燃料電池是利用氫及氧的化學反應，氧氣則由陰極進入電池，在催化劑作用下，氫質子、氧及電子，發生反應形成水分子。由於燃料電池是經由利用氫及氧的化學反應，產生電流及水，並不會如石化燃料燃燒排放污染物，符合環境友善、潔淨能源等觀念。而燃料電池陰極氧氣還原反應為限制因子，白金觸媒雖然具有良好的催化活性，但受限於觸媒價格昂貴、觸媒毒化等問題。本研究中，我們使用生物質廢物合成非貴重金屬催化劑，並選擇過渡金屬鹽和氫氧化鉀分別作為催化劑和活化劑，碳源經過水熱180°C碳化後，以通過微波800 W進行10分鐘活化石墨化，再以酸洗去鉀離子，並在NH3氣氛下以微波800 W進行摻氮，製備出核殼(core-shell)結構的M-N-C催化劑。相較於木質素，纖維素樣品具較多鐵氮活性位置以及促進質傳的中孔結構，因此有較好的氧氣還原活性(Eonset= -0.05 V)。然而Fe/Co比例1:1合金不僅具有優異的活性(Eonset= -0.06 V)，同時展現更佳的穩定性，在10000秒的循環測試後，維持原先73%的電流值。以生質廢棄物(甘蔗)作為碳源並以Fe/Co比例1:1合成陰極觸媒，通過測試觸媒展現IV型吸脫附曲線，表明中孔結構的存在，透過電子顯微鏡可以清楚的觀察到核殼結構及合金的形成。結果顯示，其具優異的ORR催化活性(Eonset = -0.06 V)及近四電子傳輸，並且能抵抗甲醇的毒化。此外，我們通過微波加熱系統提供一個快速且節能的方法來合成M-N-C觸媒。

Fuel cell is a device converting the chemical energy into electricity through an electrochemical reaction. At the cathode, the hydrogen ions, electrons, and oxygen are reacted and produced water. Compared to fossil fuels, the fuel cell only produce electricity and water without the emission of pollutants, so the fuel cell meets the concepts of environmental friendliness and clean energy. However, the sluggish kinetics of the cathodic oxygen reduction reaction and the high cost, poor durability of noble metal catalysts limit the large-scale commercial applications. In this study, we recover lignocellulose biomass to synthesize non-noble metal catalysts, and choose transition metal and potassium hydroxide as catalysts and activation agents, respectively. The samples after carbonization are activated by 800 W microwave radiation for 10 min. The obtained biochars are washed with 0.5 M HCl to remove K ions. For nitrogen doping, a post-treatment is performed by using microwave radiation with 800 W under NH3 atmosphere. By microwave irradiation, we produced core-shell structured M-N-C catalysts. Compared with lignin, cellulose-derived catalysts display superior ORR catalytic activity (Eonset=-0.05 V) due to more Fe-Nx active sites and mesopore structure which can promote mass transport. Moreover, FeCo alloys with ratio (Fe:Co = 1:1) samples not only show a comparable activity but also exhibit a better stability and maintain 73% of current density after 10000s of operation. In terms of biomass waste (sugarcane), the catalysts synthesized by Fe/Co (1:1) encapsulated with N doped carbon layers show a type IV adsorption-desorption isotherm, indicating the existence of mesopores. The formation of core-shell structure of FeCo alloys can be observed as evidenced by TEM. Meanwhile, the SC-Fe5Co5 exhibits excellent ORR catalytic activity (Eonset up to −0.06 V) through four-electron pathways (n≒3.9) in the alkaline electrolyte and excellent resistance to methanol crossover. Moreover, the synthesis process via a microwave-assisted treatment could provide a facile and energy-effective route to construct core-shell structured metal-N-C.

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