3.2. Hydrogen storage of CdO nanoperticles
As shown in Figure 6, the measurement proved that cadmium oxide has the
ability to store hydrogen at a pressure of 20 bar, with a value of 0.132
Wt.%H2. After that, the storage continued to increase
by increasing the pressure until it reached the highest storage value,
which amounted to 2.85 Wt.%H2 at a pressure of 80 bar,
after which the increase in pressure did not have any effect on the
ability to store [21].
The Van’t Hoff equation proves that the storage process has a regression
coefficient value of 0.97. Through the slope and intercept, the enthalpy
value reached 0.62607 KJ/mol H2, while the entropy value
reached 3.35697 J/mol H2, which means that the
adsorption is of the physical type [21-24]. In any case, the
temperature change did not have an effect on the weight value, because
the pressure change was relatively small, which means that it is
possible to reach the highest storage without the need for a low
temperature. See Figure 7 and Table 1.
Figure 6: Hydrogen storage isotherm in CdO nanoparticles at 223 K
Figure 7: Vant Hoff plot (1/T Vs. Ln P) of equilibrium pressures and the
linear fit to the data
Table 1: Thermodynamic properties of H2 storage in CdO
NPs