Microstructures and Properties of WC/Natural Zeolite Composites

Abstract

WC/zeolite nanocomposites were prepared by ball-milling a mixture of ammonia metatungsten(AMT) and zeolite and then reducing the ball-milled precursor under mixed CH4/H2 atmosphere at 900℃.The effects of carbonization time on the microstructure,phase composition,and WC distribution of as-prepared nanocomposites were investigated by X-ray diffraction(XRD),high resolution transmission electron microscope(HRTEM),and scanning transmission electron microscope(STEM).The electrocatalytic activities in alkaline solutions of these nanocomposites were evaluated in a three-electrode system by a powder microelectrode method.Due to the porous structure and high surface area of zeolite,the ball-milled AMT/zeolite precursor could be rapidly reduced in a mixed CH4/H2 atmosphere and then formed WC/zeolite nanocomposites.It was found that the active formed phase mainly composed of W2C and WC which were highly dispersed and extremely small-sized.The results also showed that the WC/zeolite nanocomposite obtained by carbonizing the ball-milled precursor for 4 h exhibited the best electrocatalytic activity,because this sample had smallest-sized and highest relative concents of tungsten carbide.