Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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Hansen Solubility Parameters of Coal Tar-Derived Typical PAHs Using Turbidimetric Titration and an Extended Hansen Approach
No full textThe advantage of selectivity for coal tar extraction can be obtained by using the solubility parameter of Hansen theory as a guide. However, most of the Hansen solubility parameters (dispersion contributions, (delta)(d); polarity contributions, (delta)(p); hydrogen bonding contributions, (delta)(hb)) of coal tar components (e.g., polycyclic aromatic hydrocarbons, PAHs) were inadequate. This study estimated the Hansen solubility parameters of naphthalene, acenaphthene, anthracene, phenanthrene, pyrene, and fluoranthene from coal tar by applying a new approach regulated by turbidimetric titration and a calculating program based on the method of exhaustion. The extended Hansen approach was used to verify the new approach and evaluate the solubility of the six PAH components in different solvents. The results show that the new method can clearly identify the differences in Hansen solubility parameters caused by various combinations of benzene rings among some isomers (e.g., anthracene and phenanthrene). Among the six PAH compounds, high relativity between their Hansen solubility parameters and solubility data was revealed, indicating an excellent reliability of the new method. An extended Hansen approach is appropriate for the estimation of solubility for the six PAHs with acceptable deviations. Moreover, the relationship between the Hansen solubility sphere and the extended Hansen approach was successfully presented by regression analysis
Efficient whole-cell-catalyzing cellulose saccharification using engineered Clostridium thermocellum
No full textBackground: Cost-efficient saccharification is one of the main bottlenecks for industrial lignocellulose conversion. Clostridium thermocellum naturally degrades lignocellulose efficiently using the cellulosome, a multiprotein supermolecular complex, and thus can be potentially used as a low-cost catalyst for lignocellulose saccharification. The industrial use of C. thermocellum is restrained due largely to the inhibition of the hydrolysate cellobiose to its cellulosome. Although the supplementation of beta-glucosidase may solve the problem, the production of the enzymes greatly complicates the process and may also increase the cost of saccharification
Li4Ti5O12-based energy conversion and storage systems: Status and prospects
No full textThe "zero-strain" spinel lithium titanate oxide (Li4Ti5O12) has been extensively studied as one of the most promising alternatives to carbon materials in energy conversion and storage devices, because of its negligible volume change (only 0.2-0.3%), ultrahigh rate capability, excellent safety characteristics (suppressed formation of solid-electrolyte interphase (SEI) layer and avoided growth of lithium dendrites) and cycling stability (intrinsic zero strain). However, the commercial large-scale applications of LTO-based Li-ion batteries (LIBs) and Li-ion capacitors (LICs) are greatly limited presently. This review mainly concentrates on full cells of LTO-based LIBs and LICs from basic research to applied research. As for various types of LTO-based LIBs, issues on material-cell performance relationships, compatibility of electrolytes, specific applications, overall cost analysis, safety evaluations, gassing mechanisms/remedies, and flexible/micro cell designs, are elaborated. This review also makes a concise summary of the evolution of electrochemical capacitors (ECs), and an exhaustive description of various types of LTO-based LICs on issues of new electrode materials, electrolyte optimization, and cell balancing. Finally, some helpful perspectives are provided to promote the future development of LTO-based LIBs and LICs with high performances. (C) 2017 Elsevier B.V. All rights reserved
Regulating Molecular Aggregations of Polymers via Ternary Copolymerization Strategy for Efficient Solar Cells
No full textFor many high-performance photovoltaic materials in polymer solar cells (PSCs), the active layers usually need to be spin-coated at high temperature due to the strong intermolecular aggregation of donor polymers, which is unfavorable in device repeatability and large-scale PSC printing. In this work, we adopted a ternary copolymerization strategy to regulate polymer solubility and molecular aggregation. A series of D-A(1)-D-A(2) random polymers based on different acceptors, strong electron-withdrawing unit ester substituted thieno[3,4-b]thiophene (TT-E), and highly planar dithiazole linked TT-E (DTzTT) were constructed to realize the regulation of molecular aggregation and simplification of device fabrication. The results showed that as the relative proportion of TT-E segment in the backbone increased, the absorption evidently red-shifted with a gradually decreased aggregation in solution, eventually leading to the active layers that can be fabricated at low temperature. Furthermore, due to the excellent phase separation and low recombination, the optimized solar cells based on the terpolymer P1 containing 30% of TT-E segment exhibit high power conversion efficiency (PCE) of 9.09% with a significantly enhanced fill factor up to 72.86%. Encouragingly, the photovoltaic performance is insensitive to the fabrication temperature of the active layer, and it still could maintain high PCE of 8.82%, even at room temperature. This work not only develops the highly efficient photovoltaic materials for low temperature processed PSCs through ternary copolymerization strategy but also preliminarily constructs the relationship between aggregation and photovoltaic performance
Properties of Nanocelluloses and Their Application as Rheology Modifier in Paper Coating
No full textIn this study, different nanocellulose (NC) products were manufactured from corncob residue (CCR) through sulfuric acid hydrolysis, formic acid hydrolysis, and TEMPO-mediated oxidation methods (the products were referred as SCN, FCN, and TCN, respectively). The properties of NC products and their impact on rheological behavior of paper coatings were comparatively studied. Results showed that compared to SCN and TCN, FCN exhibited large dimensions, limited negative surface charge, and poor stability in their aqueous suspensions, while the FCN aqueous suspension displayed the highest viscoelastic modulus due to the formation of highly entangled network. In paper coatings, SCN exhibited superior thickening and promoted rheological function due to their highly charged surface and strong interactions with pigments and immobilized water molecules, in comparison with other NC products. This study verified that the NC derived from CCR could be utilized as green and renewable additives to improve rheological properties for paper coatings
High Extinction Coefficient Thieno[3,4-b]thiophene-Based Copolymer for Efficient Fullerene-Free Solar Cells with Large Current Density
No full textA thieno[3,4-b]thibphene-based donor polymer PTBTz-2 was employed to construct fullerene-free solar cell with the classical acceptor ITIC. Interestingly, due to the high extinction coefficients and wide absorption for these two materials, the active layer can harvest a larger fraction of the coverage solar spectrum even in ultrathin film. Furthermore, the simultaneous advantages of appropriate cascade energy level, well-balanced hole/electron mobility (mu(h)/mu(e) = 1.16), and low charge accumulation and recombination, make the PTBTz-2/ITIC-based solar cells exhibit an excellent power conversion efficiency of 10.92% with large short circuit current density of 20.34 mA cm(-2). The results indicate that fine-tailored thieno [3,4-b]thiophene-based polymers would be another type of promising donor materials, except for widely reported efficient benzo[d][1,2,3]triazole (BTA)- or benzo[1,2-c:4,5-c']-dithiophene-4,8-dione (BDD)-based polymers, and would enrich the reservoir of high-performance light-harvesting conjugated polymers
Initial state-specific photodissociation dynamics of pyrrole via (1)pi sigma*/S-0 conical intersection initiated with optimally controlled UV-laser pulses
No full textOptimal initiation of quantum dynamics of N-H photodissociation of pyrrole on the S-0-(1)pi sigma*((1)A(2)) coupled electronic states by UV-laser pulses in an effort to guide the subsequent dynamics to dissociation limits is studied theoretically. Specifically, the task of designing optimal laser pulses that act on initial vibrational states of the system for an effective UV-photodissociation is considered by employing optimal control theory. The associated control mechanism(s) for the initial state dependent photodissociation dynamics of pyrrole in the presence of control pulses is examined and discussed in detail. The initial conditions determine implicitly the variation in the dissociation probabilities for the two channels, upon interaction with the field. The optimal pulse corresponds to the objective fixed as maximization of overall reactive flux subject to constraints of reasonable fluence and quantum dynamics. The simple optimal pulses obtained by the use of genetic algorithm based optimization are worth an experimental implementation given the experimental relevance of pi sigma*-photochemistry in recent times
Effects of graphene with different sizes as conductive additives on the electrochemical performance of a LiFePO4 cathode
No full textThis paper aims to demonstrate whether graphene nanosheets (GN) with different sizes as conductive additives are able to affect the electrochemical performance of a LiFePO4 (LFP) cathode. The results of electrochemical measurements present that graphene nanosheets (GN) and Super-P (SP) used as conductive additives simultaneously could construct an effective electronic conducting network and achieve excellent electrochemical performance when compared with traditional carbon materials. A LFP with small-size GN shows better specific capacity and rate performance than those with medium-size and large-size GN, and the LFP with large-size GN displays a poor rate performance. The results indicate that the specific capacity and rate performance tend to worsen with the increase of the size of graphene, owing to the length of the lithium ion transport path being prolonged and the ionic conductivity decreasing greatly by the " barrier effect" of graphene