ACS Applied Energy Materials
·
2023
·
IF 6.4
Siqi Fang,Guoliang Liu,Minghai Li,Haining Zhang,Jun Yu,Fangfang Zhang,Mu Pan,Haolin Tang
Reducing the local oxygen transport resistance in the cathode catalyst layer of the proton exchange membrane fuel cell (PEMFC) is crucial for the improvement of cell performance, particularly for low platinum loading. In this work, we report that the performance of PEMFC can be significantly improved by replacing Nafion with a highly oxygen-permeable perfluoronated ionomer containing dioxole segments on the backbone as both proton conductor and catalyst binder in the cathode catalyst layer, as evidenced by the increased peak power density of 100 mW cm–2. Molecular dynamics simulation results reveal that the synthesized ionomer has higher diffusion coefficient and higher oxygen solubility compared with Nafion. Benefiting from the high oxygen permeability, both the specific activity and mass specific activity of a Pt/C catalyst using the designed ionomer as catalyst binder for the oxygen reduction reaction are three times higher than those of a catalyst using Nafion as catalyst binder. The results demonstrate that the rational design of highly oxygen-permeable ionomers applied in the catalyst layer could be an effective strategy for a high-performance PEMFC with low platinum loading.
研究领域:
能源科学
·
材料化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Hui Ye,Yixuan Feng,Pengkai Shan,Bin Qian,Lin Ge,Han Chen,Yifeng Zheng
Reversible solid oxide cells (RSOCs) have attracted considerable interest due to their efficient energy conversion. However, the low catalytic activity of air electrodes limits the application of RSOCs. Bi 0.5 Sr 0.5 Fe 0.9 Ta 0.1 O 3-δ developed in our previous work exhibits a comparatively desirable performance and is expected to be further optimized. Herein, a novel strategy of anionic F and cationic Ta co-doped Bi 0.5 Sr 0.5 Fe 0.9 Ta 0.1 O 3-δ-x F x (x = 0, 0.05, 0.10, 0.15, denoted as, BSFTF0, BSFTF5, BSFTF10, BSFTF15) materials are obtained to enhance the oxygen transport property of Bi 0.5 Sr 0.5 FeO 3-δ for RSOCs. The polarization resistance (Rp) of BSFTF10 (0.017 Ω cm 2 ) decreases by 66 % compared with that of BSFTF0 (0.051 Ω cm 2 ) at 800 °C. In fuel cell mode, the single cell with BSTF10 reaches the maximum power density of 908 mW cm −2 , which is approximately 72 % higher than the only Ta-doped BSFTF0 (527 mW cm −2 ) at 800 °C. In electrolysis mode, the single cell with BSFTF10 exhibits a high electrolysis current density of 1679 mA cm −2 , indicating an approximately 90 % increase compared to that of BSFTF0 at 800 °C and 1.5 V with 70 % CO 2 -30 % CO feed gas. The bulk chemical diffusion (D chem ) of BSFTF10 is up to 5.12 × 10 −4 cm 2 s −1 , which is 4.3 times higher than that of BSFTF0. The superior oxygen transport property of BSFTF10 is attributed to the high electronegativity of F − (4.0) and low electronegativity of Ta 5+ (1.8), which may weaken the chemical bonding between B-site ions and O 2− , generating more oxygen vacancies and accelerating the rate of oxygen transfer. The results indicate that F and Ta co-doping is an effective strategy to develop a highly catalytically active air electrode for RSOCs featuring oxygen transport properties.
研究领域:
材料科学
·
能源工程
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2016
·
IF 3.205
Shengli Pang,Wenzhi Wang,Tao Chen,Yonggang Wang,Kaijie Xu,Xiangqian Shen,Xiaoming Xi,Jiwei Fan
An understanding of the relationships between the processing, compositions , and properties of perovskites is vitally important in the search for high performance cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). In this work, the properties of PrBa 1−x Co 2 O 5+δ (x = 0.00–0.10) double perovskites were modified by introducing K during synthesis, and their performances as the cathode materials for IT-SOFCs were then characterized. The addition of K resulted in a greater cation deficiency in the double perovskites, improving bulk oxygen transport. However, K addition also markedly decreased the Co ion content on the perovskites' surfaces, which significantly deteriorated the perovskites’ electrochemical performances related to the surface exchange of oxygen.
研究领域:
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2025
·
IF 7.5
Lijun Qin,Dan Li,Yiyun Hu,Qiuhong Wang,Ting Gong,Jian Zhang,Hao Feng
Boron has emerged as a highly attractive high-energy fuel/additive for multi-scenario applications including powder ramjet engines and rocket propellants, owing to its exceptional calorific value. However, the inherent surface oxide layer impedes oxygen diffusion during combustion, resulting in ignition difficulties and incomplete combustion. This study provides a methodology for constructing titanium oxide activation layers on boron particles via atomic layer deposition (ALD), with systematic investigation of how coating thickness (precisely controlled at 0.046 nm/cycle) influences thermal oxidation behavior and ignition characteristics through multi-technique characterizations. It is demonstrated that complete and uniform encapsulation of boron particles was achieved by TiO 2 nano-coatings. Compared to pristine boron, ALD TiO 2 -activated specimens exhibit significant performance enhancements including reduced oxidation temperature (ΔTp = 133 °C), shortened laser ignition delay (32 % reduction), minimized ignition energy of dust clouds (over 90 % decrease), and accelerated flame propagation velocity in dust clouds (one order of magnitude increase). Mechanistic analysis reveals that these improvements originate from a synergistic oxygen transport mechanism between oxygen vacancies in TiO 2 and B 2 O 3 -TiO 2 solid-solution interfaces. The uniformly distributed TiO 2 surface modification layer establishes sustainable oxygen transport channels through surface vacancy defects, maintaining stable oxygen concentration at reaction interfaces and thereby accelerating boron oxidation kinetics. This work provides both theoretical foundations and practical engineering solutions for overcoming critical bottlenecks in boron-based energy applications.
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED MATERIALS
·
2023
·Vol. 35
·期 31
·2300624
·
IF 29.4
Yi Luo,Ke Li,Yongting Chen,Junzong Feng,Lukai Wang,Yonggang Jiang,Liangjun Li,Gang Yu,Jian Feng
Achieving high catalytic performance through the lowest possible content of platinum (Pt) is the key to cost reduction of proton-exchange-membrane fuel cells (PEMFCs). However, lowering the Pt loading in PEMFCs leads to the high mass-transport resistance of oxygen originating from the limited active sites, and causes less stability of the catalysts due to Pt size growth after long-time operation. Herein, Pt–metal/metal–N–C aerogel catalysts are designed that substantially reduce oxygen-related mass transport resistance and have long-term durability. The tailoring of the Fe–N–C aerogel support with hierarchical and interconnecting pores enable a low local oxygen transport resistance (0.18 s cm −1 ) for PEMFCs with ultralow Pt loading (50 ± 5 µg Pt cm − 2 ). Chemical confinement of Fe─N sites ensures high stability of the loaded-Pt both in the processes of synthesis up to 1000 °C and practical application in PEMFCs. The ultralow Pt PEMFC displays a low voltage loss of 8 mV at 0.80 A cm − 2 and unchanged electrochemical surface area after 60 000 cycles of accelerated durability testing. The allying of the hierarchical pores, the aerogel, and the single atoms can fully reflect their structural advantages and expand the understanding for the synthesis of advanced fuel cell PEMFCs catalysts.
研究领域:
材料科学
·
能源工程
·
化学工程
✓ 已验证
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Huiyuan Li,Jiabin You,Xiaojing Cheng,Xiaohui Yan,Shuiyun Shen,Junliang Zhang
Pt alloy electrocatalysts (e.g., Pt 3 Co) for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) have attracted a great deal of interest from worldwide researchers in past decades, due to the excellent ORR activity and cost-effective properties. However, the long period operation would yield sever dissolution of the non-precious metal which effects the ionomer microstructure, thus leading to significantly decreased ORR activity of catalyst and aggravated of the oxygen transport resistance in cathode catalyst layers (CCLs), especially the local oxygen transport resistance caused by the ultrathin ionomer film covering on catalyst surface. Herein, in this paper, the effects of Co 2+ contamination on structure of ionomer films and the corresponding local oxygen transport behavior in CCLs are explored via physicochemical characterizations and molecular dynamics (MD) simulations, limiting current method, as well as fuel cell performance measurement. It is found that Co 2+ contamination reduces water content and increases the modulus of the ultrathin ionomer film, while reducing the distance between the sulfonic acid groups and increasing the aggregation size of the ionomer, which is related to the volume of hydrophilic domains. Additionally, the electrochemical measurement results demonstrate that as the degree of Co 2+ contamination increases from 0 to 85 %, the local oxygen transport resistance increases from 27.74 s cm −1 to 42.43 s cm −1 , and the peak power density of fuel cell reduces from 510 mW cm −2 to 453 mW cm −2 . The reason behind lies on that contaminated Co 2+ tends to connect with sulfonate, then suppress the ionomer mobility and dislocate the local oxygen transport channels.
研究领域:
电化学
·
材料科学
·
能源工程
·
催化化学
·
高分子科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2023
·
IF 16.5
Jiachen Sun,Sai Chen,Donglong Fu,Wei Wang,Xianhui Wang,Guodong Sun,Chunlei Pei,Zhi-Jian Zhao,Jinlong Gong
The bulk oxygen transfer and surface reaction as important parts of the chemical looping-related process are crucial for the rational design of new redox catalysts. This paper describes an experimental study on the effect of bulk oxygen transfer and surface reaction in Ce 1– x x O 2 supported VO x redox catalysts for the chemical looping oxidative propane dehydrogenation reaction. It was found that the introduction of Zr dictates the reaction performance of the redox catalyst by modulating the bulk oxygen transfer and surface reaction. The kinetic study reveals that the instantaneous reduction rate of the redox catalysts is determined by the H-abstraction step in the surface reaction. The introduction of Zr can reduce the activation energy of the H-abstraction step, which leads to the enhancement of the instantaneous reduction rate. Meanwhile, the oxygen supply capacity of the cerium oxide is increased by Zr, allowing the surface reaction to proceed over longer durations. Furthermore, the reaction model derived from the kinetics study is validated using a number of (quasi) in situ techniques. This study provides fundamental insights into the role of bulk oxygen transfer and surface reaction in chemical looping or related process.
研究领域:
催化
·
化学工程
·
材料科学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）