| 학회 | 한국재료학회 |
| 학술대회 | 2017년 가을 (11/15 ~ 11/17, 경주 현대호텔) |
| 권호 | 23권 2호 |
| 발표분야 | 6. 인공광합성 기술 개발 동향(Recent research trends in artificial photo-synthesis) |
| 제목 | Low Dimensional Catalysts for Electrochemical Fuel Production: Hydrogen and Ammonia |
| 초록 | Development of sustainable energy sources is an urgent issue to meet growing demand in world energy consumption. Among the various types of sustainable energy, hydrogen and ammonia are one of the most promising renewable energy sources with a high energy density. The discovery of efficient catalysts represents one of the most important and challenging issues for the implementation of photoelectrochemical (PEC) or electrochemical fuel production. A critical requirement for outstanding catalysts is not only an ability to boost the kinetics of a chemical reaction but also a durability against electrochemical and photo-induced degradation. Generally, precious metals, such as platinum, exhibit superior performance in these requirements; however, high cost of the precious metal is the biggest barrier to widespread commercial use. To address this critical and long-standing technical barrier, I have focused on an intense search for efficient, durable, and inexpensive alternative catalysts. My research have been concentrated on two subjects; (1) new possibilities of an atomic-scale catalyst as the efficient hydrogen evolution reaction (HER) catalyst, (2) the first report on the experimental electrochemical production of ammonia using Zirconium Nitride nanolayers grown by plasma enhanced atomic layer deposition. (1) Carbon-based nanomaterials have emerged as promising candidate catalyst for HER. The design of carbon-based catalysts represent an important research direction in the search for non-precious, environmentally benign, and corrosion resistant catalysts. Especially, graphene possesses excellent transmittance and superior intrinsic carrier mobility, thus there have been several attempts to use graphene as a catalyst. It has been reported that reduced graphene oxide containing catalytic active materials exhibited improved activity in HER, oxygen evolution reactions, and oxygen reduction reactions. In most cases, the role of carbon materials is limited to an electrical conducting substrate or a supporter that enhances the performance of other decorated active catalysts. There is no report of the application of monolayer graphene to hydrogen production. For the first time, I investigated new possibilities for monolayer graphene as an electrocatalyst for efficient HER and found that atomic defect engineering such as nitrogen doping through treatment with N2 plasma improved the catalytic activity. This study has also attracted particular interest to the materials and chemical society in that it has demonstrated the role of carbon-based catalysts with comprehensive electrochemical analysis as well as the first demonstration of monolayer graphene as the HER catalyst. (2) The reduction of nitrogen to produce ammonia has been attracting much attention as a renewable energy technology. Ammonia is the basis for many fertilizers and is also considered an energy carrier that can power internal combustion engines, diesel engines, gas turbines, and fuel cells. Traditionally, ammonia has been produced through the Haber-Bosch process, in which atmospheric nitrogen combines with hydrogen at high temperature (350-550℃) and high pressure (150-300 bar). This process consumes 1-2% of current global energy production and relies on fossil fuels as an energy source. Reducing the energy input required for this process will reduce CO2 emissions and the corresponding environmental impact. For this reason, developing electrochemical ammonia-production methods under ambient temperature and pressure conditions should significantly reduce the energy input required to produce ammonia. Metal nitrides are an interesting class of materials for electrochemical ammonia synthesis because they may be able to form ammonia through Mars-van Krevelen mechanism. In the mechanism, a surface N atom is reduced to ammonia, leaving behind a vacancy in the metal nitride surface. This vacancy can then be filled by dissolved N2, which can be further hydrogenated releasing ammonia and regenerating the metal nitride surface. Thus, the suggested might also cause a dynamic Faradaic redox reaction to occur at the surface of the electrode. Here, we are the first to report on the experimental electrochemical production of ammonia using Zirconium Nitride nanolayers grown by plasma enhanced atomic layer deposition. Upon applying a reducing potential in N2 purge electrolyte, ammonia was detected using a colorimetry assay test and FTIR spectroscopy. ZrN is an interesting material going forward to study for nitrogen reduction to ammonia due to its significant Faradaic efficiency in an aqueous system under ambient conditions. |
| 저자 | 심욱 |
| 소속 | 전남대 |
| 키워드 | Photoelectrochemical Cell; Hydrogen; Ammonia; Catalyst; ALD |
