The electrochemical detection of heavy metal ions is reported using an inexpensive portable in-house built potentiostat and epitaxial graphene. Monolayer, hydrogen-intercalated quasi-freestanding bilayer, and multilayer epitaxial graphene were each tested as working electrodes before and after modification with an oxygen plasma etch to introduce oxygen chemical groups to the surface. The graphene samples were characterized using X-ray photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy, and van der Pauw Hall measurements. Dose-response curves in seawater were evaluated with added trace levels of four heavy metal salts (CdCl, CuSO, HgCl, and PbCl), along with detection algorithms based on machine learning and library development for each form of graphene and its oxygen plasma modification. Oxygen plasma-modified, hydrogen-intercalated quasi-freestanding bilayer epitaxial graphene was found to perform best for correctly identifying heavy metals in seawater.
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http://dx.doi.org/10.3390/s22145367 | DOI Listing |
Micron
December 2024
School of Chemical and Biological Engineering, and Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea; Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul National University, Seoul 08826, Republic of Korea; Advanced Institute of Convergence Technology, Seoul National University, Suwon 16229, Republic of Korea; Institute of Engineering Research, College of Engineering, Seoul National University, Seoul 08826, Republic of Korea. Electronic address:
Graphene's exceptional physical properties, such as high thermal conductivity and mechanical strength, have attracted significant interest for its integration in transistors and thermal interface materials. While achieving various conformations of graphene is desirable for such applications, synthesizing graphene with target conformations remains a challenge. In this work, we present a method for synthesizing multilayer graphene with ridged conformations, using a microscale ridge-patterned copper (Cu) layer that was epitaxially deposited on a sapphire substrate.
View Article and Find Full Text PDFACS Nano
December 2024
College of Energy, Soochow Institute for Energy and Materials InnovationS (SIEMIS), Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou 215123, P. R. China.
An accurate assessment of the electrodeposition mechanism is essential for evaluating the electrochemical stability and reversibility of the metal anodes. Multiple strategies aimed at uniform Zn deposition have been extensively reported, yet it is challenging to clarify the Zn crystal growth regularity and activity due to the obscured physicochemical properties of as-deposited Zn. Herein, we present a protocol for elucidating the controlled epitaxial growth process of Zn crystals and quantifying their surface electrochemical activity using scanning electrochemical microscopy.
View Article and Find Full Text PDFNano Lett
December 2024
Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing 211189, China.
Spin pumping has been reported on interfaces formed with ferromagnetic metals and layered transition-metal dichalcogenides (TMDs), as signified by enhanced Gilbert damping parameters extracted from magnetodynamics measurements. However, whether the observed damping enhancement purely arises from the pumping effect has remained debatable, given that possible extrinsic disturbances on the interfaces cannot be excluded in most of the experiments. Here, we explore an atomically clean interface formed with CoFeB and atomically thin MoSe, achieved by an all growth strategy based on molecular beam epitaxy.
View Article and Find Full Text PDFNanomaterials (Basel)
December 2024
School of Integrated Circuits and Electronics & Yangtze Delta Region Academy, Beijing Institute of Technology (BIT), Beijing 100081, China.
In this study, we explore the substrate-mediated control of self-assembly behavior in diboron molecules (CHBO, BCat) using scanning tunneling microscopy (STM). The structural transformation of BCat molecules from one-dimensional (1D) molecular chains to two-dimensional (2D) molecular arrays was achieved by changing the substrate from Au(111) to bilayer graphene (BLG), highlighting the key role of substrate interactions in determining the assembly structure. Notably, the B-B bond in the molecular arrays on BLG is distinctly pronounced, reflecting a more refined molecular resolution with distinct electronic states than that on Au(111).
View Article and Find Full Text PDFSmall
December 2024
School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
Introducing uniform magnetic order in two-dimensional (2D) topological insulators by constructing heterostructures of TI and magnet is a promising way to realize the high-temperature Quantum Anomalous Hall effect. However, the topological properties of 2D materials are susceptible to several factors that make them difficult to maintain, and whether topological interface states (TISs) can exist at magnetic-topological heterostructure interfaces is largely unknown. Here, it is experimentally shown that TISs in a lateral heterostructure of CrTe/Bi(110) are robust against disorder, defects, high magnetic fields (time-reversal symmetry-breaking perturbations), and elevated temperature (77 K).
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