Article
Thermodynamics
Jinhu Li, Wei Lu, Jinliang Li, Yongliang Yang, Zenghua Li
Summary: The room temperature oxidation of active sites is considered as the initial heat source for coal self-heating, but the specific microscopic reactions involved in coal oxidation are still not well understood. Therefore, the interconversions between oxygen-functional groups and active sites were investigated. The low-temperature oxidation combined with low-temperature pyrolysis process was used to measure the macroscopic gas concentrations and determine the microscopic content of free radicals and oxygen-containing functional groups. The results revealed that alkyl radicals are the active sites that can transform into oxygen-functional groups during oxidation, leading to heat accumulation and uncontrolled spontaneous combustion.
Article
Chemistry, Multidisciplinary
Xiaoyang Cheng, Xiaotian Jiang, Shuhu Yin, Lifei Ji, Yani Yan, Guang Li, Rui Huang, Chongtai Wang, Honggang Liao, Yanxia Jiang, Shigang Sun
Summary: In order to achieve Fe-N-C materials with both high activity and durability in proton exchange membrane fuel cells, it is necessary to overcome the attack of free radicals on Fe-N-4 sites. In this study, CeO2 nanoparticles were anchored as radicals scavengers adjacent to the Fe-N-4 sites to effectively eliminate radicals at the source and mitigate degradation. The CeO2 scavengers in the Fe-NC/Sca(ad-CeO2) achieved about 80% elimination of the radicals generated at the Fe-N-4 sites. A fuel cell prepared with the Fe-NC/Sca(ad-CeO2) showed a smaller peak power density decay after 30,000 cycles, reducing the decay from 69% to 28% compared to Fe-NCPhen.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Review
Chemistry, Multidisciplinary
Christopher Uyeda, Conner M. Farley
Summary: Multinuclear catalysts show unique abilities to cooperatively engage substrates, while binuclear catalysts provide new electronic configurations and covalent bonding to effectively address challenges not easily solved by single-metal systems. Novel ligands can stabilize metal-metal bonds, activate strong bonds, and have significant implications in catalytic reactions.
ACCOUNTS OF CHEMICAL RESEARCH
(2021)
Review
Nanoscience & Nanotechnology
Jinyu Zhao, Jie Lian, Zhenxin Zhao, Xiaomin Wang, Jiujun Zhang
Summary: Electrocatalytic oxygen reduction reaction (ORR) is crucial for electrochemical energy technologies. However, the identification of ORR active sites and the elucidation of ORR mechanisms are challenging due to the complex dynamic evolution of catalysts and intermediates. In-situ characterization techniques are necessary for real-time monitoring of catalyst structure, intermediate behavior, and product evolution. This review highlights the advances in using various in-situ techniques to study catalytic processes, including catalyst structure evolutions, intermediate adsorption/desorption behavior, and product nucleation and reconstruction. Challenges and prospects of in-situ techniques for future catalysts research in the ORR process are also discussed.
NANO-MICRO LETTERS
(2023)
Article
Environmental Sciences
Yanhui Sun, Lin Liu, Ming Li, Xiaoxiao Chen, Fei Xu
Summary: Vanillin and vanillic acid are two lignin pyrolysis products generated by biomass combustion. The gas-phase oxidation mechanisms of vanillin and vanillic acid initiated by OH/NO3 radicals were investigated using density functional theory. The primary reactions involve OH/NO3 addition and H-atom abstraction, leading to the formation of various oxidation products. The total rate constants and atmospheric lifetimes of the oxidation processes were calculated, providing valuable information for further experimental research.
Review
Materials Science, Multidisciplinary
Hainan Sun, Xiaomin Xu, Hyunseung Kim, Zongping Shao, Woochul Jung
Summary: This review presents the latest progress in the identification of unconventional active sites in electrochemical water splitting. The use of advanced characterization techniques and theoretical calculations has revealed novel and unusual active sites, providing valuable guidance for the design of advanced electrocatalysts.
Article
Chemistry, Physical
Zhipeng Yu, Chaowei Si, Alec P. LaGrow, Zhixin Tai, Wolfgang A. Caliebe, Akhil Tayal, Maria J. Sampaio, Juliana P. S. Sousa, Isilda Amorim, Ana Araujo, Lijian Meng, Joaquim L. Faria, Junyuan Xu, Bo Li, Lifeng Liu
Summary: This study reports a bimetallic iridium-iron diatomic catalyst (IrFe-N-C) that exhibits excellent performance in oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) and is used in zinc-air batteries.
Article
Engineering, Chemical
Fei Wang, Chunxue Wang, Ke Zhao, Yulong Shan, Yixing Ma, Chi Wang, Zhilin Li, Xin Sun, Kai Li, Hong He, Ping Ning
Summary: Ce-based catalyst is an important catalyst for NH3-SCR reaction, with Ce3+ playing a crucial role. However, the specific atomic sites for Ce anchoring and the chemical mechanism of Ce3+ formation in CeO2 are not fully understood. This study reveals that UiO-66 has abundant hydroxyl groups on its surface, which serve as anchoring sites for Ce. Additionally, the introduction of highly dispersed acidic sites (WO3) around CeO2 enhances the catalytic activity and stability by tightly coupling the redox and acidic sites.
SEPARATION AND PURIFICATION TECHNOLOGY
(2022)
Review
Chemistry, Physical
Dongge Wang, Juanxia Wu, Liying Jiao, Liming Xie
Summary: The rational design of efficient, low-cost, and durable catalysts is crucial for industrial applications of electrocatalytic hydrogen production. Identifying the catalytic active sites in real-time for the hydrogen evolution reaction (HER) is a key step towards designing high-performance catalysts, but it poses great challenges. This review summarizes recent advances in the in situ investigation of active sites on low-dimensional catalysts for HER and highlights various characterization techniques used for this purpose. Future opportunities in this emerging field are also discussed, along with the current technical limitations.
Article
Chemistry, Multidisciplinary
Wenzhong Huang, Jiantao Li, Xiaobin Liao, Ruihu Lu, Chaohong Ling, Xiong Liu, Jiashen Meng, Longbing Qu, Mengting Lin, Xufeng Hong, Xunbiao Zhou, Shanlin Liu, Yan Zhao, Liang Zhou, Liqiang Mai
Summary: This study proposes a feasible ligand modulation strategy to boost the oxygen evolution reaction (OER) catalytic activity of cobalt-iron oxyhydroxide ((Fe,Co)OOH). By reducing the orbital overlap between the Fe/Co 3d and O 2p, the adsorption to oxygen-containing intermediates is weakened, which facilitates the O-2 desorption. The ligand-modulated (Fe,Co)OOH exhibits excellent OER performance with low overpotentials and high durability.
ADVANCED MATERIALS
(2022)
Review
Chemistry, Physical
Zibo Zhai, Wei Yan, Li Dong, Shuqi Deng, David P. Wilkinson, Xiaomin Wang, Lei Zhang, Jiujun Zhang
Summary: This paper reviews the recent progress in MOF-derived electrocatalysts, focusing on the characterization of catalytically active sites, functional mechanisms, and performance validation of various reactions. The synthesis methods, including alloy and composite formation, edge-defect/oxygen vacancy engineering, as well as advanced characterization techniques and theoretical calculations are discussed. The paper also analyzes technical challenges and proposes further research directions for the development of practical MOF-derived electrocatalysts in the future.
JOURNAL OF MATERIALS CHEMISTRY A
(2021)
Article
Chemistry, Multidisciplinary
Guangchao Li, Christopher Foo, Xianfeng Yi, Wei Chen, Pu Zhao, Pan Gao, Tatchamapan Yoskamtorn, Yao Xiao, Sarah Day, Chiu C. Tang, Guangjin Hou, Anmin Zheng, Shik Chi Edman Tsang
Summary: This study provides the first direct experimental observation of induced active sites in zeolites, which contradicts traditional views. Evidence shows that under the action of strong polar adsorbates, typical acid sites in pristine zeolites can transform into new induced structures.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Physical
Chenxi Hu, Huihui Jin, Bingshuai Liu, Lvhan Liang, Zhe Wang, Ding Chen, Daping He, Shichun Mu
Summary: The introduction of Vitamin C can effectively suppress the free metal ions on the surface of metal organic frameworks, increase Fe-N4 active sites, and enhance catalytic performance, demonstrating the universality of this strategy.
Article
Chemistry, Physical
Qingmeng Gan, Ning Qin, Shuai Gu, Zhenyu Wang, Zhiqiang Li, Kemeng Liao, Kaili Zhang, Li Lu, Zhenghe Xu, Zhouguang Lu
Summary: By introducing a high concentration of pyridine N and constructing a 3D hard carbon with a multistage pore structure, extra radical sites were provided to improve the electrochemical performance of hard carbon as an anode material for sodium-ion batteries.
Article
Engineering, Environmental
Xiaoxi Guo, Bo Hu, Ke Wang, Huanhuan Wang, Bolan Li, Mai Guo, Yun Tian, Ruixue Zhang, Shishuai Shi, Yifan Han
Summary: Cu-Co bimetallic catalysts exhibit excellent performance in Fenton-like reaction for metronidazole degradation. The active species in this reaction is identified as Cu+ on the surface of Co3O4, and its concentration plays a significant role. The synergistic interaction between Cu and Co enhances the dissociation of H2O2 and accelerates the redox process, resulting in faster electron transfer rate and improved reaction performance.
CHEMICAL ENGINEERING JOURNAL
(2022)
