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| 1 | Electropolishing of titanium alloy under hydrodynamic mode显示文摘Titanium(Ti) alloys are widely used in aerospace industry due to the low density and high corrosion resistance. However, machining and polishing remain great challenges because of the hardness and chemical stability. With a home-made electrochemical machining workstation, cyclic voltammetry is performed at a wide potential range of [0 V, 20 V] to record the details of passivation and depassivation processes under a hydrodynamic mode. The results show that the thickness of viscous layer formed on the alloy surface plays a crucial effect on the electropolishing quality. The technical parameters, including the mechanical motion rate, polishing time and electrode gap, are optimized to achieve a surface roughness less than 1.9 nm, which shows a prospective application in the electrochemical machining of Ti and it alloys. | Pei Huang Junhui Lai Lianhuan Han Fang-Zu Yang Li-Min Jiang Jian-Jia Su Zhao-Wu Tian Zhong-Qun Tian Dongping Zhan | 2016 | Science China Chemistry2016，59，11： | 3 |
| 2 | Nanofabrication of the gold scanning probe for the STM-SECM coupling system with nanoscale spatial resolution显示文摘Scanning probe is the key issue for the electrochemical scanning probe techniques(EC-SPM) such as EC-scanning tunnel microscopy(STM), EC-atomic force microscopy(AFM) and scanning electrochemical microscopy(SECM), especially the insulative encapsulation of the nanoelectrode probe for both positioning and electrochemical feedbacks. To solve this problem,we develop a novel fabrication method of the gold nanoelectrodes: firstly, a micropipette with nanomter-sized orifice was prepared as the template by a laser puller; secondly, the inside wall of micropipette apex was blocked by compact and conic Au nano-piece through electroless plating; thirdly, the Au nano-piece was grown by bipolar electroplating and connected with a silver wire as a current collector. The fabricated Au nanoelectrode has very good voltammetric responses for the electrodic processes of both mass transfer and adsorption. The advantage lies in that it is well encapsulated by a thin glass sealing layer with a RG value lowered to 1.3, which makes it qualified in the SECM-STM coupling mode. On one hand, it can serve as STM tip for positioning which ensures the high spatial resolution; on the other hand, it is a high-quality nanoelectrode to explore the local chemical activity of the substrate. The nanofabrication method may promote the SPM techniques to obtain simultaneously the physical and chemical images with nanoscale spatial resolution, which opens a new approach to tip chemistry in electrochemical nanocatalysis and tip-enhanced spectroscopy. | Fang-Fang Wang Wei Wang Xi He Lianhuan Han Jian-Zhang Zhou Zhong-Qun Tian Zhao-Wu Tian Dongping Zhan | 2017 | Science China Chemistry2017，60，5： | 2 |
| 3 | Electrochemical hydrogen-storage capacity of graphene can achieve a carbon-hydrogen atomic ratio of 1:1显示文摘As a promising hydrogen-storage material,graphene is expected to have a theoretical capacity of 7.7 wt%,which means a carbon-hydrogen atomic ratio of 1:1.However,it has not been demonstrated yet by experiment,and the aim of the U.S.Department of Energy is to achieve 5.5 wt%in 2025.We designed a spatially-confined electrochemical system and found that the storage capacity of hydrogen adatoms on single layer graphene(SLG)is as high as 7.3 wt%,which indicates a carbon-hydrogen atomic ratio of 1:1 by considering the sp^(3) defects of SLG.First,SLG was deposited on a large-area polycrystalline platinum(Pt)foil by chemical vapor deposition(CVD);then,a micropipette with reference electrode,counter electrode and electrolyte solution inside was impacted on the SLG/Pt foil(the working electrode)to construct the spatially-confined electrochemical system.The SLG-uncovered Pt atoms act as the catalytic sites to convert protons(H^(+))to hydrogen adatoms(H_(ad)),which then spill over and are chemically adsorbed on SLG through surface diffusion during the cathodic scan.Because the electrode processes are reversible,the H_(ad) amount can be measured by the anodic stripping charge.This is the first experimental evidence for the theoretically expected hydrogen-storage capacity on graphene at ambient environment,especially by using H+rather than hydrogen gas(H_(2))as the hydrogen source,which is of significance for the practical utilization of hydrogen energy. | Quanfeng He Lanping Zeng Lianhuan Han Juan Peng Matthew M.Sartin Yuan-Zhi Tan Dongping Zhan Zhong-Qun Tian | 2022 | Science China Chemistry2022，65，2： | 2 |
| 4 | Generation/collection mode of SECM with combined probe显示文摘这里,我们报导扫描电气化学的显微镜学, theta micropipette 在被采用支持薄中央玻璃墙分开的二个邻近的 water/1,2-dichloroethane 接口的一个新奇产生 / 收集操作模式:一个人充当发电机当时其它作为收集者。当尖端来临了到 insulate 底层时,产生水流,收集水流和收集效率显著地被提高。 | Wei Wang Jie Zhang LianHuan Han DeZhi Yang Dong Ping Zhan | 2012 | Chinese Chemical Letters2012，23，1： | 1 |
| 5 | The coupling effect of slow-rate mechanical motion on the confined etching process in electrochemical mechanical micromachining显示文摘By introducing the mechanical motion into the confined etchant layer technique(CELT), we have developed a promising ultraprecision machining method, termed as electrochemical mechanical micromachining(ECMM), for producing both regular and irregular three dimensional(3 D) microstructures. It was found that there was a dramatic coupling effect between the confined etching process and the slow-rate mechanical motion because of the concentration distribution of electrogenerated etchant caused by the latter. In this article, the coupling effect was investigated systemically by comparing the etchant diffusion, etching depths and profiles in the non-confined and confined machining modes. A two-dimensional(2 D) numerical simulation model was proposed to analyze the diffusion variations during the ECMM process, which is well verified by the machining experiments. The results showed that, in the confined machining mode, both the machining resolution and the perpendicularity tolerance of side faces were improved effectively. Furthermore, the theoretical modeling and numerical simulations were proved valuable to optimize the technical parameters of the ECMM process. | Lianhuan Han Yuchao Jia Yongzhi Cao Zhenjiang Hu Xuesen Zhao Shusen Guo Yongda Yan Zhongqun Tian Dongping Zhan | 2018 | Science China Chemistry2018，61，6： | 1 |
| 6 | Spatially-separated and photo-enhanced semiconductor corrosion processes for high-efficient and contamination-free electrochemical nanoimprint lithography显示文摘Free of any thermoplastic or photocuring resists, electrochemical nanoimprint lithography(ECNL) has emerged as an alternative nanoimprint way to fabricate three-dimensional micro/nano-structures(3D-MNSs) directly on a semiconductor wafer by a spatially-confined corrosion reaction induced by the metal/semiconductor contact potential. However, the consumption of electron acceptors in the ultrathin electrolyte between imprint mold and semiconductor wafer will slow down or even cease the corrosion rate. To solve this problem, we change the short-circuited corrosion cell into a spatially-separated primary cell: the imprint mold compacted gallium arsenide(GaAs) wafer in the anodic chamber while the platinum(Pt) plate connected to the imprint mold in the cathodic chamber. Thus, the GaAs corrosion rate will be stabilized in its limiting steady-state current density because of the abundant source of electron acceptors in the catholic chamber. The corrosion processes can be photo-enhanced by white-light illumination. Consequently, both the accuracy and the efficiency are promoted dramatically, which are demonstrated by the excellent performance of the fabricated binary optical elements. Moreover, the contamination problem caused by the electron acceptors is totally avoided. All the results prove that this novel ECNL mode is competitive and prospective in imprinting 3D-MNSs directly on semiconductor wafer. | Hantao Xu Lianhuan Han Jian-Jia Su Zhong-Qun Tian Dongping Zhan | 2022 | Science China Chemistry2022，65，4： | 0 |
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