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Fabrication of MoS2/TiO2 heterostructure with enhanced photocatalytic activity
摘要： Two dimensional nanophotocatalysts MoS2/TiO2 with tunable decoration amount of MoS2 nanosheets were fabricated through hydrothermal route. The microstructure and photocatalytic behavior of as?prepared samples were characterized by X?ray diffraction, scanning electron microscope, transmission electron microscopy, UV?vis diffuse reflectance spectra, electrochemical workstation, dye degradation and water splitting experiment. The result shows that these composites exhibited enhanced photocatalytic activity for RhB degradation and hydrogen generation. Nearly 95% photocatalytic degradation of RhB was obtained for 2 h and 1.93 mmol g?1 h?1 of hydrogen production rate was achieved over MoS2/TiO2 at a MoS2 content of 10 wt%. And the corresponding photocurrent density of composite photoelectrode was 5?fold higher than that of pristine TiO2 architectures. It is believed that the boosting photocatalytic performance of heterostructure could be ascribed to the synergetic effect between the MoS2 and TiO2, which accelerated the separation and migration efficiency of charge carries as well as enhanced the light?harvest efficiency.
关键词： photocatalytic activity,photogenerated electron?hole pairs,heterostructure,photocatalyst,MoS2/TiO2
更新于2025-11-14 15:13:28
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Model To Determine a Distinct Rate Constant for Carrier Multiplication from Experiments
摘要： Carrier multiplication (CM) is the process in which multiple electron?hole pairs are created upon absorption of a single photon in a semiconductor. CM by an initially hot charge carrier occurs in competition with cooling by phonon emission, with the respective rates determining the CM e?ciency. Up until now, CM rates have only been calculated theoretically. We show for the ?rst time how to extract a distinct CM rate constant from experimental data of the relaxation time of hot charge carriers and the yield of CM. We illustrate this method for PbSe quantum dots. Additionally, we provide a simpli?ed method using an estimated energy loss rate to estimate the CM rate constant just above the onset of CM, when detailed experimental data of the relaxation time is missing.
关键词： carrier multiplication,quantum yield,quantum dots,semiconductor,electron?hole pairs
更新于2025-09-23 15:22:29
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Enhancing the Output Performance of Triboelectric Nanogenerator via Grating‐Electrode‐Enabled Surface Plasmon Excitation
摘要： The surface charge density and the output impedance of triboelectric nanogenerators (TENGs) are two critical factors for TENGs to speed up their commercialization, so it is important to explore unique methods to reduce the output impedance and increase the surface charge density. Here, an approach is demonstrated to effectively boost the output performance of TENG while reducing the output impedance of TENGs by utilizing grating-electrode-enabled surface plasmon excitation. A sustainable and enhanced output performance of about 40 μA (short-circuit current) and 350 V (peak-to-peak voltage at a resistance of 10 MΩ) is produced via grating-coupled surface plasmon resonance on the TENG with the aluminum grating electrode in the line density of 600 lines mm?1, and it delivers a peak output power of 3.6 mW under a loading resistance of 1 MΩ, giving over 4.5-fold enhancement in output power and a 75% reduction in the output impedance. Finally a self-powered ultrasonic ranging system is utilized to verify the capability of the TENG in powering portable electrics.
关键词： optical grating,surface plasmon resonance,hot electron–hole pairs,triboelectric nanogenerators
更新于2025-09-19 17:13:59
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Physics of Energy Conversion () || 10. Photovoltaic energy conversion
摘要： In a photovoltaic device, solar energy is converted into electricity along a path very different from the one taken in a solarthermal power plant. Here, in a first step the energy of the solar photons is converted into chemical energy in a solid state absorber. This means that the absorber is brought into an electronically excited state involving a reconfiguration of its charge carriers by the generation of electron/hole (e?/h+)-pairs, i.e. by the following reaction: Ground state + ?? → e? + h+. Here, ?? represents a photon with sufficient energy to bring an electron to the excited state. The chemical energy of the charge carrier ensembles in the conduction and valence bands is then converted into electrical energy by spatially separating the e?/h+-pairs via electrical contacts of the absorber which are electron or hole selective, respectively. In general such selective contacts can only be realized by a jump in the material properties between the two contacts, an example for this being a pn-junction. Since under illumination electrons and holes have different electrochemical potentials in the absorber material, this separation leads to a voltage drop between the contacts selective for the different charge carrier types. It is thus the selectivity of the contacts that introduces the built-in asymmetry into the solar cell, making it a usable voltage source (see Section 5.2). This basic working principle is true for all types of solar cells, ranging from conventional solar cells built from crystalline silicon (c-Si) over thin film solar cells fabricated from different materials such as, e.g. Cu(In,Ga)Se2 (CIGS) to organic or dye sensitized solar cells, and is schematically shown in Figure 10.1.
关键词： electricity,solid state absorber,solar energy,photovoltaic,pn-junction,dye sensitized solar cells,organic solar cells,CIGS,thin film solar cells,crystalline silicon,electron/hole pairs
更新于2025-09-11 14:15:04
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Microstructure and photocatalytic performance of BiVO4 prepared by hydrothermal method
摘要： Monoclinic BiVO4 photocatalyst was hydrothermally synthesized at different pH conditions without surfactant. The microstructure and photocatalytic behavior of as?prepared samples were characterized by X?ray diffraction, scanning electron microscope, transmission electron microscopy, UV?vis diffuse reflectance spectra, electrochemical workstation and dye degradation experiment. The results show that the pH value had a significant influence on the microstructure and photocatalytic performance of BiVO4. In acid environment, heavy precipitation of tetragonal BiVO4 took place in a short time at room temperature, whereas only amorphous powders formed as the pH value was equal or higher than 7. The monoclinic BiVO4 gradually nucleated and grew at the early stage of synthesis procedure at 180°C, and finally became the unique crystalline phase. The relationship between microstructure and photocatalytic activity the photocatalyst was well discussed. It is observed that the BiVO4 prepared in the neutral condition (pH 7) exhibited desirable photocatalytic degradation efficiency toward Rhodamine B solution, mainly due to the efficient separation of photogenerated electron?hole pairs and enhanced visual light absorption during degradation process, which were ascribed to the comprehensive function of high exposed {010} crystal facets, close packed structure, small particle size, and special floating characteristic.
关键词： BiVO4,microstructure,photogenerated electron?hole pairs,photocatalyst,photocatalytic activity
更新于2025-09-09 09:28:46
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Cascade electronic band structured zinc oxide/ bismuth vanadate/ three-dimensional ordered macroporous titanium dioxide ternary nanocomposites for enhanced visible light photocatalysis
摘要： Ternary zinc oxide/ bismuth vanadate/ three-dimensional ordered macroporous titanium dioxide (ZnO/BiVO4/3DOM TiO2) heterojuncted nanocomposites with cascade electronic band structures were successfully designed and synthesized for visible light photodegradation of two different molecules: Rhodamine B (RhB) and Tartrazine. The photocatalytic active species have been investigated by using electron scavenger (AgNO3) and hole scavenger (Triethanolamine: TEOA). The band edge positions of each component in tenary nanocomposites have been measured by using photoelectrochemical Mott-Schottky method and valence band XPS (VB-XPS) spectroscopy. Within the heterojunction, charges are favorably and spatially separated through the gradient potential at the interfaces. This largely suppresses the recombination of photogenerated electrons and holes. Furthermore, 3DOM inverse opal structure is beneficial for high diffusion efficiency and highly accessible surface area of reactants and light and multiple scattering for light harvesting. Consequently, these heterojuncted nanocomposites exhibit highly enhanced photocatalytic performance compared with pure BiVO4 nanostructure, and binary BiVO4/3DOM TiO2, ZnO/BiVO4 nanocomposites. A detailed mechanism of charge transfer is proposed for these ternary ZnO/BiVO4/3DOM TiO2 nanocomposites on the basis of a large series of spectroscopic and photocatalytic results. Our work demonstrates clearly that coupling multicomponent semiconductors with different energy levels of conduction and valence bands can significantly increase the photogenerated charge carriers through the efficient charge separation across their multiple interfaces. This work gives some new ideas on developing new visible light responsive nanocomposites for highly efficient solar energy utilization.
关键词： visible light,RhB and Tartrazine,Ternary ZnO/BiVO4/3DOM TiO2 nanocomposites,photogenerated electron–hole pairs,heterojunction structures
更新于2025-09-04 15:30:14