Effect of microstructural parameters of ball-milled Si powder on reactivity with water to produce H2: Way forward for on-demand H2 production

Silicon (Si) nanoparticles prepared by ball-milling technique can show many exciting properties including improved reactivity with water to produce hydrogen (H2) compared to that of the bulk. This is attributed to the change in microstructural parameters such as particle size and dislocation density of nano-crystalline Si during the milling process. The understanding of such effects is of great importance for the technological applications of these Si nanoparticles in H2 generation from water for fuel cells, and our present work deals with this crucial aspect. In our present investigation, we found that ball-milling technique can be used to tailor the microstructural parameters of milled Si sample where milling time can greatly influence the particle size and dislocation density. In water-splitting experiment, we noticed that these microstructural parameters as well as state of agglomeration of milled Si samples in water have profound effect on the reactivity of Si with water to evolve H2. Furthermore, selecting the right alkali can speed up such H2 release, making rapid on-demand production of H2 viable, particularly for fuel cell applications.