Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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Investigation on the cleavage of beta-O-4 linkage in dimeric lignin model compound over nickel catalysts supported on ZnO-Al2O3 composite oxides with varying Zn/Al ratios
No full textCatalytic depolymerization of lignin is still a challenge due to its low conversion and repolymerization of the reactive intermediates. Reductive depolymerization over supported nickel catalysts with probable surface acidic and basic properties is a very promising process. It is therefore very important to investigate the effect of acidity and basicity of the supports on catalytic reactivity. In this paper, we synthesized a series of nickel based catalysts supported on ZnO-Al2O3 composites with varying Zn/Al atom ratios (Zn/Al = 2, 3, 5, 8) and tested their catalytic performances over a model compound 2-phenoxy-1-phenylethanone containing beta-O-4 bond. All these catalysts showed 100% conversion by reacting at 250 degrees C for 2 h under 2 MPa of H-2. Higher selectivity towards ethylcyclohexane could be obtained over the catalyst Ni/ZnO-Al2O3-5. The possible cleavage pathways of selective oxidized beta-O-4 ether linkage have been proposed
Multivariate data analysis applied in alkali-based pretreatment of corn stover
No full textIn this paper, variables of Pulp Refining Instrument (PFI) refining assisted alkaline pretreatment and hydrolysis saccharification of corn stover were analyzed. The process parameters were characterized by multivariate data analysis methods including Principle Component Analysis and Partial Least Square (PCA and PLS) to investigate the specific relationships of primary variables in alkali-based pretreatment of biomass. In this paper, pretreatment system was multivariate and the variables were inter-related to each other. Total alkaline charge and removal rate of lignin had greatest impact on the pretreatment and enzymatic hydrolysis. (C) 2016 Published by Elsevier B.V
Effect of electrode potentials on the microbial community of photo bioelectrochemical systems
No full textIncreasing attention is being paid to the adoption of photoautotrophic microbes in bioelectrochemical systems (BESs) because of the advantages of self-sustainability. Biased potential on the anode was capable of adjusting the performance of non-photo BESs, and the microbial community structure was also changed; however, few studies have been conducted to investigate the effects of potential on microbial community structure in photo-BESs. In this work, the response of microbial community structure to different potentials (i.e., 0, 0.2, 0.4 and 0.6 V vs. Ag/AgCl) was characterized with 454 pyrosequencing. Four samples were collected and they generated 42865 16S rDNA sequencing reads with an average length of 429 bp. The potential at 0.2 V resulted in the highest current density (378.8 mA m(-2)) and showed a strong selection for.-proteobacteria (30.8% of the sequences). alpha-Diversity analysis showed that microbial diversity increased with increased potential. Rhodopseudomonas palustris was dominant among known exoelectrogens in the biofilm biased at 0.4 V. The results provided an insight into the mechanism of potential regulation on the performance of photo-BESs and changes in microbial community structure
High Performance Lithium Secondary Batteries Based on Novel Ni3Co6S8@C Core-Shell Nanoparticle
No full textAs one new type of cathode materials, transition metal sulfides with the advantages of high energy density and high electronic conductivity have attracted a lot of attentions to fulfill the demands of high power and energy battery applications in hybrid electric vehicles (HEVs) and electric vehicles (EVs). Herein, we report the synthesis of one novel ternary sulfide of Ni3Co6S8@C urchin-like core-shell nanoparticles as cathode materials for lithium secondary batteries with sodium alginate as the binder and lithium foil as the anode. The novel Ni3Co6S8@C nanoparticles show high discharge specific capacity, excellent cycling stability and much better rate capability. Based on the overall mass of the Ni3Co6S8@C nanoparticles, it could achieve an initial energy density of 957 Wh kg(-1), and a respective energy density of 606 and 508 Wh kg(-1) after 100 and 200 cycles. The outstanding performance of the Ni3Co6S8@C electrode could be attributed to the carbon coating and sodium alginate binder, because these strategies could significantly inhibit the volume change, aggregation and pulverization of Ni3Co6S8@C nanoparticles
Graphene-Encapsulated Copper tin Sulfide Submicron Spheres as High-Capacity Binder-Free Anode for Lithium-Ion Batteries
No full textbased sulfides are potential anode materials for lithium-ion batteries (LIBs); nevertheless, they typically suffer from poor cycle stability resulted from the huge volume variation during lithium-ion insertion and extraction. Herein, we successfully fabricated the multiphase Cu2Sn3S7/Cu2SnS3/SnS2 (CTS) submicron spheres uniformly incorporated with reduced graphene oxide nanosheets (CTS@RGO). This binder-free hybrid CTS@RGO paper exhibits favorable capacity retention as an anode of LIBs (965 mAhg(-1) after 300 cycles at current density of 500 mAg(-1)), as well as better rate capability and high initial coulombic efficiency compared with that of a pristine CTS anode. The enhanced electrochemical performance can be ascribed to the introduction of graphene as a buffer to accommodate large volume changes and to maintain structural integrity of electrode
Enhanced Electrochemical Performance of LiMn0.75Fe0.25PO4 Nanoplates from Multiple Interface Modification by Using Fluorine-Doped Carbon Coating
No full textWe report a novel composite of fluorine-doped carbon-decorated LiMn0.75Fe0.25PO4 (LMFP) nanoplates synthesized via a facile method by using hybrid sucrose and polyvinylidene fluoride as carbon and fluorine sources. In the composite, the thin LMFP nanoplates expose large amounts of (010) crystal face which shortens the Li+ ion diffusion distance. Also, the fluorine-doped carbon coating layer can provide a sufficient pathway for rapid electron transport, and the partially formed metal fluorides in the interface between the LMFP nanoplates surface and fluorine-doped carbon coating layer will help reduce charge transfer resistance. Because of this unique structure, the resulting product exhibits a superior discharge capacity of 162.2 mA h g(-1) at the 1 C current rate, and the capacity is retained 94.8% over 200 cycles. Furthermore, this material also can deliver a reversible capacity of 130.3 mA h g(-1) at an ultrahigh current rate of 20 degrees C, in which the discharge procedure can be accomplished only in 144 s. The celerity and cycling capability of the prepared material endow it with great potential for application in high performance lithium-ion batteries
Blended additive manipulated morphology and crystallinity transformation toward high performance perovskite solar cells
No full textThe efficiency of a perovskite solar cell is highly affected by the crystal quality and morphology of its perovskite layer. A facile strategy of using blended organic additives to regulate the film's crystallinity and coverage is studied in this work. The coordination behavior and sublimation temperature of the additives are the essential characteristics which determine the quality of the perovskite films. By introducing a certain amount of MACl, a kind of crystallinity-preferred additive, to partially replace MAAc, a coverage-preferred additive, the film's crystallinity has been obviously improved at no expense of coverage, which results in a lower trap density, higher efficiency and better stability
Efficient fullerene-free solar cells with wide optical band gap polymers based on fluorinated benzotriazole and asymmetric benzodithiophene
No full textIn this work, alpha- and beta-position naphthalene substituents as side chains on asymmetric BDT were used as donor building blocks to build wide bandgap (WBG) donor materials (P alpha NBDT-T1 and P beta NBDT-T1) with fluorinated benzotriazole (T1) as the acceptor unit. The two co-polymers were used to build polymer solar cells (PSCs) with PC71BM or ITIC acceptor material. In ITIC acceptor material based devices, the P alpha NBDT-T1 co-polymer with a larger dihedral angle between main backbone and naphthalene ring achieved a higher power conversion efficiency (PCE) of 9.60% with improved short-circuit current density (J(SC)) and fill factor (FF) compared with P beta NBDT-T1, which was ascribed to the excellent morphology of the blended film. The open circuit voltage (V-OC) was also maintained at a decent level upon introducing these naphthalene rings due to their high ionization potential and low electron density. Interestingly, for PC71BM based devices, the two polymers show a reverse situation compared with an ITIC system. The P beta NBDT-T1 with a small dihedral angle between the main backbone and naphthalene rings shows a slightly higher performance than P alpha NBDT-T1. However, in the PC71BM system, both polymers did not exhibit ideal optical performance due to their unmatched absorption spectrum. These phenomena indicate that the asymmetric BDTs have great potential towards achieving high optical performance with non-fullerene acceptor materials
Mechanistic Insights into Ethylene Transformations on Ir(111) by Density Functional Calculations and Microkinetic Modeling
No full textEthylidyne, ethane, and carbon monomer formations from ethylene over Ir(111) at different coverages are investigated using density functional theory methods. Two possible reaction mechanisms for ethylidyne formation are investigated. The calculations show that vinyl prefers the dehydrogenation to yield vinylidene (M2) over the hydrogenation to produce ethylidene (M1) kinetically and thermodynamically at 1/9 (1/3) ML. Ethylidyne formation could be a competitive side reaction of ethylene hydrogenation, however, the ethylidyne species does not directly participate in the ethylene hydrogenation mechanism. The mechanism for C monomer formation is also studied. Microkinetic modeling shows that the ethylene hydrogenation reactivity decreases in the sequence Ir(111) > Rh(111) > Pd(111) > Pt(111) under typical hydrogenation conditions. The catalytic activity of ethylene hydrogenation decreases with increased stability of ethylene adsorption and reaction barrier of the rate-limiting step
Entropy drives the formation of salt bridges in the protein GB3
No full textSalt bridges are very common in proteins. But what
drives the formation of protein salt bridges is not clear. In this
work, we determined the strength of four salt bridges in the
protein GB3 by measuring the DpKa values of the basic
residues that constitute the salt bridges with a highly accurate
NMR titration method at different temperatures. The results
show that the DpKa values increase with temperature, thus
indicating that the salt bridges are stronger at higher temperatures.
Fitting of DpKa values to the vanQt Hoff equation yields
positive DH and DS values, thus indicating that entropy drives
salt-bridge formation. Molecular dynamics simulations show
that the protein and solvent make opposite contributions to DH
and DS. Specifically, the enthalpic gain contributed from the
protein is more than offset by the enthalpic loss contributed
from the solvent, whereas the entropic gain originates from the
desolvation effect