Pd nanocatalyst supported on amine-functionalized mesoporous graphitic carbon nitride (Pd/NH 2 -mpg-C 3 N 4 ) was investigated for dehydrogenation of formic acid. The catalyst was analyzed and tested to investigate the effect of amine functionalization on hydrogen generation from formic acid. Pd nanocatalyst was dispersed uniformly on NH 2 -mpg-C 3 N 4 without agglomeration. The turnover frequency value of Pd/NH 2 -mpg-C 3 N 4 was 1870 h −1 , which was higher than that of Pd/mpg-C 3 N 4 because of the amine functionalization. The Pd/NH 2 -mpg-C 3 N 4 was also tested to investigate the effect of various reaction conditions (formic acid concentration, sodium formate concentration, and reaction temperature) on hydrogen generation from formic acid. Formic acid concentration negatively affected the catalytic activity, whereas sodium formate concentration positively affected it. Reaction temperature significantly affected the catalytic activity. The apparent activation energy of the Pd/NH 2 -mpg-C 3 N 4 catalyst was 60.7 kJ mol −1 , and a hydrogen generator with the catalyst exhibited high conversion efficiency at an elevated temperature. Consequently, a hydrogen generator with Pd/NH 2 -mpg-C 3 N 4 is suitable for polymer electrolyte membrane fuel cell systems. • Pd/NH 2 -mpg-C 3 N 4 is investigated for a hydrogen generator in a PEMFC system. • Amine functionalization significantly affects catalyst characteristics. • Pd/NH 2 -mpg-C 3 N 4 has superior selectivity and activity for dehydrogenation of formic acid. • Reaction conditions significantly affect the dehydrogenation of formic acid. • A hydrogen generator with Pd/NH 2 -mpg-C 3 N 4 exhibits high conversion efficiency.

Pd nanocatalyst supported on amine-functionalized mesoporous graphitic carbon nitride (Pd/NH 2 -mpg-C 3 N 4 ) was investigated for dehydrogenation of formic acid. The catalyst was analyzed and tested to investigate the effect of amine functionalization on hydrogen generation from formic acid. Pd nanocatalyst was dispersed uniformly on NH 2 -mpg-C 3 N 4 without agglomeration. The turnover frequency value of Pd/NH 2 -mpg-C 3 N 4 was 1870 h −1 , which was higher than that of Pd/mpg-C 3 N 4 because of the amine functionalization. The Pd/NH 2 -mpg-C 3 N 4 was also tested to investigate the effect of various reaction conditions (formic acid concentration, sodium formate concentration, and reaction temperature) on hydrogen generation from formic acid. Formic acid concentration negatively affected the catalytic activity, whereas sodium formate concentration positively affected it. Reaction temperature significantly affected the catalytic activity. The apparent activation energy of the Pd/NH 2 -mpg-C 3 N 4 catalyst was 60.7 kJ mol −1 , and a hydrogen generator with the catalyst exhibited high conversion efficiency at an elevated temperature. Consequently, a hydrogen generator with Pd/NH 2 -mpg-C 3 N 4 is suitable for polymer electrolyte membrane fuel cell systems. • Pd/NH 2 -mpg-C 3 N 4 is investigated for a hydrogen generator in a PEMFC system. • Amine functionalization significantly affects catalyst characteristics. • Pd/NH 2 -mpg-C 3 N 4 has superior selectivity and activity for dehydrogenation of formic acid. • Reaction conditions significantly affect the dehydrogenation of formic acid. • A hydrogen generator with Pd/NH 2 -mpg-C 3 N 4 exhibits high conversion efficiency.

본 연구에서는 다구찌 기법을 활용하여 외전형 모터의 방열 형상을 최적화하였다. 전산유체역학에 기반하여 회전자 케이스 외부에 위치한 외측핀과 내부에 위치한 리브 형상에 대해 최적화 설계를 수행하였다. 외측핀과 내부 리브 각각에 대해 4개의 설계 인자를 도출 후, 실험계획법을 적용하여 직교 배열표를 도출하였다. 직교 배열표를 바탕으로 수치해석을 수행한 결과, 케이스 외부의 외측핀 형상이 방열 성능에 가장 큰 영향을 미쳤고 케이스 내부의 리브 블레이드 형상과 이중 블레이드 위치가 방열 성능에 가장 큰 영향을 미쳤다. 최종 최적화 형상은 기존 형상에 비해 모터 내부 베어링의 온도가 약 6℃ 감소하였다. 따라서 본 연구에서 개발된 방열 형상 및 최적화 설계 방법론은 향후 타 전자제품군에 널리 활용될 수 있다.

In this study, an effective catalyst reuse strategy for formic acid hydrogen generators was developed. Characterization and performance tests were conducted using Pd/mpg-C3N4 and Pd/NH2-mpg-C3N4 catalysts to investigate the effect of amine functionalization. Amine functionalization positively affected the catalyst characteristics and activity. The reusability of the catalyst was evaluated through repeated hydrogen generator tests. The experimental and analytical results indicated that re-functionalization significantly improved the catalyst reusability compared with washing. Hence, the re-functionalization can effectively improve the practicality of formic acid hydrogen generators.

In this study, a fuel cell system for future defense unmanned vehicles was designed and validated. A Co/Al2O3-Ni foam catalyst for NaBH4 hydrolysis was characterized using several analytical methods. A NaBH4 hydrogen generation system with the Co/Al2O3-Ni foam catalyst continuously generated hydrogen at elevated reaction temperatures. The fuel cell system with the NaBH4 hydrogen generation system was designed and tested. The performance of the fuel cell system was comparable to that of the fuel cell system using pure hydrogen. Therefore, the fuel cell system with the NaBH4 hydrogen generation system is a suitable power source for future defense unmanned vehicles owing to its easy refueling and simple system.

Co/Al2O3 nanopowder was used as a catalyst to investigate the effect of catalyst support, reduction temperature, sodium borohydride (NaBH4) concentration, sodium hydroxide (NaOH) concentration, and reaction temperature on the characteristics of NaBH4 hydrolysis. The Co/Al2O3 nanopowder showed a high catalytic activity among various catalysts. Catalyst reduction at 250℃ exhibited a relatively good activity. The activity decreased with an increase in the NaBH4 concentration. Conversely, the activity increased and then decreased with an increase in the NaOH concentration. Additionally, the activity increased with an increase in the reaction temperature. The value of apparent activation energy was 40.81 kJ/mol, which was lower than the other Co-based catalysts. Thus, Co/Al2O3 nanopowder catalyst can be widely used for NaBH4 hydrolysis owing to its superior catalytic activity.