A catalytic effect on hydrogen absorption kinetics in Pd/Ti/Mg/Ti multilayer thin films

In this work, we have investigated the microstructural and hydrogen storage properties of a 60 layer film of Pd(40 nm)/Ti(x nm)/Mg(360 nm)/Ti(x nm) (x = 10, 20, 30, 40, and 50) using an ultra-high vacuum DC magnetron sputtering system. The highest hydrogen absorption capacity of the Pd/Ti/Mg/Ti film was 4.46 wt% for x = 50. The hydrogen absorption rate accelerated remarkably with increased thickness of the Ti layer, from 209 min for x = 10 to 39 min for x = 40 - overall, an increase by a factor of similar to 5. These results demonstrate that the Ti layer in the Pd/Ti/Mg/Ti films serves as a blocking layer preventing the formation of Mg Pd intermetallic phases and provides additional diffusion paths for hydrogen atoms, which leads to enhanced hydrogen storage properties. (C) 2015 Elsevier B.V. All rights reserved.