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172 results on '"Han, Aijuan"'

8. A Vacuum Vapor Deposition Strategy to Fe Single‐Atom Catalysts with Densely Active Sites for High‐Performance Zn–Air Battery.

Author

Yang, Xiang, Zhu, Baohui, Gao, Zhiyang, Yang, Can, Zhou, Jingbo, Han, Aijuan, and Liu, Junfeng

Subjects
IRON catalysts, VAPOR-plating, VACUUM deposition, OXYGEN reduction, CHARGE transfer
Abstract

Iron single‐atom catalysts (SACs) have garnered increasing attention as highly efficient catalysts for the oxygen reduction reaction (ORR), yet their performance in practical devices remains suboptimal due to the low density of accessible active sites. Anchoring iron single atoms on 2D support is a promising way to increase the accessible active sites but remains difficult attributing to the high aggregation tendency of iron atoms on the 2D support. Herein, a vacuum vapor deposition strategy is presented to fabricate an iron SAC supported on ultrathin N‐doped carbon nanosheets with densely active sites (FeSAs‐UNCNS). Experimental analyses confirm that the FeSAs‐UNCNS achieves densely accessible active sites (1.11 × 1020 sites g−1) in the configuration of Fe─N4O. Consequently, the half‐wave potential of FeSAs‐UNCNS in 0.1 m KOH reaches a remarkable value of 0.951 V versus RHE. Moreover, when employed as the cathode of various kinds of Zn–air batteries, FeSAs‐UNCNS exhibits boosting performances by achieving a maximum power density of 306 mW cm−2 and long cycle life (>180 h) at room temperature, surpassing both Pt/C and reported SACs. Further investigations reveal that FeSAs‐UNCNS facilitates the mass and charge transfer during catalysis and the atomic configuration favors the desorption of *OH kinetically. [ABSTRACT FROM AUTHOR]

Published
2024
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27. Ni single‐atom arrays as self‐supported electrocatalysts for CO2RR.

Author

Ma, Zhanshuai, Zhang, Tianyu, Lin, Lili, Han, Aijuan, and Liu, Junfeng

Subjects
ELECTROCATALYSTS, GREENHOUSE effect, ENERGY shortages, IONOMERS, OXYGEN reduction, DOPING agents (Chemistry), ENERGY consumption, NICKEL catalysts, DIFFUSION
Abstract

Developing highly active, selective, and stable electrocatalysts for the CO2 reduction reaction (CO2RR) is essential to relieve the greenhouse effect and the energy crisis. Traditional catalytic electrodes require ionomer binders, which inevitably impose undesired high CO2 transport resistance and block the active sites. Herein, Ni single atoms anchored on nitrogen‐doped carbon nanoarrays (denoted as Ni‐SAC‐NA) were developed as the electrode without additional ionomers for efficient CO2RR. The unique nanoarray structure provided a higher specific surface area, more exposed active sites, and enhanced electron/mass transport due to its short diffusion pathway and ionomer‐free nature. As a result, the Ni‐SAC‐NA electrode exhibited enhanced activity of CO2RR and selectivity towards CO with Faradaic efficiency of 96.7%, turnover frequency of 27,504 h−1, and cathodic energy efficiencies of 54.9% at −0.88 V (vs. RHE). Our findings provide a rational design strategy for CO2RR electrocatalysts by constructing ionomer‐free electrodes. [ABSTRACT FROM AUTHOR]

Published
2023
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33. Oxygen Reduction Reaction: MnN 4 Oxygen Reduction Electrocatalyst: Operando Investigation of Active Sites and High Performance in Zinc–Air Battery (Adv. Energy Mater. 6/2021)

Author

Han, Xu, primary, Zhang, Tianyu, additional, Chen, Wenxing, additional, Dong, Bo, additional, Meng, Ge, additional, Zheng, Lirong, additional, Yang, Can, additional, Sun, Xiaoming, additional, Zhuang, Zhongbin, additional, Wang, Dingsheng, additional, Han, Aijuan, additional, and Liu, Junfeng, additional

Published
2021
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41. Microenvironment Engineering of Ru Single‐Atom Catalysts by Regulating the Cation Vacancies in NiFe‐Layered Double Hydroxides.

Author

Jin, Jing, Han, Xu, Fang, Yingyan, Zhang, Zedong, Li, Yaping, Zhang, Tianyu, Han, Aijuan, and Liu, Junfeng

Subjects
ELECTRON configuration, ALCOHOL oxidation, CATALYSTS, BENZYL alcohol, HYDROXIDES, CATALYTIC activity, RUTHENIUM catalysts
Abstract

Single‐atom catalysts (SACs) with rationally designed microenvironments (defined as coordination environments and electronic configurations) show superior catalytic activity, selectivity, and stability in a majority of reactions. However, the construction of isolated SACs with definite microenvironments to understand the microenvironment–activity relationship is still challenging. Herein, a facile strategy is developed to construct a series of Ru SACs with tunable geometric and electronic structures by employing NiFe‐layered double hydroxides (LDH) with different cation vacancies (MII or MIII) as supports. Detailed spectroscopic characterizations and theoretical calculations reveal that the Ru‐O coordination environments and electronic configurations of single‐atomic Ru can be easily tailored by the vacancy regulation. As a result, isolated Ru atoms anchored by MIII vacancies (denoted as Ru1/LDH‐VIII) with Ru‐O‐Ni coordination environments facilitate the desorption of benzaldehyde, thus leading to higher efficiency of benzyl alcohol oxidation with a superior turnover frequency of 1331 h−1. [ABSTRACT FROM AUTHOR]

Published
2022
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48. Boosting ORR performance by single atomic divacancy Zn–N3C–C8sites on ultrathin N-doped carbon nanosheets

Author

Zhang, Tianyu, Wang, Fanping, Yang, Can, Han, Xu, Liang, Chen, Zhang, Zedong, Li, Yaping, Han, Aijuan, Liu, Junfeng, and Liu, Bin

Abstract

Single-atom catalysts (SACs) show great promise to improve the performance of catalysis because of their spatially isolated single-atom sites with unique electronic properties. Herein, we construct single Zn atoms anchored on ultrathin two-dimensional (2D) N-doped carbon nanosheets (Zn–SAs/UNCNS) as an efficient electrocatalyst for oxygen reduction reaction (ORR). The microenvironment of Zn–SAs/UNCNS with super ORR intrinsic activity was identified as the divacancy Zn–N3C–C8by both experiments and theoretical simulations. Density functional theory (DFT) calculations reveal that the divacancy Zn–N3C–C8sites exhibit near-Fermi electronic states distinct from those of graphene-enclosed Zn–N4–C10and divacancy trans-Zn–N2C2–C8sites, which greatly facilitate the ORR process. Furthermore, compared with 3D architecture, the single atomic divacancy Zn–N3C–C8sites anchored on ultrathin 2D carbon nanosheets show more active site exposure and fast electron transport, which collectively boost the ORR performance, showing a high half-wave potential of 0.91 V versus reversible hydrogen electrode [RHE] and a super turnover frequency (4.99 e−site−1s−1).

Published
2022
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