Preparation of Fe@C nanoparticles via hydrogen-oxygen explosion

Abstract

In order to study the growth process of Fe@C nanoparticles prepared by gas explosion method, experiments and numerical simulations of hydrogen-oxygen explosion were carried out. The influence of hydrogen concentration on the propagation of explosion wave, the variation of detonation parameters and the growth of Fe@C nanoparticles were analyzed. The results show that the hydrogen-oxygen explosion in a closed tube includes the propagation stage and the attenuation stage of the explosion wave, and they are greatly affected by the hydrogen concentration. When the hydrogen concentration increases from 66.7 vol% to 80 vol%, the detonation wave in the propagation stage will be replaced by a deflagration wave. The peak values of velocity, pressure, and temperature in the explosion process generally show a decreasing trend, and the attenuation speed in the attenuation stage gradually slows down after the explosion reaction. The morphology of Fe@C nanoparticles prepared by the hydrogen-oxygen explosion is closely related to the propagation and attenuation of explosion waves, and it can be controlled by adjusting the hydrogen concentration. When the hydrogen concentration in H₂–O₂ mixture gas is 66.7 vol%, the explosion reaction forms a severe temperature and pressure environment, and the deflagration wave in attenuation stage decays rapidly, as a result, the Fe@C nanoparticles were obtained. As the hydrogen concentration reaches 80 vol%, the velocity and attenuation speed of the deflagration wave in attenuation stage slows down, which prolongs the high-temperature time within the unit interval, and creates a relatively mild temperature and pressure environment for the growth of CNTs. Then the Fe@C nanoparticles with a large number of CNTs were prepared. This study provides a reference for the study of controlled preparation of Fe@C nanoparticles by gaseous detonation method.