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17 results on '"Ze, Huajie"'

10. High-Efficiency Boiling Heat Transfer Interfaces Composed of Electroplated Copper Nanocone Cores and Low-Thermal-Conductivity Nickel Nanocone Coverings

Author

Shihan Chen, Ze Huajie, Feifei Wu, and Xuefeng Gao

Subjects
0303 health sciences, Materials science, Critical heat flux, Thermal resistance, chemistry.chemical_element, 02 engineering and technology, Heat transfer coefficient, 021001 nanoscience & nanotechnology, Copper, Superheating, 03 medical and health sciences, Thermal conductivity, chemistry, Heat transfer, General Materials Science, Composite material, 0210 nano-technology, Nucleate boiling, 030304 developmental biology
Abstract

We demonstrate that copper-based super-thin high-efficiency boiling heat transfer (BHT) interfaces can be obtained via electroplating hierarchical nickel nanocone coverings on the surface of copper nanocone cores. By regulating surface morphologies, wettability, and mass and heat transfer properties of hierarchical structures, we reveal the regulation rules of their performance. Based on this, we obtain the optimized BHT interfaces with a thickness of only 6.4 μm, which shows 228% enhancement in the maximal heat transfer coefficient, 71% enhancement in the critical heat flux, and 68% decrease in the superheat for the onset of nucleate boiling, as compared to the flat copper surface. Our studies clearly indicate that, although the in situ growth of nickel nanocones can unavoidably increase the interface thermal resistance of hierarchical structures, its optimization can still enhance BHT performance. This may be ascribed to the coupling of several interface effects such as more heat transfer area, more nucleation sites, smaller bubble departure sizes, and stronger liquid supply ability caused by hierarchical structures. Our work opens up a new avenue for the development of copper-based super-thin high-efficiency BHT interfaces, which would help enhance the efficiency of energy utilization and heat dissipation of various thermal devices.

Published
2020

15. Molecular Insight of the Critical Role of Ni in Pt-Based Nanocatalysts for Improving the Oxygen Reduction Reaction Probed Using an In SituSERS Borrowing Strategy

Author

Ze, Huajie, Chen, Xing, Wang, Xiao-Ting, Wang, Yao-Hui, Chen, Qing-Qi, Lin, Jia-Sheng, Zhang, Yue-Jiao, Zhang, Xia-Guang, Tian, Zhong-Qun, and Li, Jian-Feng

Abstract

PtNi alloy catalysts have excellent catalytic activity and are considered some of the most promising electrocatalysts capable of replacing pure Pt for the oxygen reduction reaction (ORR). For PtNi alloys, Ni-doping can improve performance by changing the electronic and structural properties of the catalyst surface and its interaction with reaction intermediates. However, to date there is no direct spectral evidence detecting or identifying the effect of Ni on the ORR in PtNi alloy catalysts. Herein, we introduce a surface-enhanced Raman spectroscopic (SERS) “borrowing” strategy for investigating ORR processes catalyzed by Au@PtNi nanoparticles (NPs). The bond vibration of adsorbed peroxide intermediate species (*OOH) was obtained, and the effect of Ni on the interaction between surface Pt and *OOH was studied by varying the Ni content in the alloy. The frequency of the *OOH spectral band has an obvious red-shift with increasing Ni content. Combined with density functional theory (DFT) calculations, we show that Ni-doping can optimize *OOH surface binding on the Pt surface, achieving more efficient electron transfer, thus improving the ORR rate. Notably, these results evidence the SERS borrowing strategy as an effective technique for in situobservations of catalytic processes.

Published
2021
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16. In Situ Probing the Structure Change and Interaction of Interfacial Water and Hydroxyl Intermediates on Ni(OH) 2 Surface over Water Splitting.

Author

Ze H, Yang ZL, Li ML, Zhang XG, A YL, Zheng QN, Wang YH, Tian JH, Zhang YJ, and Li JF

Abstract

There is growing acknowledgment that the properties of the electrochemical interfaces play an increasingly pivotal role in improving the performance of the hydrogen evolution reaction (HER). Here, we present, for the first time, direct dynamic spectral evidence illustrating the impact of the interaction between interfacial water molecules and adsorbed hydroxyl species (OH ad ) on the HER properties of Ni(OH) 2 using Au/core-Ni(OH) 2 /shell nanoparticle-enhanced Raman spectroscopy. Notably, our findings highlight that the interaction between OH ad and interfacial water molecules promotes the formation of weakly hydrogen-bonded water, fostering an environment conducive to improving the HER performance. Furthermore, the participation of OH ad in the reaction is substantiated by the observed deprotonation step of Au@2 nm Ni(OH) 2 during the HER process. This phenomenon is corroborated by the phase transition of Ni(OH) 2 to NiO, as verified through Raman and X-ray photoelectron spectroscopy. The significant redshift in the OH-stretching frequency of water molecules during the phase transition confirms that surface OH ad disrupts the hydrogen-bond network of interfacial water molecules. Through manipulation of the shell thickness of Au@Ni(OH) 2 , we additionally validate the interaction between OH ad and interfacial water molecules. In summary, our insights emphasize the potential of electrochemical interfacial engineering as a potent approach to enhance electrocatalytic performance.

Published
2024
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17. Unmasking the Critical Role of the Ordering Degree of Bimetallic Nanocatalysts on Oxygen Reduction Reaction by In Situ Raman Spectroscopy.

Author

Chen HQ, Ze H, Yue MF, Wei DY, A YL, Wu YF, Dong JC, Zhang YJ, Zhang H, Tian ZQ, and Li JF

Abstract

Precise control and accurate understanding of the ordering degree of bimetallic nanocatalysts (BNs) are challenging yet crucial to acquire advanced materials for the oxygen reduction reaction (ORR). AuCu BNs with various ordering degrees were synthesized to evaluate the influence of ordering degree on the ORR at a molecular level using in situ Raman spectroscopy. The activity of AuCu BNs was improved by over 2 times after a disorder-to-order transition, making the performance of highly ordered AuCu BNs exceed that of benchmark Pt/C. Direct Raman spectroscopic evidence of key intermediate (*OH) demonstrates that the active site is the combination site of Au and Cu. Moreover, two distinct *OH species are observed on the ordered and disordered structure, and the ordered site is more beneficial for ORR due to its lower affinity to *OH. This work deepens the understanding on the important role of ordering degree on BNs and enables the design of improved catalysts., (© 2022 Wiley-VCH GmbH.)

Published
2022
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