应用于染料敏化太阳能电池的基于染料R6的含有不同吸电子基团的有机染料的理论研究

Dye-sensitized solar cells (DSSCs) are the most promising alternatives to traditional fossil energy because of their advantages of low production cost, facile structure, relatively low environmental impact, relatively high photoelectronic absorption efficiency, and overall high efficiency. In addition, several studies on sensitizers as vital components have been conducted over the last three decades. Compared to metal dyes, metal-free organic dyes have been considered as promising candidates because of their simple fabrication, multiple structures, high molar absorption coefficients, easily tunable properties, and environmental friendliness. In this study, we systematically investigated the optoelectronic properties of six metal-free organic donor-acceptor dyes (RD1–6) derived from the known dye R6 by using the density functional theory (DFT) and time-dependent DFT methods. Cell performance parameters were discussed, including the geometrical and electronic structures, absorption spectrum, adsorption energy, light harvesting efficiency (LHE) curve, predictive short circuit current density (J_sc^Pred.), predictive open circuit voltage (V_oc^Pred.), and theoretical power conversion efficiency (PCE). Results revealed that all the designed dyes exhibited high theoretical PCE. In particular, dyes RD1, 2, and 4–6 showed greater conjugations, and dyes RD1–3 had smaller energy gaps than those of the reference dye. In addition, dyes RD1–3, 5, and 6 exhibited better light harvesting capacities that covered the entire visible region and extended to the near-infrared region with obviously red-shift maximum absorption wavelengths (λ_max), wider LHE curves, and higher J_sc^Pred. as compared to the reference dye. It was critical that dyes RD1 and 2 not only have greater conjugations and narrow band gaps but also good light harvesting capacities with more than 56-nm red-shift maximum absorption wavelengths and broadened LHE curves than those of the reference dye. Notably, mainly because of an average increment of 12.0% of J_sc^Pred., a remarkable increment of the theoretical power conversion efficiency was observed from 12.6% for dye R6 to 14.1% for dyes RD1 and 2. Thus, dyes RD1 and 2 exhibited superior cell performances and could be promising sensitizer candidates for highly efficient DSSCs. These results could be used to guide effective synthetic efforts in the discovery of efficient metal-free organic dye sensitizers in DSSCs.     

Solar-Driven Artificial Carbon Cycle

Constituting the artificial carbon cycle,for example,through recycling CO₂ and converting CH₄ to value-added fuels and chemicals with solar energy,offers a sustainable future for humankind to tackle the global environmental issues and energy crisis.However,significant bottlenecks remain in such photocatalytic conversion,mainly related to the reaction activity and product selectivity.Herein,we share our efforts and systematic research progress on addressing the double bottlenecks for achieving solar-driven artificial carbon cycle,with specifically focusing on the photocatalytic CO₂ and CH₄ conversion.We further elucidate the common fundamentals behind various designed photocatalytic materials systems.Toward future development,we highlight the opportunities and challenges in the research field.     

Ni基乙烷脱氢催化剂的性能及其改进

过渡金属Ni是地球上储量丰富的金属元素, 在加氢脱硫、重整制氢等催化领域应用非常广泛, 但是关于Ni基催化剂在烷烃脱氢方面的研究较少; 因此, 本工作采用不同的方法, 制备了三种结构的Ni基负载催化剂, 即尖晶石分解型、浸渍型和钙钛矿析出型, 并在700 ℃、C₂H₆-N₂气氛中和50 mL•min^-1气体流速下, 探索了它们的乙烷脱氢性能. 结果表明: 尖晶石分解型催化剂Ni_1-xCu_xCr₂O₄还原后在Cr₂O₃表面形成Ni-Cu合金颗粒, 能有效钝化Ni的C—C键断裂活性, 提高乙烯的选择性. Ni含量过高时, Ni不能有效地分散而形成大的金属团簇, 造成乙烷过度裂解, 乙烯选择性较低. 浸渍负载型催化剂Ni_xM_y/Al₂O₃ (M为Cu或Ag) 比表面积大, 表面活性位点分散, 但活性金属与载体结合力弱, 在高温下不稳定; Cu或Ag与Ni形成合金, 可有效提高乙烯选择性, Ag较Cu的效果更佳. 钙钛矿析出型催化剂LaCr_1-xNi_xO₃(LCNi-100x)在还原气氛中析出均匀细小的Ni颗粒, 其与基体结合力强, 抗积碳性能和稳定性较高; 含15% Ni的LCNi-15还原后(R-LCNi-15)表现出最好的催化性能, 乙烯产率最高(24%), 同时具有较好的抗积碳性能和稳定性以及氧化再生性.     

太阳能光催化分解水制氢※

利用太阳能光催化分解水制氢是解决能源环境问题并实现太阳能有效转化和储存最有前途的技术之一, 这一“圣杯”式反应经过几十年不懈努力取得了诸多重要研究进展. 本文将综述光催化分解水制氢体系的基本概念、活性测试方法与注意事项、光催化材料种类等; 并从光催化分解水制氢的光吸收、光生电荷分离和表面催化反应等基本过程和关键科学问题的角度总结其重要研究进展, 最后对于太阳能光催化分解水制氢的挑战和潜在的发展方向进行分析和展望. 希望通过本综述的简要介绍能让刚从事光催化分解水制氢研究的青年科技人员清晰地了解掌握该领域的一些基本概念、操作规范、研究总体进展和现状等.     

A numerical Kramers-Kronig transform for the calculation of dielectric relaxation losses free from Ohmic conduction losses

 A numerical Kramers–Kronig transform is described which allows the calculation of dielectric relaxation losses from dielectric constant data measured at a limited set of frequencies differing by a factor of 2. Conversion formulas for both the central frequencies and for frequencies near the edges of the experimental frequency window are derived. The approach used can be extended easily to measurement frequencies with a different logarithmic spacing. Using this conversion, relaxation and dissipative, conduction losses can be separated. In this way Ohmic conduction processes and simultaneously occurring relaxation processes like dipole or space-charge relaxations can be analysed independently. The results of some simulations and of calculations on experimental data for poly(vinyl-chloride) are used to illustrate the potentials of the ɛ′ to ɛ″ conversion. Received: 17 May 1996 Accepted: 16 August 1996     

Conversion ofn-hexane over Pt?Sn/γ-Al2O3 catalyst

Conversion ofn-hexane has been applied as a test reaction to study differences between the series of Pt−Sn/γ-Al₂O₃ catalysts obtainedvia different methods of preparation. Preliminary results of catalytic experiments have been compared with some changes occurring on the catalysts surfaces as the results of the preparation technique applied. It has been found that catalysts with the second metal (Sn) introduced to the support by the coprecipitation technique were much more stable in comparison to the catalysts where the tin component has been added by the impregnation method, however, we have not observed large differences in catalytic activity.     

Understanding the Effect of Solvent Environment on the Interaction of Hydronium Ion with Biomass Derived Species: A Molecular Dynamics and Metadynamics Investigation

The addition of aprotic solvents results in higher reactivities and selectivities in many key aqueous phase biomass reactions, including the acid-catalyzed conversion of fructose to 5-hydroxyl methyl furfural (HMF). The addition of certain co-solvents inhibits the formation of humins via preferential solvation of key functional groups and can alter reaction kinetics. An important factor in this context is the relative stability of the hydronium ion (the catalyst) in the vicinity of the biomass moiety as compared to that in bulk, as it could determine its efficacy in the protonation step. Hence, in the present work, molecular dynamics (MD) simulations of HMF (the model product) and fructose (the model reactant) in acidic water and water-DMSO mixtures are performed to analyze their interaction with the hydronium ions. We show that the presence of DMSO favors the interaction of the hydronium ion with fructose, whereas it has a detrimental effect on the interaction of hydronium ion with HMF. Well-tempered metadynamics (WT-MTD) simulations are performed to determine the relative stability of the hydronium ion in the immediate vicinity of fructose and HMF, as compared to that in the bulk solvent phase, as a function of solvent composition. We find that DMSO improves the stabilization of the hydronium ions in the first solvation shell of fructose compared to that in the bulk solvent. On the other hand, hydronium ions become less stable in the immediate vicinity of HMF, as the concentration of DMSO increases.     

Bio-inspired and Eco-friendly Synthesis of 3D Spongy Meso-Microporous Carbons from CO2 for Supercapacitors

Inspired by the spongy bone structures, three-dimensional (3D) sponge-like carbons with meso-microporous structures are synthesized through one-step electro-reduction of CO₂ in molten carbonate Li₂CO₃−Na₂CO₃−K₂CO₃ at 580 °C. SPC4-0.5 (spongy porous carbon obtained by electrolysis of CO₂ at 4 A for 0.5 h) is synthesized with the current efficiency of 96.9 %. SPC4-0.5 possesses large electrolyte ion accessible surface area, excellent wettability and electronical conductivity, ensuring the fast and effective mass and charge transfer, which make it an advcanced supercapacitor electrode material. SPC4-0.5 exhibits a specific capacitance as high as 373.7 F g⁻¹ at 0.5 A g⁻¹, excellent cycling stability (retaining 95.9 % of the initial capacitance after 10000 cycles at 10 A g⁻¹), as well as high energy density. The applications of SPC4-0.5 in quasi-solid-state symmetric supercapacitor and all-solid-state flexible devices for energy storage and wearable piezoelectric sensor are investigated. Both devices show considerable capacitive performances. This work not only presents a controllable and facile synthetic route for the porous carbons but also provides a promising way for effective carbon reduction and green energy production.     

Multi-Channel Optical Device for Solar-Driven Bacterial Inactivation under Real-Time Temperature Feedback

Solar-driven photothermal antibacterial devices have attracted a lot of interest due to the fact that solar energy is one of the cleanest sources of energy in the world. However, conventional materials have a narrow absorbance band, resulting in deficient solar harvesting. In addition, lack of knowledge on temperature change in these devices during the photothermal process has also led to a waste of energy. Here, we presented an elegant multi-channel optical device with a multilayer structure to simultaneously address the above-mentioned issues in solar-driven antibacterial devices. In the photothermal channel, semiconductor IrO₂-nanoaggregates exhibited higher solar absorbance and photothermal conversion efficiency compared with nanoparticles. In the luminescence channel, thermal-sensitive Er-doped upconversion nanoparticles were utilized to reflect the microscale temperature in real-time. The bacteria were successfully inactivated during the photothermal effect under solar irradiation with temperature monitoring. This study could provide valuable insight for the development of smart photothermal devices for solar-driven photothermal bacterial inactivation in the future.     

SAPO-34分子筛骨架稳定性的研究

利用差热分析，原位ＸＲＤ技术，高温条件下的焙烧和水蒸气处理并关联其催化性能变化，研究了ＳＡＰＯ－３４分子筛的热及水热稳定性，差热分析结果表明，ＳＡＰＯ－３４的骨架破坏温度高于１３００Ｋ，原位ＸＲＤ跟踪研究证实，ＳＡＰＯ－３４分子筛原粉在高温焙烧以除掉有机胺及随后的降温过程中无明显的骨架破坏；而焙烧型ＳＡＰＯ－３４在空气中放置一定时间后，水分子吸附微孔中明业降低样品的ＸＲＤ峰强度，且降低幅度随放置时