ANALYTICAL CHEMISTRY
·
2022
·
IF 8.008
Yamin Ma,Cheng Liu,Lishi Wang
A strategy for the fast analysis of ion transfer/facilitated ion transfer toward a tiny (femtoliter) water-in-oil droplet has been established. This scenario is embodied by the fusion of a w/o microdroplet at the micro liquid/liquid (L/L) interface, with the use of Fourier transform fast-scan cyclic voltammetry (FT-FSCV) to express the apparent half-wave potentials of anions or cations encapsulated inside the w/o microdroplet. First, the half-wave potential is in strict accordance with the transfer Gibbs free energy of either cations or anions. Second, the half-wave potential has been found to be positively proportional to the logarithmic concentration of ions, shedding thermodynamic insight into ion transfer. Third, as an instance of multivalent biopolymers, the transfer of protamine inside the single w/o microdroplet has been investigated. Obvious discrepancies in the behaviors of the fusion impacts at different pH, as well as in the absence and presence of the cationic surfactant DNNS–, are revealed. The internal mechanism of protamine transfer has been thoroughly investigated. This work proposes a strategy to sensitively and quickly determine the transfer Gibbs energy and the concentration of ions encapsulated in a single microdroplet, and it provides the possibility of analyzing the interfacial transfer properties of trace biomacromolecules inside an aqueous micro- or nanoscale droplet.
研究领域:
分析化学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
International Journal of Electrochemical Science
·
2023
·
IF 1.5
Yuzhen Zhang,Jiangying Yu,Changwei Shao,Peichuan Sun,Chungang Min,Jianhua Wang,Xikun Yang
Effectively improving catalytic activity of nitrogen (N)-doped carbon catalysts in oxygen reduction reaction (ORR) is very important but still facing with challenges. Herein, we proposed a “solvent effect” strategy to prepare a high active N-doped carbon catalyst with trace iron (N-C-Fe-ethanol, 0.10 at.% Fe) via pyrolysis of polyaniline (PANI)-iron (Fe) coordination polymer washed with ethanol. Electrochemical results show that N-C-Fe-ethanol catalyst exhibits a remarkable 109 mV positive shift of half-wave potential compared with that of catalyst unwashed PANI-Fe coordination polymer, and its limiting current density (3.61 mA-cm -2 ) is closer to that of Pt/C catalyst in acid media. It was demonstrated that the surface structure of PANI-Fe coordination polymer could be tuned via removing some nitrogen-containing groups such as –N + = groups and other small molecules on its surface, which helped to generate a high ratio of graphitic N in the pyrolysis process. This work develops a new path for improving the ORR activity of N-doped carbon catalysts.
研究领域:
材料化学
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电催化
·
能源材料
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纳米催化
·
表面化学
✓ 已验证
DOI
高影响因子
JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
·
2021
·Vol. 36
·期 2
·166-173
·
IF 0.957
Tao Bowen,Pan Xiangchuan,Zhang Haining
Hollow nitrogen-doped porous carbon materials covered with different thicknesses of carbon layers were synthesized to assist evaluation of the influence of nitrogen atom on the surrounding carbon atoms. The designed carbon-based materials were synthesized through pyrolysis of surface-attached block copolymer layers on silica nanoparticles with different thicknesses of the second block of grafted polymer chains, followed by removal of silica templates. The experimental results reveal that coverage a carbon layer with proper thickness can improve the oxygen reaction reduction activity of nitrogen-doped carbon materials as evidenced by the positive shift of half-wave potential in linear scanning voltammetry response curves. The conclusions may provide a reference work on understanding the active sites and designing materials with superior electrochemical performance.
研究领域:
材料科学
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电化学
·
纳米材料
✓ 已验证
产品关联
DOI
高影响因子
POLYHEDRON
·
2024
·
IF 2.4
An-Na Chen,Yan-Ling Deng,Chun-Yang Pan
Two imidazole-based ligand-nickel borates, [Ni(1-ipIM) 3 ·B 6 O 7 (OH) 6 ]·[H 3 BO 3 ]·2·.5H 2 O ( 1 , 1-ipIM = 1-isopropylimidazole) and [Ni(1-pIM) 6 ]·[B 5 O 6 (OH) 4 ]·2H 2 O ( 2 , 1-pIM = 1-propylimidazole) have been synthesized and structurally characterized by single-crystal X-ray diffraction, PXRD, FTIR. The oxoboron cluster structures of 1 and 2 were modulated through changing the carbon-branched structure on the N -site of the imidazole-based ligand using metallic nickel as the central atom. It is noteworthy that the structure of 1 is a hybridized skeleton formed by N -Ni-O-B bonds. The electrocatalytic oxygen reduction reaction (ORR) activity of these borate-based catalysts was investigated. The half-wave potential ( E 1/2 ) values of 1 -based and 2 -based were about 0.825 and 0.80 V, respectively.
研究领域:
无机化学
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电化学
·
催化
✓ 已验证
产品关联
DOI
高影响因子
Industrial Chemistry & Materials
·
2024
·
IF 0
Jiayao Cui,Junyong Min,Hao Wang,Jianglan Shui,Lishan Peng,Zhenye Kang,Jieyuan Liu,Qingjun Chen,Shuo Bai,Yanrong Liu
Developing single-atom Fe–N4/C catalysts is crucial for the large-scale implementation of proton exchange membrane fuel cells (PEMFCs). While Fe–N4/C catalysts are inherently active in accelerating the slow ORR process, their performance is still inferior to that of Pt/C. Herein, a trace Co-doped Fe single-atom catalyst (Fe(tCo)–N–C) containing more active Fe2N8 sites has been synthesized. Interestingly, compared with typical FeN4 sites in an Fe–N–C electrocatalyst, the Fe2N8 sites generate a larger Fe–N bond length due to Co-doping. The elongated Fe–N bond in Fe2N8 lowers the d-band center and charge density of iron sites, enhancing the ORR process by facilitating the formation of *OOH and generation and desorption of *OH. Fe(tCo)–N–C manifested excellent acidic and alkaline ORR activity, with a half-wave potential (E1/2) of 0.80 V in HClO4 solution and 0.89 V in KOH medium. More importantly, high peak power densities (Pmax) were realized by applying Fe(tCo)–N–C in PEMFCs, with the Pmax reaching 890 mW cm−2 in H2–O2 and 380 mW cm−2 in H2–air. Additionally, trace Co dopants in the catalyst improved carbon graphitization and provided high ORR catalytic stability. This research introduces an innovative approach to engineering highly active Fe2N8 sites, providing valuable insights for the sustainable progress of PEMFC technology.
研究领域:
电化学
·
催化
·
能源材料
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燃料电池
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纳米技术
✓ 已验证
DOI
ACS Applied Materials & Interfaces
·
2022
·
IF 10.383
Yi Yang,Zhida Wang,Zheng Liang,Lisha Shen,Changqing Guo,Yan Shi,Hongyi Tan,Zhuoxin Lu,Changfeng Yan
Block-copolymer-derived ordered mesoporous carbon (OMC) materials have great potential in many applications, such as adsorption, catalysis, and energy conversions; however, their formation process and the kinetic mechanism remain unclear. Herein, a N-doped OMC (N-OMC) with sp2-bonded C atoms is developed via self-assembly of the polystyrene-block-poly(4-vinyl pyridine) block copolymer. By correlating the external morphologies with the internal chemical states, the formation process can be concluded as follows: (1) pore evolution via polystyrene domain degradation and (2) regularization and graphitization of the residual carbon via the removal of sp3 C atoms. In addition, the thickness of the N-OMC shows a power function relationship with the spin-coating rate, and the N content can be incredibly increased up to 26.34 at. % in an NH3 carbonization atmosphere. With the as-prepared N-OMC as the support for loading of the pseudo-atomic-scale Pt (Pt/N-OMC), a high electrochemical active surface area value of 99.64 m2·g–1 and a half-wave potential (E1/2) of 0.850 VRHE are achieved, showing great potential in developing single-atom electrocatalysts.
研究领域:
材料科学
·
化学
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纳米技术
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2024
·
IF 2.7
Kun Liu,Yujing Ling,Xianglong Guan,Ke Hu,Angli Zhang,Kaiqi Liu,Haoyi Li,Guangnian Xu,Xu-Cheng Fu
The commercialization of magnesia-air batteries (Mg-air) necessitates the development of highly efficient, cost-effective, and durable electrocatalysts for oxygen reduction reaction (ORR), replacing expensive and unstable precious metal electrocatalysts. A hard template-assisted synthesis of FeCo nanoparticles immobilized on N-doped porous carbon (Fe-Co-C-N) for the ORR is reported. The half-wave potential of Fe-Co-C-N for ORR (E1/2=0.88 V vs. RHE) is elevated by 40 mV compared to that of 20 wt% Pt/C (E1/2=0.84 vs. RHE). The catalyst exhibits exceptional catalytic performance and remarkable stability. The discharge voltage of the Mg-air battery, utilizing Fe-Co-C-N as the cathode catalyst (1.29 V), surpasses that of the battery employing 20 wt% Pt/C as the cathode catalyst (1.28 V). The Mg-air battery with Fe-Co-C-N as the cathode catalyst exhibited excellent discharge stability and maintained a stable discharge for over 200 hours. The present study offers valuable insights into the structural design and regulatory mechanisms governing the performance of M-N-C catalysts in Mg-air batteries.
研究领域:
材料科学
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电化学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POWER SOURCES
·
2025
·
IF 7.9
Lin Wu,Chunyu Ji,Xueyan Li,Zirui Liu,Hao Yang,Feng Qiu,Zhili Peng,Qingju Liu,Longzhou Zhang
Despite heteroatom doping is a smart approach to facilitate the oxygen reduction reaction (ORR) performances of nanocarbon catalysts, two dominant issues still retain as significant obstacles. One is the relatively low activity compared to benchmark catalysts, the other is the ambiguous elucidation of the catalytic mechanism for dual heteroatom-doped catalysts. Here, nitrogen and sulfur co-doped carbon-dots electrocatalyst (HT-CDs) are simply prepared by means of physical activation with water vapor on the carbon-dots precursor. The material exhibits excellent ORR performance under alkaline conditions, achieving a half-wave potential of 0.91 V (vs RHE), surpassing most metal-free catalysts and Pt/C. Further theoretical studies reveal that N/C-S-N structure fills more electrons in the anti-bond orbitals that promoting the charge transfer from the catalyst to the reactant O 2 , thus enhancing the efficient ORR process.
研究领域:
材料科学
·
电化学
·
纳米碳催化
·
能量转换
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS RESEARCH
·
2023
·Vol. 38
·期 9
·2359-2368
·
IF 2.7
Ma Junjie,Liu Hangcheng,Tao Zeyu,Liu Jianfeng,Yuan Binxia,Pan Weiguo,Shi Zhengrong
In order to reveal the relationship between the structure and the electrochemical oxygen reduction reaction (ORR) activity of different double transition metal decorated catalysts, three different double transition metal and N co-doped carbon material cathode catalyst materials (FeCo–NC, FeNi–NC and CoNi–NC) were prepared in this study. The FeCo–NC catalysts synthesised in this study still showed high ORR activity under alkaline conditions, with a half-wave potential of 0.783 V RHE , a mass activity (MA) of 11.36 A/g (0.77 V RHE ) and an ultimate current density of − 4.46 mA cm −2 ; after 30,000 cycles, the half-wave potential only decreased to 99.3% of the initial potential. Meanwhile, we employ MS to establish three different double transition metal and N co-doped graphene catalysts and to calculate and analyse their desorption properties, leading to the FeCo–NC material being the model with the highest ORR activity, which is consistent with the experimental results. Graphical Abstract
研究领域:
电化学
·
材料科学
·
催化
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2018
·
IF 11.698
Jingyu Wang,Min Xu,Jianquan Zhao,Huaifang Fang,Qingzhu Huang,Weiping Xiao,Tao Li,Deli Wang
The activity and stability of Pt electrocatalysts are crucial issues for energy conversion systems involving oxygen reduction reaction (ORR). In this work, the ultrafine Pt nanoparticles were in situ reduced by the photogenerated electrons on TiO 2 surface so that most of them selectively anchored around the TiO 2 nanocrystals. The presence of well-dispersed TiO 2 on carbon surface strengthened the metal-support interaction, giving rise to the improved ORR catalytic activity with ∼49 mV positive shift of half-wave potential as compared to commercial 20 wt% Pt/C. More importantly, the Pt/TiO 2 -C catalysts exhibited a more durable performance after 10,000 cycles in terms of the decrease in electrochemical surface area (0.8%) and mass activity (0.9%), much lower than those of Pt/C (10.2% and 33.3%). The high-temperature durability test also revealed a much higher retention of ORR activity. The results demonstrated that anchoring Pt on well-dispersed TiO 2 -decorated carbon would be an effective strategy to enhance the ORR performance by strong metal-support interaction, which facilitated the electron transfer during catalytic reactions as well as prevented Pt aggregation during durability test.
研究领域:
电催化
·
能源转换
·
纳米材料
·
表面科学
·
物理化学
·
材料化学
✓ 已验证
DOI
高影响因子
Nano Research
·
2024
·
IF 9.5
Gao Li,Song Yang,Xu Xuebing,Li Chang,Hu Chaoquan
In this study, a Mn-modified Pt-based catalyst loaded on nitrogen-doped Ketjen black (Mn-Pt/NKB) is prepared using a simple ethylene glycol reduction method. The size of Pt nanoparticles (NPs) is effectively controlled by doping with Mn and N. With the smallest average particle size of 1.7 nm, Mn-Pt/NKB demonstrates half-wave potentials of 0.890 and 0.688 V in the alkaline and neutral electrolytes, respectively, which are superior to those of commercial platinum on activated carbon (Pt/C). When applied as an air cathode in aluminum-air battery, it exhibits ultra-high power densities of 190 (alkaline) and 26.2 mW·cm −2 (neutral). Moreover, the voltage remains stable after 5 h of discharge. The practical application performance of the Mn-Pt/NKB catalyst in an aluminum-air battery is better than that of commercial Pt/C. Furthermore, the oxygen reduction reaction (ORR) mechanism on surfaces with different particle sizes is analyzed using density functional theory. Oxygen cracking is the major pathway on the surface of the small particles with lower energy consumption of 0.5 eV, while water molecule cleavage is the major pathway on the surface of the large particles with higher energy consumption of 0.97 eV. The lower energy consumption of the oxygen cracking pathway further confirms the ORR mechanism for higher activity on small-sized surfaces. This study provides a direction for the rational design of Pt-based catalysts for ORR and sheds light on the commercial development of aluminum-air batteries.
研究领域:
电化学
·
材料科学
·
能源存储
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2019
·
IF 8.456
Xiaodong Chen,Ning Wang,Kui Shen,Yangkai Xie,Yongpeng Tan,Yingwei Li
In order to improve the catalytic performance of oxygen reduction reaction (ORR), it is pivotal to increase the density and accessibility of the active sites. Herein, we have developed a template-free melamine-assisted cocalcined strategy to afford Fe-embedded and N-doped carbons (Fe–N–C) with not only high density of atomically dispersed Fe–Nx active sites but also abundant three-dimensional interconnected mesopores by directly pyrolyzing Fe-ZIF-8 covered with a controllable melamine layer. It is demonstrated that the introduction of melamine in the precursor plays a key role in constructing various carbonized products with controllable morphology, porosity, and components. With an optimal mass ratio 1:1 of melamine to Fe-ZIF-8, the resultant Fe@MNC-1 exhibits excellent ORR activity and stability, which exceeds 20 wt % commercial Pt/C catalyst (with a half-wave potential of 0.88 V vs 0.85 V) in an alkaline electrolyte and is even comparable to the commercial Pt/C catalyst (with a half-wave potential of 0.78 V vs 0.80 V) in an acidic electrolyte. To the best of our knowledge, Fe@MNC-1 can be ranked among the best nonprecious metal electrocatalysts for ORR in both alkaline and acidic media. The present synthetic strategy may provide a new opportunity for the design and construction of metal–organic framework-derived nanomaterials with rational composition and a desired porous structure to boost their electrocatalytic performance.
研究领域:
材料科学
·
电化学
·
催化
·
纳米材料
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）