Facile synthesis of Cu nanoparticles on different morphology ZrO2 supports for catalytic hydrogen generation from ammonia borane

Abstract

In this paper, the X% Cu–ZrO2 (X = 0, 1, 5, 10, 15 and 20) xerogel catalysts have been successfully synthesized via a facile two-step approach involving epoxide-driven sol–gel method followed by chemical reduction. The series xerogel catalysts were characterized using XRD, SEM–EDS, TEM, XPS, H2-TPR, N2 adsorption–desorption and FT-IR. The results showed that the morphologies of ZrO2 partly have changed from bulk to nanorods with the increase in Cu loading from 0 to 20%. The catalysts exerted Cu content-dependent activities towards the catalytic hydrolysis of ammonia borane (AB). Among them, the 15% Cu–ZrO2 showed the best catalytic activity that the maximum hydrogen generation rate was 0.384 mol min−1. The hydrolysis reaction towards AB was proved to the first order by the 15% Cu–ZrO2 xerogel by kinetic studies. The activation energy was calculated to be 22.34 kJ mol−1. Even after five recycle experiment, the catalysts also showed a good recycle stability in aqueous solution.