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

Hydrothermally grown ZnO nanorods show high interaction rates with H₂ when the spacing between adjacent nanorods decreases. Density functional theory calculations showed the interaction between nanorod surfaces in-registry is attractive at separations < 5 Å, 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 Å was found to be sufficient for H₂ 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.