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result(s) for
"Peng, Jie"
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Large magnetoresistance in LaBi: origin of field-induced resistivity upturn and plateau in compensated semimetals
The discovery of non-magnetic extreme magnetoresistance (XMR) materials has induced great interest because the XMR phenomenon challenges our understanding of how a magnetic field can alter electron transport in semimetals. Among XMR materials, the LaSb shows XMR and field-induced exotic behaviors but it seems to lack the essentials for these properties. Here, we study the magnetotransport properties and electronic structure of LaBi, isostructural to LaSb. LaBi exhibits large MR as in LaSb, which can be ascribed to the nearly compensated electron and hole with rather high mobilities. More importantly, our analysis suggests that the XMR as well as field-induced resistivity upturn and plateau observed in LaSb and LaBi can be well explained by the two-band model with the compensation situation. We present the critical conditions leading to these field-induced properties. It will contribute to the understanding of the XMR phenomenon and explore novel XMR materials.
Journal Article
Trends in oxygenate/hydrocarbon selectivity for electrochemical CO(2) reduction to C2 products
The electrochemical conversion of carbon di-/monoxide into commodity chemicals paves a way towards a sustainable society but it also presents one of the great challenges in catalysis. Herein, we present the trends in selectivity towards specific dicarbon oxygenate/hydrocarbon products from carbon monoxide reduction on transition metal catalysts, with special focus on copper. We unveil the distinctive role of electrolyte pH in tuning the dicarbon oxygenate/hydrocarbon selectivity. The understanding is based on density functional theory calculated energetics and microkinetic modeling. We identify the critical reaction steps determining selectivity and relate their transition state energies to two simple descriptors, the carbon and hydroxide binding strengths. The atomistic insight gained enables us to rationalize a number of experimental observations and provides avenues towards the design of selective electrocatalysts for liquid fuel production from carbon di-/monoxide.
Key mechanistic steps for selective CO
(2)
reduction over Cu into hydrocarbon versus oxygenated C
2
products are identified by atomistic and microkinetic modeling. Variations in C and OH binding are found to predict catalytic selectivity of materials.
Journal Article
Efficient purification of ethene by an ethane-trapping metal-organic framework
Separating ethene (C
2
H
4
) from ethane (C
2
H
6
) is of paramount importance and difficulty. Here we show that C
2
H
4
can be efficiently purified by trapping the inert C
2
H
6
in a judiciously designed metal-organic framework. Under ambient conditions, passing a typical cracked gas mixture (15:1 C
2
H
4
/C
2
H
6
) through 1 litre of this C
2
H
6
selective adsorbent directly produces 56 litres of C
2
H
4
with 99.95%+ purity (required by the C
2
H
4
polymerization reactor) at the outlet, with a single breakthrough operation, while other C
2
H
6
selective materials can only produce
ca
. ⩽ litre, and conventional C
2
H
4
selective adsorbents require at least four adsorption–desorption cycles to achieve the same C
2
H
4
purity. Single-crystal X-ray diffraction and computational simulation studies showed that the exceptional C
2
H
6
selectivity arises from the proper positioning of multiple electronegative and electropositive functional groups on the ultramicroporous pore surface, which form multiple C–H···N hydrogen bonds with C
2
H
6
instead of the more polar competitor C
2
H
4
.
The separation of high purity ethene from the mixed gaseous products of cracking poses significant obstacles. Here, the authors present a metal-organic framework which, in contrast to most absorbents, selectively binds the less polar ethane thus allowing the efficient collection of the target product.
Journal Article
Advanced energy materials for flexible batteries in energy storage: A review
Smart energy storage has revolutionized portable electronics and electrical vehicles. The current smart energy storage devices have penetrated into flexible electronic markets at an unprecedented rate. Flexible batteries are key power sources to enable vast flexible devices, which put forward additional requirements, such as bendable, twistable, stretchable, and ultrathin, to adapt mechanical deformation under the working conditions. This review summarizes the recent advances in construction and configuration of flexible batteries and discusses the general metrics to benchmark various flexible batteries with different materials and chemistries. Moreover, we present advanced prototype flexible batteries developed by some companies to afford general envision of the technological status. Lastly, the critical points are summarized in the development of flexible batteries and remaining challenges are also presented for the future design of flexible batteries in practical perspectives.
Flexible batteries are key power sources to smart energy storage. This review summarizes the recent advances of flexible batteries and affords perspectives on the design of efficient battery components and configurations.
Journal Article
Controlling guest conformation for efficient purification of butadiene
Conventional adsorbents preferentially adsorb the small, high-polarity, and unsaturated 1,3-butadiene molecule over the other C₄ hydrocarbons from which it must be separated. We show from single-crystal x-ray diffraction and computational simulation that a hydrophilic metal-organic framework, [Zn₂(btm)₂], where H₂btm is bis(5-methyl-1H-1,2,4-triazol-3-yl)methane, has quasi-discrete pores that can induce conformational changes in the flexible guest molecules, weakening 1,3-butadiene adsorption through a large bending energy penalty. In a breakthrough operation at ambient temperature and pressure, this guest conformation–controlling adsorbent eluted 1,3-butadiene first, then butane, butene, and isobutene. Thus, 1,3-butadiene can be efficiently purified (≥99.5%) while avoiding high-temperature conditions that can lead to its undesirable polymerization.
Journal Article
Influence of temperature on microbially induced calcium carbonate precipitation for soil treatment
Microbially induced calcium carbonate precipitation (MICP) is a potential method for improvement of soil. A laboratory study was conducted to investigate the influence of temperatures for soil improvement by MICP. The ureolytic activity experiments, MICP experiments in aqueous solution and sand column using Sporosarcina pasteurii were conducted at different temperatures(10, 15, 20, 25 and 30°C). The results showed there were microbially induced CaCO3 precipitation at all the temperatures from 10 to 30°C. The results of ureolytic activity experiments showed that the bacterial had higher ureolytic activity at high temperatures within the early 20 hours, however, the ureolytic activity at higher temperatures decreased more quickly than at lower temperatures. The results of MICP experiments in aqueous solution and sand column were consistent with tests of ureolytic activity. Within 20 to 50 hours of the start of the test, more CaCO3 precipitation was precipitated at higher temperature, subsequently, the precipitation rate of all experiments decreased, and the higher the temperature, the faster the precipitation rate dropped. The final precipitation amount of CaCO3 in aqueous solution and sand column tests at 10 °C was 92% and 37% higher than that at 30 °C. The maximum unconfined compressive strength of MICP treated sand column at 10 °C was 135% higher than that at 30 °C. The final treatment effect of MICP at lower temperature was better than that at high temperature within the temperature range studied. The reason for better treatment effect at lower temperatures was due to the longer retention time of ureolytic activity of bacteria at lower temperatures.
Journal Article
Dynamic rhenium dopant boosts ruthenium oxide for durable oxygen evolution
Heteroatom-doping is a practical means to boost RuO
2
for acidic oxygen evolution reaction (OER). However, a major drawback is conventional dopants have static electron redistribution. Here, we report that Re dopants in Re
0.06
Ru
0.94
O
2
undergo a dynamic electron accepting-donating that adaptively boosts activity and stability, which is different from conventional dopants with static dopant electron redistribution. We show Re dopants during OER, (1) accept electrons at the on-site potential to activate Ru site, and (2) donate electrons back at large overpotential and prevent Ru dissolution. We confirm via in situ characterizations and first-principle computation that the dynamic electron-interaction between Re and Ru facilitates the adsorbate evolution mechanism and lowers adsorption energies for oxygen intermediates to boost activity and stability of Re
0.06
Ru
0.94
O
2
. We demonstrate a high mass activity of 500 A g
cata.
−1
(7811 A g
Re-Ru
−1
) and a high stability number of S-number = 4.0 × 10
6
n
oxygen
n
Ru
−1
to outperform most electrocatalysts. We conclude that dynamic dopants can be used to boost activity and stability of active sites and therefore guide the design of adaptive electrocatalysts for clean energy conversions.
RuO
2
is a promising anode catalyst for proton exchange membrane water electrolyzers but suffers from poor catalytic stability. Here the authors present a rhenium-doped RuO
2
with a unique dynamic electron accepting-donating that adaptively boosts activity and stability in acidic water oxidation.
Journal Article
English Language Teaching Methods: Exploring the Impact of Various Approaches on Students’ Language Learning Outcomes
This scholarly paper embarks on an in-depth exploration within the domain of English language teaching methodologies, casting a spotlight on three innovative approaches: immersive teaching, task-based teaching, and reflective teaching. Each of these methods represents a unique strategy in the broader context of language pedagogy, aimed at enhancing the efficacy of language acquisition among learners. By meticulously examining the effectiveness of each approach in fostering language learning outcomes, this study makes a significant contribution to the ongoing scholarly conversation about the most effective methods for teaching languages. Through an exhaustive review and analysis of both existing literature and empirical evidence, the paper illuminates the distinct advantages and potential limitations inherent in each of these teaching strategies. Immersive teaching, with its focus on surrounding learners with the target language in context, aims to simulate the natural language acquisition processes. Task-based teaching, on the other hand, emphasizes the completion of meaningful tasks that require language use, thereby promoting practical language skills in real-world contexts. Reflective teaching introduces a critical component, encouraging both teachers and learners to reflect on their experiences, strategies, and outcomes to continuously adapt and improve the learning process. By offering educators a nuanced understanding of these diverse approaches, the paper provides valuable insights into how language education can be optimized to meet the varied needs of learners. It highlights the importance of selecting and tailoring teaching methodologies to suit specific educational contexts and learner profiles, thus enhancing the overall effectiveness of language learning programs. This comprehensive analysis not only aids educators in making informed decisions about their teaching practices but also contributes to the development of more dynamic, responsive, and effective language teaching and learning environments.
Journal Article
Electrosynthesis of polymer-grade ethylene via acetylene semihydrogenation over undercoordinated Cu nanodots
The removal of acetylene impurities remains important yet challenging to the ethylene downstream industry. Current thermocatalytic semihydrogenation processes require high temperature and excess hydrogen to guarantee complete acetylene conversion. For this reason, renewable electricity-based electrocatalytic semihydrogenation of acetylene over Cu-based catalysts is an attractive route compared to the energy-intensive thermocatalytic processes. However, active Cu electrocatalysts still face competition from side reactions and often require high overpotentials. Here, we present an undercoordinated Cu nanodots catalyst with an onset potential of −0.15 V versus reversible hydrogen electrode that can exclusively convert C
2
H
2
to C
2
H
4
with a maximum Faradaic efficiency of ~95.9% and high intrinsic activity in excess of −450 mA cm
−2
under pure C
2
H
2
flow. Subsequently, we successfully demonstrate simulated crude ethylene purification, continuously producing polymer-grade C
2
H
4
with <1 ppm C
2
H
2
for 130 h at a space velocity of 1.35 × 10
5
ml g
cat
−1
h
−1
. Theoretical calculations and in situ spectroscopies reveal a lower energy barrier for acetylene semihydrogenation over undercoordinated Cu sites than nondefective Cu surface, resulting in the excellent C
2
H
2
-to-C
2
H
4
catalytic activity of Cu nanodots.
Cu-based catalysts for the conversion of C
2
H
2
to C
2
H
4
are plagued by side reactions. Here, Cu nanodots for C
2
H
2
semihydrogenation are reported to reach current densities >400 mA cm
−2
and selectively produce polymer-grade ethylene over 130 h.
Journal Article