“Charging”the cigarette butt:heteroatomic porous carbon nanosheets with edge-induced topological defects for enhanced oxygen evolution performance

Owing to the complexity of electron transfer pathways,the sluggish oxygen evolution reaction process is defined as the bottleneck for the practical application of Zn-air batteries.In this effort,metal nanoparticles(Co,Ni,Fe,etc.)encapsulated within nitrogen-doped carbon materials with abundant edge sites were synthesized by one-step pyrolysis treatment using cigarette butts as raw materials,which can drastically accelerate the overall rate of oxygen evolution reaction by facilitating the adsorption of oxygenated intermediates by the edge-induced topological defects.The prepared catalyst of nitrogen-doped carbon porous nanosheets loaded with Co nanoparticles(Co@NC-500)exhibits enhanced catalytic activity toward oxygen evolution reaction,with a low overpotential of 350 mV at the current density of 10 mA·cm^(-2).Furthermore,the Zn-air battery assembled with Co@NC-500 catalyst demonstrates a desirable performance affording an open-circuit potential of 1.336 V and power density of 33.6 mW·cm^(-2),indicating considerable practical application potential.

Edge-induced radiation force and torque on a cylindrically-radiating active acoustic source located near a rigid corner-space

This work examines the physical effect of the edge-induced acoustic radiation force and torque on an acoustically radiating infinitely-long circular cylindrical source,located near a rigid corner.Assuming harmonic(linear)radiating waves of the source,vibrating in monopole or dipole radiation modes near a rigid corner-space in a non-viscous fluid,the modal series expansion method in cylindrical coordinates,the classical method of images and the translational addition theorem are applied to obtain the mathematical expressions for the radiation force and torque components in exact partial-wave series.Computational results illustrate the theory,and examine some of the conditions where the radiation force and torque components vanish,which has the potential to achieve total motion suppression(i.e.,translation or rotation).Furthermore,depending on the size parameter of the source and the distances from the rigid corner space,these physical observables take positive or negative values,anticipating the prediction of pulling/pushing motions toward the corner space,and possible spinning of the source clockwise or counter-clockwise.The present analysis and its results may be useful in some applications related to underwater acoustical oceanographic engineering of submerged objects,cloaking and stealth technology development and the experimental design of elongated unmanned autonomous vehicles or submarines,as well as the manipulation of an active carrier or ultrasound contrast agents of elongated cylindrical shapes near a corner space or chamber walls at a right angle.