ErMnO3/Er2Mn2O7/ZnO/GO multi-component nanocomposite as a promising material for hydrogen storage: Facile synthesis and comprehensive investigation of component roles

As part of this work, a multi-component nanocomposite with hydrogen storage capability was synthesized. To begin with, ErMnO3/ErMn2O5/ZnO were synthesized in-situ, and then graphene oxide (GO) was added. Oxygen-containing functional groups on the surface of GO acted as an oxidant, resulting in ErMn2O5 (Mn+3) being converted to Er2Mn2O7 (Mn+4). A secondary phase of ErMn2O5 was formed as a result of calcination temperatures lower than 1200 °C, facilitating the in-situ synthesis of three-component nanocomposite materials. An important aspect of this work is examining each component's role in changing the properties. Moreover, results showed that adding ZnO could change the magnetic property from ferromagnetism to paramagnetism, and thanks to GO, ferromagnetism was revealed once again. An electrochemical test confirmed that ZnO and GO could promote H2-storage capacity, increasing discharge capacity from 450 to 850 mAhg−1 and 1200 mAhg−1 during different steps. It can be considered that an increase in pore volume (about 10 times) is one of the factors contributing to this phenomenon.