Theoretical prediction of interfacial capacitance in graphene-based supercapacitors is crucial to accelerating materials' design and development cycles. However, there is currently a significant gap between ab initio predictions and experimental reports, particularly in the case of nitrogen-doped graphene. Analyses based on changes to the density of states of freestanding graphene upon doping do not account for the electronic interactions between the electrode, dopants, and substrates.
View Article and Find Full Text PDFLinear sweep and cyclic voltammetry techniques are important tools for electrochemists and have a variety of applications in engineering. Voltammetry has classically been treated with the Randles-Sevcik equation, which assumes an electroneutral supported electrolyte. In this paper, we provide a comprehensive mathematical theory of voltammetry in electrochemical cells with unsupported electrolytes and for other situations where diffuse charge effects play a role, and present analytical and simulated solutions of the time-dependent Poisson-Nernst-Planck equations with generalized Frumkin-Butler-Volmer boundary conditions for a 1:1 electrolyte and a simple reaction.
View Article and Find Full Text PDFThe interactions of H2O and H2S monomers with Cu(111) in the absence and presence of an external electric field are studied using density functional theory. It is found that the adsorption is accompanied by a rippled pattern of the surface Cu atoms and electron accumulation on the surface Cu atoms surrounding the adsorption site. The response of the H2O/Cu(111) and H2S/Cu(111) interfaces to the external electric field is computed up to the field magnitude of 10(10) V m(-1).
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
January 2012
Piezoelectric devices, such as piezoelectric traveling- wave rotary ultrasonic motors, have composite piezoelectric structures. A composite piezoelectric structure consists of a combination of two or more bonded materials, at least one of which is a piezoelectric transducer. Piezoelectric structures have mainly been numerically modeled using the finite element method.
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
July 2010
A partial differential equation (PDE) model for the dynamics of a thin piezoelectric plate in an electric field is presented. This PDE model is discretized via the finite volume method (FVM), resulting in a system of coupled ordinary differential equations. A static analysis and an eigenfrequency analysis are done with results compared with those provided by a commercial finite element (FEM) package.
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