Revisiting the world of metal nitrides for hydrogen storage applications
-- A DFT study
Efficient storage of hydrogen is one serious impediment in using H2as an
alternate clean fuel, at a larger scale, in the context of alarming
levels of global warming and fast depleting fossil fuel resources.Metal
nitrides such as Li2N4, Na2N4 and K2N4using density functional theory at
PBE1PBE and B3LYP functional using 6-31G (d,p), 6-31++G (d,p) and
6-311++G (d,p) as basis sets have revealed that doping of alkali-metal
atoms on the nitride systems increases their hydrogen adsorption
ability, due to electron transfer that occurs from the metal atom to the
nitrogen surface. The charged surface created around the metal atom is
found to enhance the hydrogen adsorption capacity of the complex from 9
to 16.79wt% with an average binding energy of0.06 to 0.30 eV/H2.
Various conceptual reactivity descriptors,bond parameters, Gibbs free
energy change (ΔG) and energy gap values, support the ideathat the
stability of the complex increaseson hydrogen uptake.