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We report a novel approach to probe the local ion concentration at graphene/water interfaces using in situ Raman spectroscopy. Here, the upshifts observed in the G band Raman mode under applied electrochemical potentials are used to determine the charge density in the graphene sheet. For voltages up to ±0.8 V vs. NHE, we observe substantial upshifts in the G band Raman mode by as much as 19 cm-1, which corresponds to electron and hole carrier densities of 1.4 × 1013 cm-2 and Fermi energy shifts of ±430 meV. The charge density in the graphene electrode is also measured independently using the capacitance-voltage characteristics (i.e., Q = CV), and is found to be consistent with those measured by Raman spectroscopy. From charge neutrality requirements, the ion concentration in solution per unit area must be equal and opposite to the charge density in the graphene electrode. Based on these charge densities, we estimate the local ion concentration as a function of electrochemical potential in both pure DI water and 1 M KCl solutions, which span a pH range from 3.8 to 10.4 for pure DI water and net ion concentrations of ±0.7 mol L-1 for KCl under these applied voltages.
This article was published in the following journal.
A newly self-supported electrode composed of MnO on Ni foam/graphene (NF/graphene/MnO) was synthesized in situ by electrodeposition, and was used as a supercapacitor electrode for the first time. An u...
In this work, we report a methodology for the quantification of Homocysteine (HcySH) at neutral pH (pH-7.0) using Au nanoparticles incorporated reduced graphene oxide (AuNP/rGO/GCE) modified glassy ca...
Although there is significant progress in the chemical vapor deposition (CVD) of graphene on Cu surfaces, the industrial application of graphene is not realized yet. One of the most critical obstacles...
Unique nanostructure, high electrical conductivity, satisfactory energy density, and extraordinary cycling stability are important evaluation criteria for high-efficient energy storage devices. Herein...
A selective biosensing platform for the determination of hypoxanthine (Hx) and uric acid (UA) concentrations in both buffer and human serum sample solutions was developed. The biosensor features the l...
The objective of this study is two fold, first to explore the potential of context sensitive intervention delivery to provide in-situ support for people with depressive symptoms, second to...
In this study, investigators will show proof-of-concept that brain signals can be used in real-time, closed-loop mode to trigger stimulation for hand function. Subjects will undergo surger...
To determine safety, ablative zone, technical success rate and early safety data of recently introduced cool-wet electrode in eligible patients who are indicative for radiofrequency ablati...
Pulmonary vein (PV) isolation is very important in atrial fibrillation (AF) catheter ablation. PV reconnection is one of the main reasons in AF recurrence. Contact force-sensing catheter i...
Increasing ablative zone is an essential part to improve technical success and long term outcome in patient treated with radiofrequency ablation (RFA). A combination of dual switching sys...
A condition in which abnormal cells have not spread outside the duct, lobule, or nipple to other tissues of the breast. There are 3 types of breast carcinoma in situ: DUCTAL CARCINOMA IN SITU; LOBULAR CARCINOMA IN SITU; and PAGET DISEASE OF THE NIPPLE
An electrochemical technique for measuring the current that flows in solution as a function of an applied voltage. The observed polarographic wave, resulting from the electrochemical response, depends on the way voltage is applied (linear sweep or differential pulse) and the type of electrode used. Usually a mercury drop electrode is used.
A phenomenon where microorganisms communicate and coordinate their behavior by the accumulation of signaling molecules. A reaction occurs when a substance accumulates to a sufficient concentration. This is most commonly seen in bacteria.
A technique that labels specific sequences in whole chromosomes by in situ DNA chain elongation or PCR (polymerase chain reaction).
A class of G-protein-coupled receptors that react to varying extracellular CALCIUM levels. Calcium-sensing receptors in the PARATHYROID GLANDS play an important role in the maintenance of calcium HOMEOSTASIS by regulating the release of PARATHYROID HORMONE. They differ from INTRACELLULAR CALCIUM-SENSING PROTEINS which sense intracellular calcium levels.