but also lessen the recombination rate and band gap energy. These characteristics were more noticeable as 5 wt.% of WO3 was embedded. Despite better optical properties of immobilized TiO2-WO3 nanocomposites, overloading WO3 generally alleviates the synergetic effect of tungsten due to surface coverage of diatomite matrix and, subsequently, the significant attenuation of textural properties, more formation of agglomerations and defects as trapping centers in the oxidation sites of heterostructures, and also, less likely of forming TiO2-WO3 heterojunction. In accordance with characterization results, the highest UV-photodegradation of paraquat was attained over heterostructured nanocomposite containing 5 wt.% WO3 (T25-W5/Di). The effects of significant operating parameters were also investigated, modeled, and optimized using response surface methodology (RSM)-central composite design (CCD). Under optimized operation conditions, the experimental removal efficiency of paraquat reached 97.1 and 80% using UV and simulated solar light, respectively. Moreover, the reusability results confirm the sustained activity of the T25-W5/Di nanocomposite.


Asunto(s)
Herbicidas , Paraquat , Fotólisis
8.
Environ Sci Pollut Res Int ; 30(60): 124992-125005, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37498427

RESUMEN

Graphene quantum dots (GQDs), a new solid-state electron transfer material was anchored to nitrogen-doped TiO2 via sol gel method. The introduction of GQDs effectively extended light absorption of TiO2 from UV to visible region. GQD-N-TiO2 demonstrated lower PL intensity at excitation wavelengths of 320 to 450 nm confirming enhanced exciton lifespan. GQD-N-TiO2-300 revealed higher surface area (191.91m2 g-1), pore diameter (1.94 nm), TEM particle size distribution (4.88 ± 1.26 nm) with lattice spacing of 0.45 nm and bandgap (2.91 eV). In addition, GQDs incorporation shifted XPS spectrum of Ti 2p to lower binding energy level (458.36 eV), while substitution of oxygen sites in TiO2 lattice by carbon were confirmed through deconvolution of C 1 s spectrum. Photocatalytic reaction followed the pseudo first order reaction and continuous reductions in apparent rate constant (Kapp) with incremental increase in RB5 concentration. Langmuir-Hinshelwood model showed surface reaction rate constants KC = 1.95 mg L-1 min-1 and KLH = 0.76 L mg-1. The active species trapping, and mechanism studies indicated the photocatalytic decolorization of RB5 through GQD-N-TiO2 was governed by type II heterojunction. Overall, the photodecolorization reactions were triggered by the formation of holes and reactive oxygen species. The presence of •OH, 1O2, and O2• during the photocatalytic process were confirmed through EPR analysis. The excellent photocatalytic decolorization of the synthesized nanocomposite against RB5 can be ascribed to the presence of GQDs in the TiO2 lattice that acted as excellent electron transporter and photosensitizer. This study provides a basis for using nonmetal, abundant, and benign materials like graphene quantum dots to enhance the TiO2 photocatalytic efficiency, opening new possibilities for environmental applications.


Asunto(s)
Grafito , Puntos Cuánticos , Luz , Nitrógeno
9.
Materials (Basel) ; 16(10)2023 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-37241258

RESUMEN

Photocatalytic degradation is an environmentally friendly way to eliminate environmental pollution. Exploring a photocatalyst with high efficiency is essential. In the present study, we fabricated a Bi2MoO6/Bi2SiO5 heterojunction (BMOS) with intimate interfaces via a facile in situ synthesis method. The BMOS had much better photocatalytic performance than pure Bi2MoO6 and Bi2SiO5. The sample of BMOS-3 (3:1 molar ratio of Mo:Si) had the highest removal efficiency by the degradation of Rhodamine B (RhB) up to 75% and tetracycline (TC) up to 62% within 180 min. The increase in photocatalytic activity can be attributed to constructing high-energy electron orbitals in Bi2MoO6 to form a type II heterojunction, which increases the separation efficiencies of photogenerated carriers and transfer between the interface of Bi2MoO6 and Bi2SiO5. Moreover, electron spin resonance analysis and trapping experiments showed that the main active species were h+ and •O2- during photodegradation. BMOS-3 maintained a stable degradation capacity of 65% (RhB) and 49% (TC) after three stability experiments. This work offers a rational strategy to build Bi-based type II heterojunctions for the efficient photodegradation of persistent pollutants.

10.
Materials (Basel) ; 16(10)2023 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-37241505

RESUMEN

Water pollution is a significant social issue that endangers human health. The technology for the photocatalytic degradation of organic pollutants in water can directly utilize solar energy and has a promising future. A novel Co3O4/g-C3N4 type-II heterojunction material was prepared by hydrothermal and calcination strategies and used for the economical photocatalytic degradation of rhodamine B (RhB) in water. Benefitting the development of type-II heterojunction structure, the separation and transfer of photogenerated electrons and holes in 5% Co3O4/g-C3N4 photocatalyst was accelerated, leading to a degradation rate 5.8 times higher than that of pure g-C3N4. The radical capturing experiments and ESR spectra indicated that the main active species are •O2- and h+. This work will provide possible routes for exploring catalysts with potential for photocatalytic applications.

11.
Small ; 19(38): e2303319, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37194967

RESUMEN

Photo-rechargeable (solar) battery can be considered as an energy harvesting cum storage system, where it can charge the conventional metal-ion battery using light instead of electricity, without having other parasitic reactions. Here a two-electrode lithium-ion solar battery with multifaceted TiS2 -TiO2 hybrid sheets as cathode. The choice of TiS2 -TiO2 electrode ensures the formation of a type II semiconductor heterostructure while the lateral heterostructure geometry ensures high mass/charge transfer and light interactions with the electrode. TiS2 has a higher lithium binding energy (1.6 eV) than TiO2 (1.03 eV), ensuring the possibilities of higher amount of Li-ion insertion to TiS2 and hence the maximum recovery with the photocharging, as further confirmed by the experiments. Apart from the demonstration of solar solid-state batteries, the charging of lithium-ion full cell with light indicates the formation of lithium intercalated graphite compounds, ensuring the charging of the battery without any other parasitic reactions at the electrolyte or electrode-electrolyte interfaces. Possible mechanisms proposed here for the charging and discharging processes of solar batteries, based on the experimental and theoretical results, indicate the potential of such systems in the forthcoming era of renewable energies.

12.
Environ Sci Pollut Res Int ; 30(25): 67647-67661, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-37118391

RESUMEN

Zirconium-based porphyrin metal organic frameworks (Zr-PMOFs) had attracted attention in the field of photocatalysis in recent years. However, the recombination of photogenerated carriers of monomer PMOF limits its performance of photocatalytic organic pollutants degradation. Metal sulfide has a suitable visible band gap, which can form a heterojunction with MOF materials to enhance the photocatalytic efficiency of MOF. Therefore, a typical metal sulfide semiconductor ZnIn2S4 (ZIS) was introduced into a Zr-MOF (MOF-525) by solvothermal method to prepare a series of ZIS/MOF-525 (ZIS/MOF-525-1, ZIS/MOF-525-2, ZIS/MOF-525-3 and ZIS/MOF-525-4) composite photocatalysts in this work. The results of characterization analysis, optical analysis and electrochemical analysis showed that the interface of ZIS/MOF-525 formed a typical type-II heterojunction, which accelerated the electron transport rate and effectively inhibited the recombination of photogenerated e- and h+ in MOF-525. The optimal removal efficiency of tetracycline (TC) by ZIS/MOF-525-3 (the mass of MOF-525 is 30 mg) reached 93.8% under 60 min visible light illumination, which was greater than that of pure MOF-525 (37.2%) and ZnIn2S4 (70.0%), and it still maintained good stability after five cycles reusing experiment. This work provides feasible insight for the preparation of novel and efficient PMOF-based photocatalysts in the future.


Asunto(s)
Porfirinas , Tetraciclina , Antibacterianos , Transporte de Electrón , Sulfuros
13.
Mikrochim Acta ; 190(5): 192, 2023 04 26.
Artículo en Inglés | MEDLINE | ID: mdl-37099090

RESUMEN

AgBiS2 was hydrothermally synthesized, In2O3 was synthesized by hydrothermal method and calcination, and the type-II In2O3/AgBiS2 heterojunction material of an optimized composition ratio was cast-coated on a fluorine-doped tin oxide (FTO) slice to fabricate an In2O3/AgBiS2/FTO photoanode. The signal-attenuated photoelectrochemistry sandwich immunoassay of squamous cell carcinoma antigen (SCCA) was realized on this photoanode, on the basis of a bovine serum albumin/secondary antibody/CuO nanoparticles/nitrogen-doped porous carbon-ZnO bionanocomposite that can competitively absorb light and deplete the electron donor ascorbic acid as well as show the steric hindrance and p-n quenching effects. Under the optimized conditions (e.g., at a bias of 0 V vs. SCE), the photocurrent was linear with the common logarithm of SCCA concentration from 2.00 pg mL-1 to 50.0 ng mL-1, with a limit of detection (LOD) of 0.62 pg mL-1 (S/N = 3). The immunoassay of SCCA in human serum samples gave satisfactory recovery (92.0~103%) and relative standard deviation (5.1~7.8%) results.


Asunto(s)
Óxido de Zinc , Humanos , Óxido de Zinc/química , Carbono , Nitrógeno , Porosidad , Inmunoensayo/métodos
14.
Chemosphere ; 322: 138221, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36828116

RESUMEN

FT-x composites with core-shell structure (FT = FeS2@TiO2, x represents the mass ratio of the used FeCl3·6H2O to MIL-125) were fabricated by a hydrothermal method using MIL-125(Ti) as a self-sacrificing template. Both the photo-Fenton activity and stability of the FT-1 were improved greatly in comparison with its counterparts due to the unique core-shell structure and synergistic effect between FeS2 and TiO2. Especially, the Fe leaching concentration of FT-1 was approximately 1/10 of the individual FeS2, benefiting from the protection effect of TiO2 shell. Under dark condition, the formed FeOOH occupied active sites and inhibited iron cycle as well as H2O2 decomposition, leading to the inactivation of FT-1. UV light irradiation not only boosted the catalytic activity but also prevented the FT-1 from reactivity decline owning to the regeneration of Fe2+ by photogenerated electrons and continuous generation of ·OH. Experimental and DFT calculation results indicated that a type-II heterojunction was formed, in which photogenerated electrons were transferred from FeS2 core to TiO2 shell, accelerating charge separation and further boosting sulfamethoxazole (SMX) degradation. FT-1 displayed outstanding photo-Fenton activity in wide pH ranged from 2 to 6 and good anti-interfering ability toward impurities in water matrix. Besides, the reusability of FT-1 was good, in which 90% SMX degradation was maintained even after 5 runs. Noteworthy, the photo-Fenton activity was recovered via a revulcanization process, in which FeOOH was completely transformed into FeS2. This founding provided insights for the design and construction of heterojunction with both excellent photo-Fenton activity and stability.


Asunto(s)
Peróxido de Hidrógeno , Sulfametoxazol , Peróxido de Hidrógeno/química , Hierro/química , Titanio/química
15.
Chemosphere ; 320: 138113, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36773679

RESUMEN

For opening a way to synthesize novel metal-free catalysts and clarifying the photodegradation performance difference of photoactive species (such as ·O2-, h+), a series of metal-free photocatalysts have been synthesized by using different existing forms of the same materials (boron carbon nitride (BCN) and boron carbon nitride-citric acid quantum dot (BCQD)) as precursors via calcinating their mixture at 350 °C. BCQD has good fluorescence and up-conversion fluorescence performance. BCN/BCQD-350 has the highest removal efficiency (90%, including adsorption 60% and photodegradation 30%) for tetracycline (TC) among all samples under visible light irradiation. TC adsorption by BCN/BCQD-350 conforms to pseudo-second-order kinetic and Langmuir isotherm models. TC photodegradation by BCN/BCQD-350 conforms to type II heterojunction mechanism. Photoactive species capture experiments suggest that·O2- makes a higher contribution for TC photodegradation, followed by h+, ·OH, 1O2 and e-. From LC-MS results, TC photodegradation is initiated by the dehydration step. TC dehydration activated by ·O2- has the lowest barrier (43.4 kcal/mol) than that (50.1 kcal/mol) activated by h+, that (64.8 kcal/mol) without the activation by photoactive species. TC removal rate of BCN/BCQD-350 (0.01563 min-1) is higher than that of g-C3N4, P25 (TiO2), BNPA, BCNPA, etc. Furthermore, BCN/BCQD-350 can also photodegrade TC under infrared light irradiation (λ > 800 nm).


Asunto(s)
Boro , Puntos Cuánticos , Humanos , Deshidratación , Tetraciclina , Antibacterianos , Metales , Luz , Catálisis
16.
Nanomaterials (Basel) ; 12(24)2022 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-36558283

RESUMEN

It is of great importance to promote charge separation in photocatalysts for enhanced photocatalytic activity under visible light irradiation. In this work, a type-II heterostructured photocatalyst was constructed by compositing phosphorus-doped g-C3N4 (P-CN) and Rh-doped SrTiO3 (Rh-STO) via a thermal calcination treatment. A series of characterizations were conducted to investigate the structure of heterostructured P-CN/Rh-STO. It was found that Rh-STO interacted with in situ generated P atoms from the decomposition of P-CN during the calcination process, thus leading to the formation of heterojunction of P-CN/Rh-STO. Compared with the single component, i.e., P-CN or Rh-STO, the obtained P-CN/Rh-STO showed superior photocatalytic activity to that of both P-CN and Rh-STO due to the effective charge separation across the heterojunction between P-CN and Rh-STO.

17.
ACS Appl Mater Interfaces ; 14(40): 45392-45402, 2022 Oct 12.
Artículo en Inglés | MEDLINE | ID: mdl-36179059

RESUMEN

Bismuth vanadate (BiVO4) has been considered as a promising photoelectrocatalytic (PEC) semiconductor, but suffers from severe hole recombination, attributed to the short hole-diffusion length and the low carrier mobility. Herein, a type-II heterojunction CdIn2S4/BiVO4 is designed to improve the photocurrent density from 1.22 (pristine BiVO4) to 2.68 mA cm-2 at 1.23 V vs the reversible hydrogen electrode (RHE), accelerating the bulk separation of photogenerated carriers by the built-in field from the matched energy band. With the introduction of CQDs, CQDs/CdIn2S4/BiVO4 increases the photocurrent density to 4.84 mA cm-2, enhancing the light absorption and cathodically shifting its onset potential, due to the synergetic effect of the heterojunction and CQDs. Compared with BiVO4, CQDs/CdIn2S4/BiVO4 promotes the bulk separation efficiency to 94.6% and the surface injection efficiency to 72.2%. Additionally, spin-coating of FeOOH on CQDs/CdIn2S4/BiVO4 could further improve the PEC performance and keep a long stability for water splitting. The density function theory (DFT) calculations illustrated that the type-II heterojunction CdIn2S4/BiVO4 could decrease the oxygen evolution reaction (OER) overpotential and accelerate bulk charge separation for the built-in field of the aligned band structure.

18.
J Colloid Interface Sci ; 628(Pt B): 129-140, 2022 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-35987152

RESUMEN

Artificial photosynthesis has become one of the most attractive strategies for lowering atmospheric carbon dioxide (CO2) level and achieving the carbon balance; whereas, the fast electron-hole recombination and sluggish charge transfer in photocatalysts are themain stumbling blocks to the applications. Constructing semiconductor nano-heterostructures provides a promising strategy to accelerate the separation and transfer of photoinduced charge carriers for promoting the multielectron CO2 reduction reaction. Herein, a CdS/g-C3N4/α-Fe2O3 three-component photocatalyst consisting of type II and Z-scheme tandem heterojunctions is skillfully fabricated via the solvothermal synthesis followed with photoinduced deposition. The CdS/g-C3N4/α-Fe2O3 tandem-heterojunction photocatalyst exhibits superior performance toward the conversion of CO2 to fuels (CO and CH4), compared with the single- and binary-component systems, owing to the favorable energy-level alignment, accelerated charge separation, facilitated water dissociation and sufficient reactive-hydrogen provision. The total consumed electron number of CdS/g-C3N4/α-Fe2O3 catalyst for CO2 reduction is about 10.5 times that of pure g-C3N4. The photocatalytic mechanism is elucidated according to detailed characterizations and in-situ spectroscopy analyses. This work sheds light on the rational construction of heterojunction photocatalysts to promote the conversion of CO2 to solar fuels, without using any sacrifice reagent or noble-metal cocatalysts.

19.
J Colloid Interface Sci ; 627: 541-553, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-35870406

RESUMEN

Photocatalytic H2O2 production is an eco-friendly technique because only H2O, molecular O2 and light are involved. However, it still confronts the challenges of the unsatisfactory productivity of H2O2 and the dependence on organic electron donors or high purity O2, which restrict the practical application. Herein, we construct a type-II heterojunction of the protonated g-C3N4 coated Co9S8 semiconductor for photocatalytic H2O2 production. The ultrathin g-C3N4 uniformly spreads on the surface of the dispersed Co9S8 nanosheets by a two-step method of protonation and dip-coating, and exhibits improved photogenerated electrons transportability and e--h+ pairs separation ability. The photocatalytic system can achieve a considerable productivity of H2O2 to 2.17 mM for 5 h in alkaline medium in the absence of the organic electron donors and pure O2. The optimal photocatalyst also obtains the highest apparent quantum yield (AQY) of 18.10% under 450 nm of light irradiation, as well as a good reusability. The contribution of the type-II heterojunction is that the migrations of electrons and holes within the interface between g-C3N4 and Co9S8 matrix promote the separation of photocarriers, and another channel is also opened for H2O2 generation. The accumulated electrons in conduction band (CB) of Co9S8 contribute to the major channel of two-electron reduction of O2 for H2O2 production. Meanwhile, the electrons in CB of g-C3N4 participate in the single electron reduction of O2 as an auxiliary channel to enhance the H2O2 production.

20.
J Colloid Interface Sci ; 627: 438-448, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-35868039

RESUMEN

As a novel chalcogenide photocatalyst, MnPS3 suffered from limited visible light absorption, high photogenerated electron-hole recombination, and low hole oxidation capability due to its high valence band (VB) potential. In this work, the novel MnPS3 nanosheets-Nitrogen-doped carbon dots (NCDs) composites were fabricated by immobilizing NCDs with terminal amine groups on Na+ intercalated MnPS3 nanosheets for a greatly enhanced photocatalytic hydrogen production activity. MnPS3 nanosheets of 400 nm with Mn2+ vacancies are produced in high yield by NaCl intercalation and subsequent exfoliation in N-methylpyrrolidone (NMP). NCDs with 5 nm are evenly loaded on the surface of MnPS3 nanosheets of 400 nm via strong chemical interactions of ammonium sulfate salts formed at the interface. The MnPS3-NCDs composites exhibit enhanced light absorption at 500-600 nm, reduced charge recombination and notably promoted photocatalytic activity in relative to neat MnPS3 nanosheets. MnPS3-NCDs composite with the NCDs content of 16.5% possessed the highest photocatalytic hydrogen evolution rate of 339.63 µmol·g-1·h-1 with good cycling stability, which is 9.17 times that of exfoliated MnPS3 nanosheets. The type-II MnPS3-NCDs heterojunction is conducive to the efficient interfacial carrier transport and the significantly improved photocatalytic hydrogen generation activity. Our work confirmed that the non-toxic MnPS3 could possess photocatalytic performance comparable to CdS, which will be promising to become an attractive visible-light driven photocatalyst in environmental purification and energy applications.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA