Oxygen Evolution Reaction/Oygen Reduction Reaction Properties of Massively Synthesized a NiMoS with Solvothermal Method

The oxygen electrode is the most important component in lithium-air batteries for oxygen reduction and evolution reaction (OER/ORR) to get closer to the theoretical energy density of 11,238 Wh/kg, which is the best among the batteries ever developed. Many carbon materials have been researched as a candidate oxygen electrode for lithium-air batteries such as a carbon black, CNTs and graphene. Compared to the many research results, there are still many controversies on the optimum oxygen electrode for lithium-air batteries. Besides that, carbon and binder have been known to deteriorate OER/ORR properties for lithium-air batteries by generating Li2CO3 and other bi-product. Recently, HER and OER properties of heterogeneous MoS2/Ni3S2 have been reported for water splitting. The heterogeneous HER and OER performances of MoS2/Ni3S2 were better than the commercial HER and OER catalysts. Up till now, to my best knowledge, there's no report on ORR properties for homogeneous NiMoS. Therefore, to investigate the ORR properties of homogeneous NiMoS, the homogeneous NiMoS has been synthesized on Ni-foam as well as Ni-powder by various solvothermal methods such as applying to stir during solvothermal synthesis, increasing the pressure or applying the both. Finally, we successfully synthesized NiMoS massively with stirring at the pressure of 15 bar. Characterization for NiMOSs variously synthesized were conducted with SEM, TEM as well as OER/ORR properties using RRDE (Ring Rotating Disk Electrode). As a result, homogeneous NiMoSs massively synthesized with stirring as well as high pressure of over 15 bar shows a unique homogeneous structure with sub-micron size. However, NiMoS synthesized under 2~3bar pressure with no stirring shows the tens of micron size as well as heterogeneous structure. Intriguingly, OER/ORR properties of massively synthesized NiMoS shows much better OER/ORR properties compared to the solvothermal synthesized NiMoS with no-stirring and at the pressure of 2~3 bar. These results show a very optimistic result for non-precious electrode material for the next generation Li-air battery as well as the fuel cell field.