- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Interfacial Charge Transfer in 0D/2D Defect-Rich Heterostructures for Efficient Solar-Driven CO2 Reduction
摘要： Two-dimensional graphitic carbon nitride (g-C3N4) has been widely explored as a promising photocatalyst for solar CO2 conversion. However, rapid charge recombination and low visible-light utilization are severely detrimental to photocatalytic CO2 conversion. Zero-dimensional/two-dimensional (0D/2D) heterostructures are considered the promising materials with size tunability and enhanced charge separation efficiency for photocatalysis. Herein, a 0D/2D heterostructure of oxygen vacancy-rich TiO2 quantum dots confined in g-C3N4 nanosheets (TiO2-x/g-C3N4) was prepared by in-situ pyrolysis of NH2-MIL-125 (Ti) and melamine. Charge dynamics analysis by time-resolved photoluminescence (tr-PL) and femtosecond and nanosecond pump-probed transient absorption (TA) spectra revealed that charges transfer occured from 2D-g-C3N4 to 0D-TiO2 at an ultrafast subpicosecond time scale (<1 ps) through the intimate interface. The overall fast decay of the charge carriers was attributed to interfacial charge transfer, which was accompanied by recombination relaxation mediated by shallow trapped sites. Ultrafast interfacial charge transfer greatly promoted charge separation as well as electrons in shallow trapped sites were easily trapped by CO2. In addition, combing with the synergetic advantage of strong visible light absorption, high CO2 adsorption and large surface area, TiO2-x/g-C3N4 exhibited a superior CO evolution rate of 77.8 μmol g?1 h?1, roughly 5 times that of pristine g-C3N4 (15.1 μmol g?1 h?1). This work provides in-depth insights into optimizing the heterojunction for robust solar CO2 conversion.
关键词： TiO2 quantum dots,solar CO2 reduction,charge transfer,0D/2D heterostructures,oxygen vacancy
更新于2025-09-23 15:22:29
-
3D Yolk@Shell TiO2-x/LDH Architecture: Tailored Structure for Visible Light CO2 Conversion
摘要： CO2 photo-conversion into hydrocarbon solar fuels by engineered semiconductors is considered as a feasible plan to address global energy requirements in times of global warming. In this regard, three dimensional yolk@shell hydrogenated TiO2/Co-Al layered double hydroxide (3D Y@S TiO2-x/LDH) architecture was successfully assembled by sequential solvothermal, hydrogen treatment and hydrothermal preparation steps. This architecture revealed a high efficiency for the photo-reduction of CO2 to solar fuels, without a noble metal co-catalyst. The time dependent experiment indicated that the production of CH3OH was almost selective until 2h (up to 251 μmol/gcat. h.), whereas the CH4 was produced gradually by increasing the time of reaction to 12h (up to 63 μmol/gcat. h.). This significant efficiency can be ascribed to the engineering of 3D Y@S TiO2-x/LDH architecture with considerable CO2 sorption ability in mesoporous yolk@shell structure, and LDH interlayer spaces. Also, oxygen vacancies in TiO2-x could provide excess sites for sorption, activation and conversion of CO2. Furthermore, the generated Ti3+ ions in the Y@S TiO2 structure as well as connecting of structure with LDH plates, can facilitate the charge separation and decrease the band gap of nanoarchitecture to the visible region.
关键词： Solar fuel,Oxygen vacancy,Photocatalysis,CO2 conversion,Nanoarchitectures
更新于2025-09-23 15:22:29
-
Density Functional Theory Calculations of Oxygen-Vacancy Formation and Subsequent Molecular Adsorption on Oxide Surfaces
摘要： The surface oxygen vacancy formation energy (EOvac) is an important parameter in determining the catalytic activity of metal oxides. Estimating these energies can therefore lead to data-driven design of promising catalyst candidates. In the present study, we determine EOvac for various insulating and semiconducting oxides. Statistical investigations indicate that the band gap, bulk formation energy, and electron affinity are factors that strongly influence EOvac. Electrons enter defect states after O desorption, and these states can be in the valence band, mid-gap, or in the conduction band. Subsequent adsorption of O2, NO, CO, CO2, and H2 molecules on an O-deficient surface is also investigated. These molecules become preferentially adsorbed at the defect sites, and EOvac is identified as the dominant factor that determines the adsorption mode as well as a descriptor that shows good correlation with the adsorption energy.
关键词： catalytic activity,molecular adsorption,oxygen vacancy formation energy,metal oxides,density functional theory
更新于2025-09-23 15:21:21
-
Magnetic and optical behaviors of SnO2-x thin films with oxygen vacancies prepared by atomic layer deposition
摘要： SnO2-x thin films with different concentration oxygen vacancies were prepared by Atomic Layer Deposition (ALD). Specifically, the oxygen vacancy concentration was controlled by the oxidation pulse time during the ALD process. The crystal structure of the as-prepared thin films was determined by XRD, and the magnetic properties were measured by VSM, while the optical properties were measured by optical transmittance spectrum. The results showed that the oxygen vacancy concentration of the SnO2-x could be controlled by the oxidation pulse time, and the crystal structures, magnetic properties, and optical properties were largely impacted by the concentration of oxygen vacancy.
关键词： microstructure,thin film,magnetic,diffraction,nanocrystal,oxygen vacancy
更新于2025-09-23 15:21:21
-
Effect of oxygen vacancy on structural, optical, and photocatalytic properties of ceria films grown by magnetron sputtering deposition
摘要： Cerium oxide is of crucial importance for intrinsic redox reaction, which is attributed to the active sites neighboring oxygen vacancies. However, the role of oxygen vacancy (Ov) on the various properties of ceria ?lms remains to be elucidated. Herein, ceria ?lms were deposited by magnetron sputtering and the e?ect of electric current intensity on the creation of Ov was systematically investigated. X-ray photoelectron spectroscopy (XPS) results show that the Ce4+ concentration decreases with the increase of current intensity, which demonstrates that Ov can be created and tuned during ?lm deposition by controlling electric current intensity. The ?lm fabricated by 6 A current intensity has 42% Ce4+, approaching that of rhombohedral-Ce7O12, which is a stabilized bulk phase ceria. X-ray di?raction patterns reveal that 6 A ?lm shows mixed crystalline phases with the majority of peaks very close to rhombohedral-Ce7O12, while 1 A, 2 A, and 4 A ceria ?lms show simple crystalline phase. Raman analysis presents that dioxygen species are heavily absorbed on the surface of 6 A ?lm with more active sites on di?erent crystalline surfaces, which is con?rmed by photocatalytic degradation of Methylene Blue. The calculated bandgap by DFT (density functional theory) + U is consistent with that obtained from Tauc plots curves. This work demonstrates that Ov plays an important role on the properties of the ceria ?lm.
关键词： XPS,Raman,Oxygen vacancy,Magnetron sputtering,Cerium oxide
更新于2025-09-23 15:21:01
-
Ferromagnetic Properties of N-Doped and Undoped TiO2 Rutile Single-Crystal Wafers with Addition of Tungsten Trioxide
摘要： In this work, undoped, N-doped, WO3-loaded undoped, and WO3-loaded with N-doped TiO2 rutile single-crystal wafers were fabricated by direct current (DC) magnetron sputtering. N-doping into TiO2 and WO3 loading onto TiO2 surface were used to increase and decrease oxygen vacancies. Various measurements were conducted to analyze the structural and magnetic properties of the samples. X-ray diffraction results showed that the N-doping and WO3 loading did not change the phase of all samples. X-ray photoelectron spectroscopy results revealed that W element loaded onto rutile single-crystal wafers existed in the form of WO3. UV-Vis spectrometer results showed that the absorption edge of WO3-loaded undoped and WO3-loaded with N-doped TiO2 rutile single-crystal wafers had red shift, resulting in a slight decrease in the corresponding band gap. Photoluminescence spectra indicated that oxygen vacancies existed in all samples due to the postannealing atmosphere, and oxygen vacancies density increased with N-doping, while decreasing with WO3 loading onto TiO2 surface. The magnetic properties of the samples were investigated, and the saturation magnetization values were in the order N-doped > WO3-loaded with N-doped > undoped > WO3-loaded undoped rutile single-crystal wafers, which was the same order as the oxygen vacancy densities of these samples. N-doping improved the saturation magnetization values, while WO3-loaded decreased the saturation magnetization values. This paper reveals that the magnetic properties of WO3-loaded with N-doped rutile single-crystal wafers originate from oxygen vacancies.
关键词： rutile TiO2 single-crystal wafers,WO3-loaded,oxygen vacancy,ferromagnetic properties
更新于2025-09-23 15:21:01
-
Influence of Oxygen Vacancy Behaviors in Cooling Process on Semiconductor Gas Sensors: A Numerical Analysis
摘要： The in?uence of oxygen vacancy behaviors during a cooling process in semiconductor gas sensors is discussed by the numerical analysis method based on the gradient-distributed oxygen vacancy model. A diffusion equation is established to describe the behaviors of oxygen vacancies, which follows the effects of diffusion and exclusion in the cooling process. Numerical analysis is introduced to ?nd the accurate solutions of the diffusion equation. The solutions illustrate the oxygen vacancy distribution pro?les, which are dependent on the cooling rate as well as the temperature interval of the cooling process. The gas-sensing characteristics of reduced resistance and response are calculated. Both of them, together with oxygen vacancy distribution, show the grain size effects and the re-annealing effect. It is found that the properties of gas sensors can be controlled or adjusted by the designed cooling process. The proposed model provides a possibility for sensor characteristics simulations, which may be bene?cial for the design of gas sensors. A quantitative interpretation on the gas-sensing mechanism of semiconductors has been contributed.
关键词： numerical analysis,oxygen vacancy,gas sensor,semiconductor,diffusion equation
更新于2025-09-23 15:21:01
-
Embedding of WO3 nanocrystals with rich oxygen-vacancies in solution processed perovskite film for improved photovoltaic performance
摘要： Seeking strategies of promoting the charge separation and transport of the photo-active layer has been always of significance for the development of high-performance optoelectronic devices. We herein demonstrate an effective way of decorating WO3 nanocrystals in perovskite films for boosted photogenerated carriers transport. The WO3 nanocrystals are generated by a simple technique of pulsed laser irradiation in liquid, then introduced into the perovskite film based on the anti-solvent approach. Such decoration is found helpful for the increase of the short-circuit current density (Jsc) of the device, which leads to the increase of the photoconversion efficiency (PCE) from 17.72% to 19.29%. The improved PCE is mainly due to the decoration of the WO3 at the grain boundaries of perovskite films that facilitates the charge transport between the adjacent grains, which is evidenced by the quenching of the film photoluminescence, shortened carrier lifetime, and increased carrier mobility. We thus believe our study provides an effective way of embedding ordinary metal oxides in perovskite films for enhanced optoelectronic performance.
关键词： Hybrid perovskite solar cell,Pulsed laser irradiation in liquid,WO3 nanocrystals,Charge transport,Oxygen-vacancy
更新于2025-09-23 15:19:57
-
Visible Light CO2 Reduction to CH4 Using Hierarchical Yolk@shell TiO2-xHx Modified with Plasmonic Au-Pd Nanoparticles
摘要： Engineering of advanced semiconductor photocatalysts for CO2 conversion to solar fuels is a promising strategy to solve the greenhouse effect and energy crisis. Herein, hierarchical urchin-like yolk@shell TiO2-xHx decorated with core/shell Au-Pd plasmonic nanoparticles (HUY@S-TOH/AuPd) have been prepared using a multi-step process and employed as advanced visible light active photocatalyst in CO2 conversion to CH4 with rate of 47 μmol/gcat.h (up to 126 μmol/gcat after 7h). Different engineered sites in this structure for high gas adsorption, powerful visible light activation and intense electron transportation are responsible for the observed high photocatalytic CO2 conversion efficiency. The present smart designing process can produce a considerable cooperation, not only to disclose the architectural engineering to improvement of photo-conversion efficiency, but also as a viable and appropriate photocatalytic process to sustainable energy production.
关键词： nanoarchitecture,Plasmonic nanoparticles,Photocatalysis,CO2 Conversion,Oxygen vacancy
更新于2025-09-23 15:19:57
-
Oxygen Vacancies Enabled Porous SnO <sub/>2</sub> Thin Films for Highly Sensitive Detection of Triethylamine at Room Temperature
摘要： Detection of volatile organic compounds (VOCs) at room temperature (RT) currently remains a challenge for metal oxide semiconductor (MOS) gas sensors. Herein, we for the first time report on the utilization of porous SnO2 thin films for RT detection of VOCs by defect engineering of oxygen vacancies. The oxygen vacancies in the three-dimensional ordered SnO2 thin films, prepared by a colloidal template method, can be readily manipulated by thermal annealing at different temperatures. It is found that oxygen vacancies play an important role in the RT sensing performances, which successfully enables the sensor to respond to triethylamine (TEA) with an ultrahigh response, e.g. 150.5 to 10 ppm TEA in a highly selective manner. In addition, the sensor based on oxygen vacancy-rich SnO2 thin films delivers a fast response and recovery speed (53 and 120 s), which can be further shortened to 10 and 36 s by elevating the working temperature to 120 oC. Notably, a low detection limit of 110 ppb has been obtained under RT. The overall performances surpass most previous reports on TEA detection at RT. The outstanding sensing properties can be attributed to the porous structure with abundant oxygen vacancies, which can improve the adsorption of molecules. The oxygen vacancy engineering strategy and the on-chip fabrication of porous MOS thin film sensing layers deliver a great potential for create high-performance RT sensors.
关键词： Oxygen vacancy,Porous film,Gas sensor,Tin dioxide,Room temperature
更新于2025-09-23 15:19:57