(A) study on nickel-based non-precious group metal catalyst for hydrogen oxidation reaction in anion exchange membrane fuel cell

Abstract

Since carbon neutral policy gradually forbids fossil fuel utilization, hydrogen become arose as green energy source. Commercialized proton exchange membrane fuel cell (PEMFC), which also adopted in motor vehicles, shows high efficiency and power density. However, catalyst used in PEMFC requires platinum as main component which significantly increase overall price of the system, and also for the Nafion membrane. In contrast to the acid condition, alkaline condition is known to be affordable in adopting non-platinum group metal (non-PGM) catalyst. This work has developed the non-PGM catalyst which consisted of Ni and MoO2 with high HOR activity and durability. Interaction between Ni and MoO2 could reduce the hydrogen binding energy (HBE) and higher metallic Ni ratio could enhance HOR activity through increasing active site. Based on this result, Ni-Mo nanoparticle (Ni-Mo NP) was synthesized and applied into full cell, which show possibility of Ni-Mo as possible candidate for anion exchange membrane fuel cell (AEMFC). For further enhancement in Ni-Mo NP, NrGO was adopted as support material, which could derive higher HOR activity with lower loading. Not only surface area increase, but also interaction between Ni-Mo and N-rGO could further decrease HBE of the catalyst and increase oxidation resistance which could enhance HOR activity. Finally, to apply NiMo catalyst into broader application of AEMFC, effect of organic component in anode fabrication was investigated. As the result, organic solvents such as NMP or ionomers deactivates Ni-Mo catalyst. To solve the problem, carbon support and carbon shell protection were adopted which showed protective effect to NMP and ionomers. Moreover, NiMo catalyst deactivation through ionomer activation was depressed through modified activation method, which suggested new direction to fabricating NiMo anode.