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Molecule-Driven Shape Control of Metal Co-Catalysts for Selective CO? Conversion Photocatalysis
摘要： In photocatalysis of CO2 conversion, metal co-catalysts draw photo-generated electrons from semiconductor components and act as reaction sites by adsorbing CO2 and its intermediates. Optimization of the metal co-catalyst structure is indispensable to improving the efficiency of the photocatalyst, which is currently not meeting performance requirements. By performing a series of experiments and simulations, we demonstrate the effect of selective particle shape control of metal co-catalysts (Au, Ag, Cu and Pt) by the CO2 induced gas ligands (CO2 and CO) on photocatalytic CO2 conversion activity and selectivity. Indeed, facet formation for adsorption of CO2 and CO proves to be an effective way to improve the CO2 conversion activity. In particular, proper interaction between the gas ligand and the metal co-catalyst surface, realized by strengthening the metal-CO2 adsorption and weakening the metal-CO adsorption, is identified as essential factor for increasing the CO2 conversion activity. Pt and Cu, which exhibit relatively strong interaction with gas molecules, have the improved photocatalytic CO2 conversion activity when grown under CO2. In contrast, Au and Ag, which exhibit relatively weak interaction with gas molecules, have the enhanced photocatalytic CO2 conversion activity when grown under CO. This systematic understanding can be a guideline for controlling the metal co-catalyst surface structure and will maximize the photocatalytic selectivity of the CO2 conversion.
关键词： CO2 reduction,Activity and selectivity,Transition metal co-catalyst,Facet control,Photocatalyst
更新于2025-09-10 09:29:36
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Function-integrated Ru catalyst for photochemical CO2 reduction
摘要： Visible-light driven catalytic reduction of CO2 is at the heart of artificial photosynthesis. Here, we demonstrate the first example of a Ru complex that can function both as a photosensitizer and catalyst for CO2 reduction. The catalyst exhibited excellent activity for CO evolution with a high turnover number (TON, 353 for 24 h), reaction rate (TOF, 14.7 h?1), and product selectivity (97%) under visible-light irradiation. We also succeeded in selective product formation (CO or HCOOH) by changing the basicity of the reaction media. This finding will open new avenues for visible-light driven photoredox catalysis using Ru-based function-integrated photocatalysts.
关键词： Ru complex,visible-light,artificial photosynthesis,CO2 reduction,photocatalysis
更新于2025-09-10 09:29:36
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Nanoscale Kirkendall effect driven Au Decorated CdS/CdO Colloidal Nanocomposites for Efficient Hydrogen Evolution, Photocatalytic Dye Degradation and Cr (VI) Reduction
摘要： The design of a facile and scalable method to synthesize solar light driven photocatalyst to generate H2 from water and degradation of toxic dyes from waste water is highly challenging field of research. Here, we are reporting a one pot synthesis of CdS/CdO colloidal nanocomposite with variable amount of CdS thickness and finally CdS nanoring. Different outward diffusion rate of oxygen and inward diffusion rate of sulphur ions generates hollow CdS/CdO nanocomposite based on nanoscale Kirkendall effect. Au nanoparticles (NPs) have been selectively deposited over CdS. Proper band alignment among CdO, CdS and Au results in a Z-type photocatalyst. Efficient spatial charge separation and large surface area lead to high photocatalytic dye degradation and Cr (VI) reduction in water. The amount of Cd in purified water is lesser than 0.003 ppm which maintains world Health Organization (WHO) guideline. The as developed catalyst is also active for generation of H2 from water in presence of solar light irradiation. Our present work may provide a promising way to fabricate an efficient photocatalyst for dye degradation and solar to fuel energy conversion using semiconductor (CdO)-semiconductor (CdS)-metal (Au) nanocomposite.
关键词： Dye Degradation,Hollow Nanocomposite,Kirkendall Effect,Z-scheme,H2 Production,Cr (VI) Reduction
更新于2025-09-10 09:29:36
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Large-scale synthesis of size-controllable Ag nanoparticles by reducing silver halide colloids with different sizes
摘要： In present study, double-jet precipitation method was employed to prepare the uniform AgX (X: Cl, Br, I) colloids, and then ascorbic acid/sodium borohydride was respectively used to reduce AgX into the silver nanoparticles (Ag NPs). The main experimental parameters about above two processes were investigated. It was found that under the same synthesis conditions the size of obtained Ag NPS was strongly dependent on the AgX size，and the silver particles obtained by reduction of AgCl, AgBr and AgI had the monotonously diminishing size order. SEM, TEM, XRD, and UV spectrometry were employed to characterize the obtained AgX and Ag NPs respectively, and they gave the size variation clearly and the mechanism was discussed.
关键词： Silver halide,Controllable,Double-jet precipitation,Reduction,Ag nanoparticles
更新于2025-09-10 09:29:36
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Two-step Synthesis of Laminar Vanadate via a Facile Hydrothermal Route and Enhancing the Photocatalytic Reduction of CO2 into Solar Fuel through Tuning the Oxygen Vacancies by in situ Vacuum Illumination Treatment
摘要： Monoclinic LaVO4, tetragonal CeVO4 and monoclinic Pb2V2O7 with laminar structures composed of nanosheets have been successfully fabricated using a two-step facile hydrothermal route. The narrow-bandgap LaVO4, CeVO4 and Pb2V2O7 vanadate exhibited photocatalytic activity towards the photoreduction of CO2 into C2H5OH in the liquid phase. The existence of oxygen vacancies on LaVO4 surface further enhanced the photocatalytic activity for photoreduction of CO2 into CO in gas phase, which can be easily obtained using a vacuum illumination treatment. The EPR, PL and FTIR results indicated that oxygen vacancies are beneficial to the separation of electrons by prolonging the lifetime of the photogenerated electrons and enhancing the chemisorption of CO2 on the photocatalyst surface.
关键词： Laminar structure,Photocatalytic reduction of CO2,Vanadate,Oxygen vacancy,Photocatalytic activity
更新于2025-09-10 09:29:36
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In situ Raman spectroscopic evidence for oxygen reduction reaction intermediates at platinum single-crystal surfaces
摘要： Developing an understanding of structure–activity relationships and reaction mechanisms of catalytic processes is critical to the successful design of highly efficient catalysts. As a fundamental reaction in fuel cells, elucidation of the oxygen reduction reaction (ORR) mechanism at Pt(hkl) surfaces has remained a significant challenge for researchers. Here, we employ in situ electrochemical surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) calculation techniques to examine the ORR process at Pt(hkl) surfaces. Direct spectroscopic evidence for ORR intermediates indicates that, under acidic conditions, the pathway of ORR at Pt(111) occurs through the formation of HO2*, whereas at Pt(110) and Pt(100) it occurs via the generation of OH*. However, we propose that the pathway of the ORR under alkaline conditions at Pt(hkl) surfaces mainly occurs through the formation of O2?. Notably, these results demonstrate that the SERS technique offers an effective and reliable way for real-time investigation of catalytic processes at atomically flat surfaces not normally amenable to study with Raman spectroscopy.
关键词： density functional theory,in situ Raman spectroscopy,electrochemical surface-enhanced Raman spectroscopy,oxygen reduction reaction,platinum single-crystal surfaces
更新于2025-09-10 09:29:36
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Fast method for analysing nonlinear composite right/left-handed transmission lines based on finite-difference time-domain method
摘要： In this study, a new finite-difference time-domain (FDTD) scheme is presented for analysing nonlinear composite right/left-handed (CRLH) transmission lines, with reduction of the central processing unit time. A step by step analysis is demonstrated to solve the equations for nonlinear CRLH transmission lines based on the FDTD method. The proposed method is applied to a nonlinear CRLH transmission line as an example and the results are confirmed by those of the conventional FDTD method. The comparisons reveal that the presented solution efficiently decreases by about 82% of the computational time consumption.
关键词： finite-difference time-domain (FDTD),computational time reduction,nonlinear composite right/left-handed (CRLH) transmission lines
更新于2025-09-10 09:29:36
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Insight into Reinforced Photocatalytic Activity of CNT-TiO <sub/>2</sub> nanocomposite for CO <sub/>2</sub> Reduction and Water Splitting
摘要： Using titanium dioxide (TiO2) and its modified forms for photocatalytic reduction of CO2 reduction and production of hydrogen are promising routes for providing solutions to the world energy demand in the foreseeable future. Here, we report the synthesis of a series of efficient, stable TiO2 nanoparticles modified with multi-walled carbon nanotubes (CNT) via a simple, combined sonothermal method followed by a hydrothermal treatment. In comparison to bare TiO2, the synthesized CNT-TiO2 photocatalysts showed improved photocatalytic activities for CO2 reduction under UVA as well as under visible light; and water (H2O) splitting under visible light at ambient temperature and pressure. The 2.0CNT-TiO2 has performed the best for methanol, hydrogen and formic acid production from the reduction of CO2 with yield rates of 2360.0, 3246.1 and 68.5 μmol g-1 h-1 under UVA, respectively. Its potential was further tested under visible light for methanol production, 1520.0 μmol g-1 h-1. Also, the highest rate of hydrogen yield from water splitting was 69.41 μmol g-1 h-1 with 2.0CNT-TiO2 under visible light at pH 2. The primary photocatalytic reactions of CNT-TiO2 composites and their intimate structure were studied computationally. It was demonstrated that the binding of CNT to TiO2 nanoparticles are preferable at (101) surfaces compared to (001) facets. Interaction of CNT with TiO2 results in common orbitals within TiO2 band gap that enables visible light excitation of the CNT-TiO2 composites can lead to charge transfer between TiO2 and CNT; while UV light excitation can result in charge transfer in any direction, from CNT to TiO2 and from TiO2 to CNT. The latter process is operative in the presence of sacrificial electron donor TEOA.
关键词： photocatalytic reduction,CO2 reduction,UVA light,water splitting,visible light,CNT-TiO2 nanocomposite,hydrogen production
更新于2025-09-09 09:28:46
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - PolSAR Image Classification Based on DBN and Tensor Dimensionality Reduction
摘要： This paper proposes a new semi-supervised PolSAR image classification method using deep belief network (DBN) and tensor dimensionality reduction, which uses multilinear principle component analysis (MPCA) to reduce the dimension of tensor form PolSAR data, and regards the multiple features of PolSAR data as the input of DBN. In order to take full advantage of neighborhood information of each pixel of PolSAR data, we take each pixel and its neighborhood as tensor form. For PolSAR data, simple feature has been proven not to be able to effectively classify complex terrains. Therefore, we combine multiple features of PolSAR data to obtain more abundant information, which can reflect some spatial structure of PolSAR data. The experimental results show that the overall classification accuracy based on the proposed method outperforms the traditional classification strategies.
关键词： deep belief network,image classification,PolSAR,tensor dimensionality reduction
更新于2025-09-09 09:28:46
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Co-production of syngas and zinc via combined solar-driven biomass gasification and ZnO carbo-thermal reduction in a continuously-operated solar reactor
摘要： The solar thermochemical gasification of biomass with in-situ ZnO carbo-thermal reduction was carried out in a lab-scale (1.5 kW) continuously-fed solar reactor. The objective of this study was to demonstrate the feasibility of the combined process involving wood biomass gasification with ZnO as an oxidizing agent under continuous process operation for co-production of syngas and metallic Zn. A controlled mixture of biomass and ZnO particles was injected in a cavity-type receiver directly irradiated by concentrated solar radiation. The influence of temperature (1050-1250°C) on syngas production was experimentally investigated and compared to the case of a pyrolysis process (without any oxidizing agent). H2 production increased drastically, CO production tended also to increase, while CH4 and CO2 concentrations decreased when increasing the temperature. The global syngas production of the combined gasification and ZnO carbo-thermal reduction was higher in comparison with pyrolysis. Collected products at the reactor outlet indicated high Zn content, with low recombination to ZnO in the solid products. The energy content of the feedstock was upgraded by the solar power input in the form of both syngas and Zn, thus outperforming pyrolysis in addition to delivering higher syngas output per unit of feedstock.
关键词： ZnO carbo-thermal reduction,syngas,biomass,metallic Zn,solar thermochemical gasification
更新于2025-09-09 09:28:46