| 초록 |
Ammonia is considered as an indispensable source of energy in terms of an internal combustion engine and hydrogen source for fuel cell systems. Ammonia is not only used as fuel but also as a raw material of fertilizers. However, the conventional Haber-Bosch process for making ammonia needs lots of energy source and sophisticated instruments necessitating conditions of 150 atmospheric pressure and 500oC to break the triple bond of dinitrogen. Further, it consumes 1-2% of current global energy production and relies on fossil fuels as an energy source, which paves the way for emission of CO2 gas causing environmental pollution. So, we need to reduce the consumption of energy to nitrogen reduction and produce high pure ammonia. And ammonia production using the electrochemical method is able to make high pure ammonia, and it is necessary to build up studies of catalyst for improving performance. In this study, we have researched the electrochemical nitrogen reduction reaction of the tungsten carbide-based material at ambient conditions. Tungsten carbide has been used to counter electrode because it has excellent stability and high electric conductivity, but it has not been used as nitrogen reduction reaction yet. In addition, it has been pointed out the difficulty that a high temperature is required to design various shapes of catalyst electrode. To overcome this limitation, we fabricated tungsten carbide electrode by using a 3D printer to maximize a surface area and added Cobalt (Co) element to increase moldability and compared with electrochemical ammonia yield by modulating the Co content. Among them, we selected 10% Co in tungsten carbide (WC-10Co) and tried to bulk electrolysis from -1.0V to -1.5V (vs. Hg/HgO, 0.1M KOH) at 0.1V interval in N2 purged for nitrogen reduction at ambient condition. The results were 1.133×10-10 mol s-1 cm-2 of ammonia yield at -1.1V (vs. Hg/HgO, 0.1M KOH) and 3.26% of faradaic efficiency. Therefore, 3D printing based catalyst materials have a lot of potential for the electrochemical reaction such as nitrogen reduction reaction. |
