Improved low-temperature hydrogen generation from NH_3BH_3 and TiO_2 composites pretreated with water

摘要

Ammonia borane (AB, NH_3BH_3) is nontoxic easily transportable solid hydride with high stability in air. In this work we demonstrate that simple mixing of AB with TiO_2 (anatase) allows for hydrogen gas to be generated at temperatures as low as 80 °C. No losses of hydrogen have been observed during preparation of hydride-containing composites. It was shown that the adsorption of water vapor on TiO_2 and the increase of TiO_2 loading considerably accelerated the rate of AB decomposition. The experimentally observed for-mation of B-O chemical bonds and the elevated heat emission suggest strong interaction of AB with the adsorbed water species on TiO_2 surface. It has been found that this inter-action proceeds at a higher rate comparing with binary AB/H_2O systems. The heat being released in the process is thought to contribute to overcoming the activation barrier in the dehydrogenation of ammonia borane to produce hydrogen gas.