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您的检索式：作者名="David A.Cullen"
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| 1 | Electrochemically Grown Ultrathin Platinum Nanosheet Electrodes with Ultralow Loadings for Energy-Saving and Industrial-Level Hydrogen Evolution显示文摘Nanostructured catalyst-integrated electrodes with remarkably reduced catalyst loadings,high catalyst utilization and facile fabrication are urgently needed to enable cost-effective,green hydrogen production via proton exchange membrane electrolyzer cells(PEMECs).Herein,benefitting from a thin seeding layer,bottom-up grown ultrathin Pt nanosheets(Pt-NSs)were first deposited on thin Ti substrates for PEMECs via a fast,template-and surfactant-free electrochemical growth process at room temperature,showing highly uniform Pt surface coverage with ultralow loadings and vertically well-aligned nanosheet morphologies.Combined with an anode-only Nafion 117 catalyst-coated membrane(CCM),the Pt-NS electrode with an ultralow loading of 0.015 mgPt cm−2 demonstrates superior cell performance to the commercial CCM(3.0 mgPt cm^(−2)),achieving 99.5%catalyst savings and more than 237-fold higher catalyst utilization.The remarkable performance with high catalyst utilization is mainly due to the vertically well-aligned ultrathin nanosheets with good surface coverage exposing abundant active sites for the electrochemical reaction.Overall,this study not only paves a new way for optimizing the catalyst uniformity and surface coverage with ultralow loadings but also provides new insights into nanostructured electrode design and facile fabrication for highly efficient and low-cost PEMECs and other energy storage/conversion devices. | Lei Ding Zhiqiang Xie Shule Yu Weitian Wang Alexander Y.Terekhov Brian K.Canfield Christopher B.Capuano Alex Keane Kathy Ayers David A.Cullen Feng-Yuan Zhang | 2023 | Nano-Micro Letters2023，15，9： | 1 |
| 2 | Characterizing and modeling the precipitation of Mg-rich phases in Al 5xxx alloys aged at low temperatures显示文摘Al 5083 alloys(5.25 at.% Mg) of different tempers(H131 and H116) were aged at low temperatures(50and 70?C) for 41 months. Scanning transmission electron microscopy(STEM), energy-dispersive X-ray spectroscopy(EDS), and atom probe tomography(APT) were applied to characterize precipitates formed in the sensitized samples. Experimental results revealed that the size of Mg-rich precipitates increased with aging time at 70?C for both alloys. APT results showed that Mg-rich precipitates of different Mg concentrations and morphologies formed in Al matrix and on the interface of Al matrix/pre-existing particles. In addition, a model based on local equilibrium of chemical potential and multi-class precipitates number evolution was adopted to predict the multiphase precipitation process in the Al-Mg binary system. The overall trend of precipitate radius and number density predicted by the model matched well with the experimental results. Moreover, modeling results revealed that nucleation and coarsening occurred faster in Al 5083 H131 than in Al 5083 H116 when aged at same temperature. The high density of dislocations and the pipe diffusion mechanism of dislocations can be used to explain such behavior. | Gaosong Yi Weizhi Zeng Jonathan D.Poplawsky David A.Cullen Zhifen Wangd Michael L.Free | 2017 | Journal of Materials Science & Technology2017，33，9： | 1 |
| 3 | Elucidating the impact of the ionomer equivalent weight on a platinum group metal-free PEMFC cathode via oxygen limiting current显示文摘Leveraging the interactions between ionomer and catalyst can increase the performance of proton exchangemembrane fuel cells.The impacts of the equivalent weight(EW)of perfluorosulfonic acid-based ionomers on the platinum group metal-free electrode structure and fuel cell performance have not been fully explored.Four membrane electrode assemblies(MEAs)were prepared by using a commercial Fe-N-C catalyst,two perfluorosulfonic acid ionomers with different EWs,that is,Aquivion 720(A720)and Nafion 1100(N1100),and two ionomer-tocatalyst(I/C)ratios.The four MEAswere characterized to understand the impact of the ionomer EW and content on the capacitance,proton conductivity,and mass transport on the cathode.The mass transport resistance was measured for the first time using a new oxygen reduction reaction limiting current method enabling to couple the effects of oxygen diffusion with liquid water generation.Low EW ionomer combined with a moderate I/C results in improved performance due to its enhanced proton conductivity.However,when used at high I/C,it can cause severewater flooding at high current density due to the enhanced liquid water uptake,especially at high relative humidity,resulting in lower catalyst utilization and higher mass transport resistance. | HaoWang Luigi Osmieri Haoran Yu Michael J.Zachman Jae Hyung Park Nancy N.Kariuki Firat C.Cetinbas Sunilkumar Khandavalli Scott Mauger Deborah J.Myers David A.Cullen Kenneth C.Neyerlin | 2023 | SusMat2023，3，1： | 0 |
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