Browsing by Author "Li, Feng"

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Acid-Stable Cu Cluster Precatalysts Enable High Energy and Carbon Efficiency in CO2 Electroreduction
(ACS, 2024-10-09) Kim, Dongha; Park, Sungjin; Lee, Junwoo; Chen, Yiqing; Li, Feng; Kim, Jiheon; Bai, Yang; Huang, Jianan Erick; Liu, Shijie; Jung, Eui Dae; Lee, Byoung-Hoon; Papangelakis, Panagiotis; Ni, Weiyan; Alkayyali, Tartela; Miao, Rui Kai; Li, Peihao; Liang, Yongxiang; Shayesteh Zeraati, Ali; Dorakhan, Roham; Meira, Debora Motta; Chen, Yanna; Sinton, David; Zhong, Mingjiang; Sargent, Edward H
The electrochemical reduction of CO2 in acidic media offers the advantage of high carbon utilization, but achieving high selectivity to C2+ products at a low overpotential remains a challenge. We identified the chemical instability of oxide-derived Cu catalysts as a reason that advances in neutral/alkaline electrolysis do not translate to acidic conditions. In acid, Cu ions leach from Cu oxides, leading to the deactivation of the C2+-active sites of Cu nanoparticles. This prompted us to design acid-stable Cu cluster precatalysts that are reduced in situ to active Cu nanoparticles in strong acid. Operando Raman and X-ray spectroscopy indicated that the bonding between the Cu cluster precatalyst ligand and in situ formed Cu nanoparticles preserves a high density of undercoordinated Cu sites, resulting in a C2H4 Faradaic efficiency of 62% at a low overpotential. The result is a 1.4-fold increase in energy efficiency compared with previous acidic CO2-to-C2+ electrocatalytic systems.
Active Aberration Correction with Adaptive Coefficient SPGD Algorithm for Laser Scanning Confocal Microscope
(2022-05-15) Zhou, Kunhua; Wu, Zhizheng; Zhang, Tianyu; Li, Feng; Iqbal, Azhar; Sivanandam, Suresh
A laser scanning confocal microscope (LSCM) is an effective scientific instrument for studying sub-micron structures, and it has been widely used in the field of biological detection. However, the illumination depth of LSCMs is limited due to the optical aberrations introduced by living biological tissue, which acts as an optical medium with a non-uniform refractive index, resulting in a significant dispersion of the focus of LSCM illumination light and, hence, a loss in the resolution of the image. In this study, to minimize the effect of optical aberrations, an image-based adaptive optics technology using an optimized stochastic parallel gradient descent (SPGD) algorithm with an adaptive coefficient is applied to the optical path of an LSCM system. The effectiveness of the proposed aberration correction approach is experimentally evaluated in the LSCM system. The results illustrate that the proposed adaptive optics system with an adaptive coefficient SPGD algorithm can effectively reduce the interference caused by aberrations during depth imaging.
Analyzing Japanese marsh warbler ( Megalurus pryeri ) song behavior in the breeding season
(Kunming Institute of Zoology, Chinese Academy of Sciences, 2011-08-17) Qu, Wen-Hui; Li, Feng; Sha, Jian-Bin; Zhang, Yu-Ming
Carbon- and energy-efficient ethanol electrosynthesis via interfacial cation enrichment
(Springer Science and Business Media LLC, 2024-10-04) Shayesteh Zeraati, Ali; Li, Feng; Tartela Alkayyali, Tartela; Dorakhan, Roham; Shirzadi, Erfan; Arabyarmohammadi, Fatemeh; O’Brien, Colin P; Gabardo, Christine M; Kong, Jonathan; Ozden, Adnan; Zargartalebi, Mohammad; Zhao, Yong; Fan, Lizhou; Papangelakis, Panagiotis; Kim, Dongha; Park, Sungjin; Miao, Rui Kai; Edwards, Jonathan P; Young, Daniel; Ip, Alexander H; Sargent, Edward H; Sinton, David
The use of acidic electrolytes in CO2 reduction avoids costly carbonate loss. However, the energy efficiency of acid-fed electrolysers has been limited by high hydrogen production and operating potentials. We find that these stem from the lack of alkali cations at the catalyst surface, limiting CO2 and CO adsorption. In acid-fed membrane electrode assembly systems, the incorporation of these cations is challenging as there is no flowing catholyte. Here an interfacial cation matrix (ICM)–catalyst heterojunction is designed that directly attaches to the catalyst layer. The negatively charged nature of the ICM enriches the alkali cation concentration near the cathode surface, trapping generated hydroxide ions. This increases the local electric field and pH, increasing multi-carbon production. Integrating the ICM strategy with a tailored copper–silver catalyst enables selective ethanol production through a proton-spillover mechanism. We report a 45% CO2-to-ethanol Faradaic efficiency at 200 mA cm−2, carbon efficiency of 63%, full-cell ethanol energy efficiency of 15% (3-fold improvement over the best previous acidic CO2 reduction value) and energy cost of 260 GJ per tonne ethanol, the lowest among reported ethanol-producing CO2 electrolysers.
Cationic-group-functionalized electrocatalysts enable stable acidic CO2 electrolysis
(Nature Research, 2023-09) Fan, Mengyang; Huang, Jianan Erick; Miao, Rui Kai; Mao, Yu; Ou, Pengfei; Li, Feng; Li, Xiao-Yan; Cao, Yufei; Zhang, Zishuai; Zhang, Jinqiang; Yan, Yu; Ozden, Adnan; Ni, Weiyan; Wang, Ying; Zhao, Yong; Chen, Zhu; Khatir, Behrooz; O’Brien, Colin P.; Xu, Yi; Xiao, Yurou Celine; Waterhouse, Geoffrey I. N.; Golovin, Kevin; Wang, Ziyun; Sargent, Edward H.; Sinton, David
Acidic electrochemical CO2 reduction (CO2R) addresses CO2 loss and thus mitigates the energy penalties associated with CO2 recovery; however, acidic CO2R suffers low selectivity. One promising remedy—using a high concentration of alkali cations—steers CO2R towards multi-carbon (C2+) products, but these same alkali cations result in salt formation, limiting operating stability to <15 h. Here we present a copper catalyst functionalized with cationic groups (CG) that enables efficient CO2 activation in a stable manner. By replacing alkali cations with immobilized benzimidazolium CG within ionomer coatings, we achieve over 150 h of stable CO2R in acid. We find the water-management property of CG minimizes proton migration that enables operation at a modest voltage of 3.3 V with mildly alkaline local pH, leading to more energy-efficient CO2R with a C2+ Faradaic efficiency of 80 ± 3%. As a result, we report an energy efficiency of 28% for acidic CO2R towards C2+ products and a single-pass CO2 conversion efficiency exceeding 70%.
Direct air capture of CO2via cyclic viologen electrocatalysis
(Royal Society of Chemistry, 2024-01-10) Liu, Shijie; Zhang, Jinqiang; Li, Feng; Edwards, Jonathan P.; Xiao, Yurou Celine; Kim, Dongha; Papangelakis, Panagiotis; Kim, Jiheon; Elder, David; De Luna, Phil; Fan, Mengyang; Lee, Geonhui; Miao, Rui Kai; Ghosh, Tanushree; Yan, Yu; Chen, Yuanjun; Zhao, Yong; Guo, Zunmin; Tian, Cong; Li, Peihao; Xu, Yi; Sargent, Edward H.; Sinton, David
Electrochemical direct air capture (DAC) can leverage renewable electricity to reduce atmospheric CO2 levels via energy-efficient organic redox couples. However, current organic systems are threatened by oxidative degradation when explosed to air. In this work, we propose an electrochemical process to regenerate hydroxide absorbents via cyclic viologen electrocatalysis (CVE). This strategy isolates the redox-active viologens from the alkaline absorbents to avoid oxidative degradation and vaporization loss. Tuning the viologen substituent is needed to facilitate fast reaction kinetics in the electric fields present under reductive and oxidative environments. We show that di-polar viologens, which contain both positively and negatively charged groups, can overcome electric field repulsion during reduction and oxidation. We demonstrate a minimum work of 0.82 GJ per tCO2, calculated based on the cyclic voltammetry redox potentials, and a work as low as 3.8 GJ per tCO2 in a practical two-electrolyser CVE configuration with over 200 hours of stable operation.
Efficient ethylene electrosynthesis through C–O cleavage promoted by water dissociation
(Springer Nature, 2024-06-20) Liang, Yongxiang; Li, Feng; Miao, Rui Kai; Hu, Sunpei; Ni, Weiyan; Zhang, Shuzhen; Liu, Yanjiang; Bai, Yang; Wan, Haoyue; Ou, Pengfei; Li, Xiao-Yan; Wang, Ning; Park, Sungjin; Li, Fengwang; Zeng, Jie; Sinton, David; Sargent, Edward H.
Electrochemical reduction of carbon monoxide is a promising carbonate-free approach to produce ethylene using renewable electricity. However, the performance of this process suffers from low selectivity and energy efficiency. A priority has been to weaken water dissociation with the aim of inhibiting the competing hydrogen evolution reaction but when this path was examined by replacing H2O with D2O, a further-reduced selectivity toward ethylene was observed. Here we examine approaches to promote water adsorption and to decrease the energy barrier to the ensuing water dissociation step, which could promote C–O cleavage in *CHCOH hydrogenation to *CCH. We modified a copper catalyst with the strong electron acceptor 7,7,8,8-tetracyanoquinodimethane, which made the catalyst surface electron deficient. The observed ethylene Faradaic efficiency was 75%, 1.3 times greater than that of unmodified copper control catalysts. A full-cell energy efficiency of 32% was achieved for a total projected energy cost of 154 GJ t−1 in ethylene electrosynthesis in a membrane electrode assembly.
Employee Stock Options, Equity Valuation, and the Valuation of Option Grants Using a Warrant-Pricing Model
(Wiley, 2005-01-11) Wong, M. H. Franco; Li, Feng
We investigate the use of a warrant-pricing approach to incorporate employee stock options (ESOs) into equity valuation and to account for the dilutive effect of ESOs in the valuation of option grants for financial reporting purposes. Our valuation approach accounts for the jointly determined nature of ESO and shareholder values. The empirical results show that our stock price estimate exhibits lower prediction errors and higher explanatory powers for actual share price than does the traditional stock price estimate. We use our valuation approach to assess the implications of dilution on the fair-value estimates of ESO grants. We find that the fair value is overstated by 6% if we ignore the dilutive feature of ESOs. Furthermore, this bias is larger for firms that are heavy users of ESOs, small, and R&D intensive, and for firms that have a broad-based ESO compensation plan.
Genome-wide identification, phylogeny and expression profile of the sucrose transporter multigene family in tobacco
(Canadian Science Publishing, 2018-12-07) Wang, Shanshan; Yang, Jun; Xie, Xiaodong; Li, Feng; Wu, Mingzhu; Lin, Fucheng; Wang, Zhong
The transportation and distribution of sucrose in plants is mediated by the sucrose transporters (SUTs), which also participate in various plant developmental and resistance processes. However, no such study of the tobacco SUT family has been reported yet. In the present study, 11, 5, and 4 SUT genes were identified from the Nicotiana. tabacum, N. sylvestris, and N. tomentosiformis genome, respectively. The exon/intron structures of the tobacco SUTs genes were highly conserved among the three tobacco species. There were gene loss, duplication, and chromosome exchange occurred to the NtSUT family during the formation of the allotetraploid common tobacco. Expression profiling analysis revealed that the expression patterns of the NtSUT genes in common tobacco were more close to those in the N. sylvestris plants. The NtSUT2s and NtSUT4 genes were ubiquitously expressed in various tobacco tissues, while the NtSUT1s gene was highly expressed in the maturing leaves, indicating their functional conservation and differentiation. The transcriptions of the NtSUT2t, NtSUT3s, NtSUT4 and NtSUT5s genes in tobacco plants were dramatically induced under Pi starvation, drought, and salinity stresses, but their highest expression levels occurred in different tissues, suggesting the multiple roles of NtSUTs in plant resistance to various abiotic stresses. This study provides useful information for the further functional characterization of the SUT genes in tobacco.
Pathways to reduce the energy cost of carbon monoxide electroreduction to ethylene
(Elsevier, 2024-05-15) Alkayyali, Tartela; Zargartalebi, Mohammad; Ozden, Adnan; Arabyarmohammadi, Fatemeh; Dorakhan, Roham; Edwards, Jonathan P.; Li, Feng; Shayesteh Zeraati, Ali; Fan, Mengyang; Bazylak, Aimy; Sargent, Edward H.; Sinton, David
CO2 -to-CO conversion, followed by CO to value-added products, shows promise as a high-CO2 utilization strategy. However, it is necessary to continue to reduce the energy intensity of CO electrolysers. Modeling can untangle the highly coupled nature of these electrolysers and thereby accelerate their optimization. Here, we develop a CO electrolyser model, which we compare with experiments, and evaluate how it might be possible to attain CO-to-ethylene with the energy intensity approaching 110 GJ tonne-1 C 2 H4 , then further to an 80 GJ tonne-1 C 2 H4 target. The model identifies targets and specifications for each component, with the ultimate target requiring continued progress in increasing cathodic catalyst selectivity; thin anion exchange membranes (<25 μm); improved ion exchange capacity (1.7 – 3.4 mmol/g); enhanced anode activity (>56% overpotential reduction) and thickness (100 – 400 μm); and optimized operation (1 – 4 M KOH at 25 – 75°C) at >300 mA cm -2 .
Site-selective protonation enables efficient carbon monoxide electroreduction to acetate
(2024-01) Wang, Xinyue; Chen, Yuanjun; Li, Feng; Miao, Rui Kai; Huang, Jianan Erick; Zhao, Zilin; Li, Xiao-Yan; Dorakhan, Roham; Chu, Senlin; Wu, Jinhong; Zheng, Sixing; Ni, Weiyan; Kim, Dongha; Park, Sungjin; Liang, Yongxiang; Ozden, Adnan; Ou, Pengfei; Hou, Yang; Sinton, David; Sargent, Edward H
Electrosynthesis of acetate from CO offers the prospect of a low-carbon-intensity route to this valuable chemical--but only once sufficient selectivity, reaction rate and stability are realized. It is a high priority to achieve the protonation of the relevant intermediates in a controlled fashion, and to achieve this while suppressing the competing hydrogen evolution reaction (HER) and while steering multicarbon (C2+) products to a single valuable product--an example of which is acetate. Here we report interface engineering to achieve solid/liquid/gas triple-phase interface regulation, and we find that it leads to site-selective protonation of intermediates and the preferential stabilization of the ketene intermediates: this, we find, leads to improved selectivity and energy efficiency toward acetate. Once we further tune the catalyst composition and also optimize for interfacial water management, we achieve a cadmium-copper catalyst that shows an acetate Faradaic efficiency (FE) of 75% with ultralow HER (<0.2% H2 FE) at 150 mA cm-2. We develop a high-pressure membrane electrode assembly system to increase CO coverage by controlling gas reactant distribution and achieve 86% acetate FE simultaneous with an acetate full-cell energy efficiency (EE) of 32%, the highest energy efficiency reported in direct acetate electrosynthesis.
Solid alveolar rhabdomyosarcoma with spindle-shaped cells and epithelial differentiation of the mediastinum in a 68-year-old man: A case report and literature review
(Medknow Publications on behalf of the Association of Radiation Oncologists of India (AROI), 2012-02-20) Qi, Yan; Chang, Bin; Pang, Lijuan; Liu, Chunxia; Li, Feng