Improved low-temperature hydrogen generation from NH3BH3 and TiO2 composites pretreated with water

• Mechanical mixing of NH3BH3 with TiO2 allows H2 generation at 80 °C.
• Pretreatment of TiO2 surface with water enhances H2 generation.
• Heat release in NH3BH3 interaction with adsorbed H2O species initiates H2 generation.

Ammonia borane (AB, NH3BH3) is nontoxic easily transportable solid hydride with high stability in air. In this work we demonstrate that simple mixing of AB with TiO2 (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 TiO2 and the increase of TiO2 loading considerably accelerated the rate of AB decomposition. The experimentally observed formation of B–O chemical bonds and the elevated heat emission suggest strong interaction of AB with the adsorbed water species on TiO2 surface. It has been found that this interaction proceeds at a higher rate comparing with binary AB/H2O 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.

Figure optionsDownload as PowerPoint slide