Interaction of hydrogen with zinc oxide nanorods: why the spacing is important

Hydrothermally grown ZnO nanorods show high interaction rates with H? when the spacing between adjacent nanorods decreases. Density functional theory calculations showed the interaction between nanorod surfaces in-registry is attractive at separations < 5 ?, while it is repulsive for out-of-registry alignments, indicating that uniform nanorods grown with their faces aligned out-of-registry are not likely to fuse due to the repulsion between the surfaces. The separation of 5 ? was found to be sufficient for H? to adsorb between the surfaces, resulting in a transfer of charge from H(2) to the surface, consistent with the measured increase in conductivity. This explains the ability of hydrogen to adsorb on closely spaced nanorods.