Note: A quartz cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope measurements Zhigang Xia, Jihao Wang, Yubin Hou, and Qingyou Lu Citation: Review of Scientific Instruments 85, 096103 (2014); doi: 10.1063/1.4894470 View online: http://dx.doi.org/10.1063/1.4894470 View Table of Contents: http://scitation.aip.org/content/aip/journal/rsi/85/9?ver=pdfcov Published by the AIP Publishing Articles you may be interested in A high stability and repeatability electrochemical scanning tunneling microscope Rev. Sci. Instrum. 85, 125103 (2014); 10.1063/1.4902975 Note: Automated electrochemical etching and polishing of silver scanning tunneling microscope tips Rev. Sci. Instrum. 84, 096109 (2013); 10.1063/1.4822115 Scanning tunneling microscope observation and magnetic anisotropy of molecular beam epitaxy-grown Fe/Pt superlattices with (111) and (001) orientations J. Appl. Phys. 95, 7285 (2004); 10.1063/1.1667421 Scanning tunneling microscope measurements of the amplitude of vibration of a quartz crystal oscillator J. Appl. Phys. 88, 4017 (2000); 10.1063/1.1289235 The use of a special work station for in situ measurements of highly reactive electrochemical systems by atomic force and scanning tunneling microscopes Rev. Sci. Instrum. 70, 4668 (1999); 10.1063/1.1150130
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP: 129.174.21.5 On: Mon, 22 Dec 2014 05:41:36
REVIEW OF SCIENTIFIC INSTRUMENTS 85, 096103 (2014)
Note: A quartz cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope measurements Zhigang Xia,1,2 Jihao Wang,1,2 Yubin Hou,1 and Qingyou Lu1,2,a) 1 High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China 2 Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
(Received 14 March 2014; accepted 21 August 2014; published online 3 September 2014) In this paper, we provide and demonstrate a design of a unique cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope (ECSTM) measurements. The active metal Pt electrode can be protected from air contamination during the preparation process. The transparency of the cell allows the tip and bead to be aligned by direct observation. Based on this, a new and effective alignment method is introduced. The high-quality bead preparations through this new cell have been confirmed by the ECSTM images of Pt (111). © 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4894470] The single crystal bead, prepared by Clavilier’s method,1 has eight natural (111) facets in an octahedral configuration. It now becomes commonly used for the electrochemical scanning tunneling microscope (ECSTM) measurement because its preparation is easy and the so obtained (111) facets are free of scratches in large scale.2, 3 However, the common way for bead (especially for Pt bead) preparation has its own limitations, in which the (111) facets are readily contaminated by air. In general, before the ECSTM measurement, the initially formed bead is heated in flame and then cooled in an inert or reducing atmosphere.4–9 It is then mounted in the cell. The last step has to be exposed in air for a few minutes, in which the (111) facet of the bead cannot be protected by simply putting on a drop of water because the spherical bead cannot hold water. This issue is particularly severe for active metals like Pt.2 This is why the studies of ECSTM measurements on Pt bead are hardly seen even up to now. In this paper, we present the design and performance tests of a cell for ECSTM applications, which make us successfully obtain high quality ECSTM images on Pt bead. This new cell allows the bead to be protected from air contamination during the entire process of (111) facet preparation and alignment. A new method of readily and precisely aligning the tip to the (111) facet of the bead is also introduced. The performance of the cell is tested in a home-built ECSTM, which results in the realization of large area and high quality (111) surface on the Pt bead as shown by the ECSTM image. An atomically resolved ECSTM image of the (111) facet of an Au bead is also presented to show the high stability of the cell. Figure 1(a) shows the structure of the new cell, which mainly consists of a quartz reservoir and a quartz bead holder of U-shape. Quartz has low thermal expansion coefficient (0.55 ppm/◦ C), which can reduce drifting in scanning an atomic resolution image. The 25 mm long reservoir is cut from a quartz tube of 15 mm outer diameter and 12 mm inner a) Author to whom correspondence should be addressed. Electronic mail:
[email protected]. Tel.: 86-551-6360-0247.
0034-6748/2014/85(9)/096103/3/$30.00
diameter. The ends of the reservoir are sealed by melting with two quartz disks of 0.8 mm thick. The front window is highly flat and transparent for a clear see-through, which is important for the alignment between the STM tip and the (111) facet of the bead. The bead holder is fixed in the reservoir by melting with the bottom and the top edges of the reservoir. The bead holder allows the bead working electrode to be mounted in the cell quickly and conveniently by spring (Pt made) clamping. The bottom of reservoir is flat. Two Teflon covers are used to hold the counter and reference electrodes and to reduce the solution’s exposed area to the air. These can minimize the contamination from atmosphere. The single crystal Pt bead prepared using Clavilier’s method was about 3 mm diameter at one end of a 0.8 mm Pt wire. The unmelted Pt wire was then pressed on a vertically held platinum foil using a pair of ceramic tweezers with one of the (111) facets of the bead facing upwards (Fig. 1(a)). After heating on a Bunsen burner, the Pt wire and the Pt foil are melted together and the bead was firmly fixed on the Pt foil through the Pt wire. The (111) facet of the single crystal bead serves as the working electrode (WE) (Fig. 1(a)) which faces upward when the Pt foil is inserted in the cell vertically (Fig. 1(b)). A platinum wire and a copper wire were used as the counter electrode (CE) and reference electrode (RE), respectively. To prevent the Pt bead from exposing in air during the process of (111) facet preparation, a specially designed flask is introduced. It consists of four parts: a glass base, a glass tripod, a glass cover, and a glass cap. At first, a proper amount of oxygen-free solution was added into the cell and the cell was placed on the glass tripod which stood in the glass base. The flask was then assembled and was purged with high-purity nitrogen gas (Fig. 2(a)). The Pt bead was cleaned by annealing in butane gas flame at white heat. Upon finishing this step, we quickly removed the glass cap and held the working electrode (still in orange-yellow) in the glass flask with a pair of ceramic tweezers to cool it down in the nitrogen flow (Fig. 2(a)). The cooled bead was then clamped in the bead holder via a spring.
85, 096103-1
© 2014 AIP Publishing LLC
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP: 129.174.21.5 On: Mon, 22 Dec 2014 05:41:36
096103-2
Xia et al.
FIG. 1. (a) Exploded and (b) assembled views of the quartz cell with single crystal bead electrode.
FIG. 2. (a) Assembled view of the special flask with quartz cell. (b) The cooling and mounting process of the bead in the flask flowing with nitrogen gas.
Rev. Sci. Instrum. 85, 096103 (2014)
From then on, the bead was immersed in and protected by the solution in the reservoir. At last, the two Teflon covers were fixed on the cell (Fig. 2(b)). To avoid the distorted observation due to the refraction of the curved gas-liquid interface in the tradition cell, we observe the tip-bead alignment process horizontally in the new cell through the highly transparent quartz front window. If our new cell is used in the popular Molecular Imaging PicoSPM 5500, the well known problem of aligning the STM tip to the (111) facet of the bead in ECSTM measurements can also be easily solved. Below describes how we aligned the tip with the (111) facet of the bead. When the cell was mounted in our home-built ECSTM, we let the tip be above and in front of the bead (Fig. 3(a)). Then, we used an optical microscope to observe the tip and the top facet of the bead and make them close to each other by hand until the mirror image of the tip was seen on the bead (Fig. 3(b)). The (111) facet of the bead could be seen as a short flat line at the top of the bead. We then adjusted the cell towards left or right so that the end of the tip pointed to the center of the flat top of the bead. This would ensure that the lateral deviation was minimized. Next, the cell was moved towards the observer by a screw, which would cause the tip’s mirror image to move upwards (Fig. 3(c)). This procedure was continued until the end of the tip in the mirror image became slightly flat (Fig. 3(d)). At this moment, the tip and the (111) facet were aligned with minimized fore-and-aft deviation. After the above bead installation and tip-bead alignment were done, the ECSTM was protected in a steel chamber filled with N2 . Then the tip-sample coarse approach was performed and ECSTM images were scanned in the solutions of 0.05 M H2 SO4 + 1 mM CuSO4 , which was prepared from Milli-Q water, CuSO4 , and H2 SO4 (from Merck, Suprapur grade). ECSTM tips cut from 0.25 mm thick 80:20 Pt/Ir wires were coated with Polymethylstyrene. A constant current raw
FIG. 3. (a)–(d) Schematics showing the process of aligning the STM tip to the (111) facet of the single crystal bead.
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP: 129.174.21.5 On: Mon, 22 Dec 2014 05:41:36
096103-3
Xia et al.
FIG. 4. ECSTM images of the Pt (111) surface acquired in 0.05 M H2 SO4 + 1 mM CuSO4 . (a) Single atomic steps obtained in new cell; scan parameters: size = 250 × 250 nm2 , it = 20 nA, Vt = 600 mV, and Vs = 700 mV vs Cu/Cu2+ . (b) Single atomic steps obtained in traditional cell; scan parameters: size = 250 × 250 nm2 , it = 40 nA, Vt = 800 mV, and Vs = 700 mV vs Cu/Cu2+ .
data image of a 250 × 250 nm2 large area surface is shown in Fig. 4(a). The scan conditions were: tunneling current it = 20 nA, scan rate = 1 lines/s, tip voltage Vt = 600 mV, and sample voltage Vs = 700 mV vs. Cu/Cu2+ . Obviously, the Pt (111) surface is flat and well ordered,9, 10 showing the excellent performance of the new cell and the corresponding bead installation process. As a comparison, we also did the similar experiment in a traditional cell, in which the installation of the bead and the tip-bead alignment had to be done in air. The constant current raw data image with the same scan size is shown in Fig. 4(b) which reveals a much rougher surface.11 The scan conditions were: tunneling current it = 40 nA, scan rate = 1 lines/s, tip voltage Vt = 800 mV, and sample voltage Vs = 700 mV vs. Cu/Cu2+ . To test the stability of the new cell, we took atomic resolution images for an (111) facet of an Au bead in the solutions of 0.05 M H2 SO4 + 1 mM CuSO4 . The preparation and installation of the Au bead were very similar to those of the Pt bead except that the anneal temperature was in dark red color. Figure 5(a) presents the raw data constant height mode images of the Au (111) surface. It shows the expected hexagonally close-packed atomic lattice. The scan parameters were: scan rate = 16 lines/s, tip voltage Vt = 543 mV, and sample voltage Vs = 494 mV vs. Cu/Cu2+ . Figure 5(b) shows the sulfate structure on the Au (111) surface, which is consistent with the results in other work.12, 13 The scan parameters were: scan rate = 18 lines/s, Vt = 199 mV and Vs = 166 mV vs. Cu/Cu2+ . The high stability of the new cell is hence well confirmed. In this note, a new cell with a single crystal bead as the working electrode for the ECSTM measurement is introduced. It allows the single crystal surface to be protected against air during the whole process of sample preparation. In addition, the transparent cell allows the tip and bead to
Rev. Sci. Instrum. 85, 096103 (2014)
FIG. 5. Atomically resolved EC-STM images acquired in 0.05 M H2 SO4 + 1 mM CuSO4 . (a) Structure of the Au (111) surface, scan parameters: scan size = 5.2 × 4.0 nm2 , tip voltage Vt = 543 mV and sample voltage Vs = 494 mV vs Cu/Cu2+ . (b) Adsorption structure of sulfate on Au (111) surface, scan parameters: scan size = 5.9 × 5.3 nm2 ; Vt = 199 mV and Vs = 166 mV vs. Cu/Cu2+.
be aligned in solution in an easier and more precise manner. The advantages of the cell have been confirmed by the ECSTM images of large area Pt (111) and atomically resolved Au (111). Now, clean and well-ordered single crystal (111) surfaces on the beads of active metals like Pt are readily obtained, which were difficult to acquire previously. We expect that the applications of bead single crystals will be promoted in ECSTM. This work was supported by the project of Chinese national high magnetic field facilities, the fundamental research funds for the central universities (Program No. WK2340000035) and the National Natural Science Foundation of China under Grant Nos. U1232210, 11204306, and 11374278. 1 J.
Clavilier, R. Faure, G. Guinet, and R. Durand, J. Electroanal. Chem. Interfacial Electrochem. 107, 205 (1979). 2 D. M. Kolb, Angew. Chem., Int. Ed. 40, 1162 (2001). 3 J. W. Yan, C. F. Sun, X. S. Zhou, Y. A. Tang, and B. W. Mao, Electrochem. Commun. 9, 2716 (2007). 4 J. Clavilier, J. Electroanal. Chem. Interfacial Electrochem. 107, 211 (1979). 5 J. Clavilier, A. Rodes, K. El Achi, and M. A. Zamakhchari, J. Chim. Phys. Phys.-Chim. Biol. 88, 1291 (1991). 6 A. Hamelin, L. Doubova, D. Wagner, and H. Schirmer, J. Electroanal. Chem. Interfacial Electrochem. 220, 155 (1987). 7 Y. Uchida and G. Lehmpfuhl, Surf. Sci. 243, 193 (1991). 8 N. Batina, A. S. Dakkouri, and D. M. Kolb, J. Electroanal. Chem. 370, 87 (1994). 9 L. A. Kibler, A. Cuesta, M. Kleinert, and D. M. Kolb, J. Electroanal. Chem. 484, 73 (2000). 10 N. M. Markovic, M. Hanson, G. McDougall, and E. Yeager, J. Electroanal. Chem. Interfacial Electrochem. 214, 555 (1986). 11 S. Motoo and N. Furuya, J. Electroanal. Chem. Interfacial Electrochem. 172, 339 (1984). 12 G. J. Edens, X. P. Gao, and M. J. Weaver, J. Electroanal. Chem. 375, 357 (1994). 13 Z. Shi and J. Lipkowski, J. Electroanal. Chem. 365, 303 (1994).
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP: 129.174.21.5 On: Mon, 22 Dec 2014 05:41:36
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP: 129.174.21.5 On: Mon, 22 Dec 2014 05:41:36
REVIEW OF SCIENTIFIC INSTRUMENTS 85, 096103 (2014)
Note: A quartz cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope measurements Zhigang Xia,1,2 Jihao Wang,1,2 Yubin Hou,1 and Qingyou Lu1,2,a) 1 High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China 2 Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
(Received 14 March 2014; accepted 21 August 2014; published online 3 September 2014) In this paper, we provide and demonstrate a design of a unique cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope (ECSTM) measurements. The active metal Pt electrode can be protected from air contamination during the preparation process. The transparency of the cell allows the tip and bead to be aligned by direct observation. Based on this, a new and effective alignment method is introduced. The high-quality bead preparations through this new cell have been confirmed by the ECSTM images of Pt (111). © 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4894470] The single crystal bead, prepared by Clavilier’s method,1 has eight natural (111) facets in an octahedral configuration. It now becomes commonly used for the electrochemical scanning tunneling microscope (ECSTM) measurement because its preparation is easy and the so obtained (111) facets are free of scratches in large scale.2, 3 However, the common way for bead (especially for Pt bead) preparation has its own limitations, in which the (111) facets are readily contaminated by air. In general, before the ECSTM measurement, the initially formed bead is heated in flame and then cooled in an inert or reducing atmosphere.4–9 It is then mounted in the cell. The last step has to be exposed in air for a few minutes, in which the (111) facet of the bead cannot be protected by simply putting on a drop of water because the spherical bead cannot hold water. This issue is particularly severe for active metals like Pt.2 This is why the studies of ECSTM measurements on Pt bead are hardly seen even up to now. In this paper, we present the design and performance tests of a cell for ECSTM applications, which make us successfully obtain high quality ECSTM images on Pt bead. This new cell allows the bead to be protected from air contamination during the entire process of (111) facet preparation and alignment. A new method of readily and precisely aligning the tip to the (111) facet of the bead is also introduced. The performance of the cell is tested in a home-built ECSTM, which results in the realization of large area and high quality (111) surface on the Pt bead as shown by the ECSTM image. An atomically resolved ECSTM image of the (111) facet of an Au bead is also presented to show the high stability of the cell. Figure 1(a) shows the structure of the new cell, which mainly consists of a quartz reservoir and a quartz bead holder of U-shape. Quartz has low thermal expansion coefficient (0.55 ppm/◦ C), which can reduce drifting in scanning an atomic resolution image. The 25 mm long reservoir is cut from a quartz tube of 15 mm outer diameter and 12 mm inner a) Author to whom correspondence should be addressed. Electronic mail:
[email protected]. Tel.: 86-551-6360-0247.
0034-6748/2014/85(9)/096103/3/$30.00
diameter. The ends of the reservoir are sealed by melting with two quartz disks of 0.8 mm thick. The front window is highly flat and transparent for a clear see-through, which is important for the alignment between the STM tip and the (111) facet of the bead. The bead holder is fixed in the reservoir by melting with the bottom and the top edges of the reservoir. The bead holder allows the bead working electrode to be mounted in the cell quickly and conveniently by spring (Pt made) clamping. The bottom of reservoir is flat. Two Teflon covers are used to hold the counter and reference electrodes and to reduce the solution’s exposed area to the air. These can minimize the contamination from atmosphere. The single crystal Pt bead prepared using Clavilier’s method was about 3 mm diameter at one end of a 0.8 mm Pt wire. The unmelted Pt wire was then pressed on a vertically held platinum foil using a pair of ceramic tweezers with one of the (111) facets of the bead facing upwards (Fig. 1(a)). After heating on a Bunsen burner, the Pt wire and the Pt foil are melted together and the bead was firmly fixed on the Pt foil through the Pt wire. The (111) facet of the single crystal bead serves as the working electrode (WE) (Fig. 1(a)) which faces upward when the Pt foil is inserted in the cell vertically (Fig. 1(b)). A platinum wire and a copper wire were used as the counter electrode (CE) and reference electrode (RE), respectively. To prevent the Pt bead from exposing in air during the process of (111) facet preparation, a specially designed flask is introduced. It consists of four parts: a glass base, a glass tripod, a glass cover, and a glass cap. At first, a proper amount of oxygen-free solution was added into the cell and the cell was placed on the glass tripod which stood in the glass base. The flask was then assembled and was purged with high-purity nitrogen gas (Fig. 2(a)). The Pt bead was cleaned by annealing in butane gas flame at white heat. Upon finishing this step, we quickly removed the glass cap and held the working electrode (still in orange-yellow) in the glass flask with a pair of ceramic tweezers to cool it down in the nitrogen flow (Fig. 2(a)). The cooled bead was then clamped in the bead holder via a spring.
85, 096103-1
© 2014 AIP Publishing LLC
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP: 129.174.21.5 On: Mon, 22 Dec 2014 05:41:36
096103-2
Xia et al.
FIG. 1. (a) Exploded and (b) assembled views of the quartz cell with single crystal bead electrode.
FIG. 2. (a) Assembled view of the special flask with quartz cell. (b) The cooling and mounting process of the bead in the flask flowing with nitrogen gas.
Rev. Sci. Instrum. 85, 096103 (2014)
From then on, the bead was immersed in and protected by the solution in the reservoir. At last, the two Teflon covers were fixed on the cell (Fig. 2(b)). To avoid the distorted observation due to the refraction of the curved gas-liquid interface in the tradition cell, we observe the tip-bead alignment process horizontally in the new cell through the highly transparent quartz front window. If our new cell is used in the popular Molecular Imaging PicoSPM 5500, the well known problem of aligning the STM tip to the (111) facet of the bead in ECSTM measurements can also be easily solved. Below describes how we aligned the tip with the (111) facet of the bead. When the cell was mounted in our home-built ECSTM, we let the tip be above and in front of the bead (Fig. 3(a)). Then, we used an optical microscope to observe the tip and the top facet of the bead and make them close to each other by hand until the mirror image of the tip was seen on the bead (Fig. 3(b)). The (111) facet of the bead could be seen as a short flat line at the top of the bead. We then adjusted the cell towards left or right so that the end of the tip pointed to the center of the flat top of the bead. This would ensure that the lateral deviation was minimized. Next, the cell was moved towards the observer by a screw, which would cause the tip’s mirror image to move upwards (Fig. 3(c)). This procedure was continued until the end of the tip in the mirror image became slightly flat (Fig. 3(d)). At this moment, the tip and the (111) facet were aligned with minimized fore-and-aft deviation. After the above bead installation and tip-bead alignment were done, the ECSTM was protected in a steel chamber filled with N2 . Then the tip-sample coarse approach was performed and ECSTM images were scanned in the solutions of 0.05 M H2 SO4 + 1 mM CuSO4 , which was prepared from Milli-Q water, CuSO4 , and H2 SO4 (from Merck, Suprapur grade). ECSTM tips cut from 0.25 mm thick 80:20 Pt/Ir wires were coated with Polymethylstyrene. A constant current raw
FIG. 3. (a)–(d) Schematics showing the process of aligning the STM tip to the (111) facet of the single crystal bead.
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP: 129.174.21.5 On: Mon, 22 Dec 2014 05:41:36
096103-3
Xia et al.
FIG. 4. ECSTM images of the Pt (111) surface acquired in 0.05 M H2 SO4 + 1 mM CuSO4 . (a) Single atomic steps obtained in new cell; scan parameters: size = 250 × 250 nm2 , it = 20 nA, Vt = 600 mV, and Vs = 700 mV vs Cu/Cu2+ . (b) Single atomic steps obtained in traditional cell; scan parameters: size = 250 × 250 nm2 , it = 40 nA, Vt = 800 mV, and Vs = 700 mV vs Cu/Cu2+ .
data image of a 250 × 250 nm2 large area surface is shown in Fig. 4(a). The scan conditions were: tunneling current it = 20 nA, scan rate = 1 lines/s, tip voltage Vt = 600 mV, and sample voltage Vs = 700 mV vs. Cu/Cu2+ . Obviously, the Pt (111) surface is flat and well ordered,9, 10 showing the excellent performance of the new cell and the corresponding bead installation process. As a comparison, we also did the similar experiment in a traditional cell, in which the installation of the bead and the tip-bead alignment had to be done in air. The constant current raw data image with the same scan size is shown in Fig. 4(b) which reveals a much rougher surface.11 The scan conditions were: tunneling current it = 40 nA, scan rate = 1 lines/s, tip voltage Vt = 800 mV, and sample voltage Vs = 700 mV vs. Cu/Cu2+ . To test the stability of the new cell, we took atomic resolution images for an (111) facet of an Au bead in the solutions of 0.05 M H2 SO4 + 1 mM CuSO4 . The preparation and installation of the Au bead were very similar to those of the Pt bead except that the anneal temperature was in dark red color. Figure 5(a) presents the raw data constant height mode images of the Au (111) surface. It shows the expected hexagonally close-packed atomic lattice. The scan parameters were: scan rate = 16 lines/s, tip voltage Vt = 543 mV, and sample voltage Vs = 494 mV vs. Cu/Cu2+ . Figure 5(b) shows the sulfate structure on the Au (111) surface, which is consistent with the results in other work.12, 13 The scan parameters were: scan rate = 18 lines/s, Vt = 199 mV and Vs = 166 mV vs. Cu/Cu2+ . The high stability of the new cell is hence well confirmed. In this note, a new cell with a single crystal bead as the working electrode for the ECSTM measurement is introduced. It allows the single crystal surface to be protected against air during the whole process of sample preparation. In addition, the transparent cell allows the tip and bead to
Rev. Sci. Instrum. 85, 096103 (2014)
FIG. 5. Atomically resolved EC-STM images acquired in 0.05 M H2 SO4 + 1 mM CuSO4 . (a) Structure of the Au (111) surface, scan parameters: scan size = 5.2 × 4.0 nm2 , tip voltage Vt = 543 mV and sample voltage Vs = 494 mV vs Cu/Cu2+ . (b) Adsorption structure of sulfate on Au (111) surface, scan parameters: scan size = 5.9 × 5.3 nm2 ; Vt = 199 mV and Vs = 166 mV vs. Cu/Cu2+.
be aligned in solution in an easier and more precise manner. The advantages of the cell have been confirmed by the ECSTM images of large area Pt (111) and atomically resolved Au (111). Now, clean and well-ordered single crystal (111) surfaces on the beads of active metals like Pt are readily obtained, which were difficult to acquire previously. We expect that the applications of bead single crystals will be promoted in ECSTM. This work was supported by the project of Chinese national high magnetic field facilities, the fundamental research funds for the central universities (Program No. WK2340000035) and the National Natural Science Foundation of China under Grant Nos. U1232210, 11204306, and 11374278. 1 J.
Clavilier, R. Faure, G. Guinet, and R. Durand, J. Electroanal. Chem. Interfacial Electrochem. 107, 205 (1979). 2 D. M. Kolb, Angew. Chem., Int. Ed. 40, 1162 (2001). 3 J. W. Yan, C. F. Sun, X. S. Zhou, Y. A. Tang, and B. W. Mao, Electrochem. Commun. 9, 2716 (2007). 4 J. Clavilier, J. Electroanal. Chem. Interfacial Electrochem. 107, 211 (1979). 5 J. Clavilier, A. Rodes, K. El Achi, and M. A. Zamakhchari, J. Chim. Phys. Phys.-Chim. Biol. 88, 1291 (1991). 6 A. Hamelin, L. Doubova, D. Wagner, and H. Schirmer, J. Electroanal. Chem. Interfacial Electrochem. 220, 155 (1987). 7 Y. Uchida and G. Lehmpfuhl, Surf. Sci. 243, 193 (1991). 8 N. Batina, A. S. Dakkouri, and D. M. Kolb, J. Electroanal. Chem. 370, 87 (1994). 9 L. A. Kibler, A. Cuesta, M. Kleinert, and D. M. Kolb, J. Electroanal. Chem. 484, 73 (2000). 10 N. M. Markovic, M. Hanson, G. McDougall, and E. Yeager, J. Electroanal. Chem. Interfacial Electrochem. 214, 555 (1986). 11 S. Motoo and N. Furuya, J. Electroanal. Chem. Interfacial Electrochem. 172, 339 (1984). 12 G. J. Edens, X. P. Gao, and M. J. Weaver, J. Electroanal. Chem. 375, 357 (1994). 13 Z. Shi and J. Lipkowski, J. Electroanal. Chem. 365, 303 (1994).
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitationnew.aip.org/termsconditions. Downloaded to IP: 129.174.21.5 On: Mon, 22 Dec 2014 05:41:36
