Copper oxide – PANI derived novel composites for the kinetic tuning of MgH2

As a promising hydrogen storage material with high gravimetric density and low cost, MgH2 is an attractive candidate for practical application but still facing limitations due to its poor kinetics. In this work, the nanostructured CuxO mateirals in PANI matrix were developed as catalysts to enhance the hydrogen desorption behaviors of MgH2 in the form of PANI, CuxO/PANI-1, CuxO/PANI-2, and CuxO/PANI-3. The CuxO/PANI catalyst is effective in decreasing the desorption peak temperature of MgH2 and among all the forms of this catalyst, the catalytic efficiency of CuxO/PANI-3 was found significantly higher as compared to the others. Thermal analysis measurements show that the desorption peak temperature of CuxO/PANI-3 doped MgH2 is reduced to 304 °C in comparison to 347 °C of the undoped MgH2. At the same time, the activation energy of hydrogen desorption is also reduced to 135.6 kJ/mol, whereas it was observed as 171 kJ/mol for pristine MgH2. Structural identification from X-ray diffraction profile reveals that CuO phase is significantly present that might have contributed to the kinetic tuning of MgH2 by the addition of CuxO/PANI-3 as catalyst. Furthermore, the effect of extending milling period on the catalytic behavior has been investigated in case of MgH2+10 wt% CuxO/PANI-3 composite. The lesser reduction in the dehydrogenation peak temperature and no change in the onset desorption temperature indicate that kinetic tuning of MgH2 cannot be improved by prolonged milling.