為應對氣候變遷與實現淨零碳排目標，開發潔淨能源成為全球重點議題。氫氣因其高能量密度與零碳排特性，成為重要的未來綠色能源之一。目前常用的蒸氣重組製氫法伴隨高碳排，而電催化水分解則提供一種更環保的產氫方式，具備條件可控與工業可行性。該反應包含析氫與析氧兩個半反應，關鍵在於開發高效率、低成本且穩定的電催化觸媒。碳化物與非貴金屬過渡金屬具備優異潛力，異質結構的引入更可提升反應活性與界面動力學，成為研究焦點。
本研究運用快速溶劑燃燒法，將金屬前驅物均勻負載於泡沫鎳基材上，再經高溫還原合成出金屬與碳化物異質結構型觸媒。材料設計上，針對HER製備Mo2C@NM，OER製備Mo2C@FNM，利用XRD與TEM的材料鑑定證實兩種材料具有異質結構。在HER中Mo¬2C@NM於電流密度10與500 mA cm⁻² 時僅需37與169 mV的過電位；Mo2C@FNM於OER中達到電流密度10 與500 mA cm⁻² 只需218 和303 mV。電化學測試的結果顯示兩種觸媒皆展現出優異的催化活性，與單一成分對照組比較後可以發現異質結構觸媒性能明顯提升。此外，Mo2C@NM的Tafel斜率為74.6 mV dec-1，推測速率決定步驟可能是由Volmer和Heyrovsky兩種反應步驟的組合。Mo2C@FNM表現同樣優異，達到電流密度10 與500 mA cm⁻² 只需218 和303 mV。與對照組相比進一步降低OER Tafel斜率至32.7 mV dec-1，最低的Tafel斜率表示有最佳的OER催化有效度。
為了測試觸媒於陰離子交換膜水電解器系統中的適配性，以Mo2C@NM/NF、Mo2C@FNM/NF和商用陰離子交換膜PiperION組成膜電極組進行系統測試。在2 V下，電流密度高達2645 mA cm⁻²，展現極高催化效率。長效測試於500 mA cm⁻² 的電流密度下進行50小時，其電位僅衰退2%，證明其於鹼性環境下具備良好穩定性。因此，綜合材料設計、電化學特性與實際系統測試，顯示本研究所開發之異質結構觸媒兼具高效、低成本與商業化潛力。

To address the issue of climate change and to achieve the goal of net-zero emissions by 2050, developments of clean energies have become a global priority. Hydrogen, with its high energy densities and zero carbon emissions when releasing energies, is considered one of the most promising green energy carriers for the future. Currently, steam methane reforming is the most widely used industrial hydrogen production process, but it results in significant CO2 emissions. On the contrary, electrochemical water splitting offers a more environmentally friendly hydrogen production route with controllable conditions and industrial scalability. Water electrolysis consists of two half-reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. The key to improve efficiency lies in developing cost-effective, efficient and stable electrocatalysts. Non-precious transition metal carbides and non-precious transition alloys exhibit excellent catalytic potentials, whereas heterostructured catalysts have recently attracted great interests because of their ability to enhance surface reactivity and interfacial kinetics.
In this study, a rapid solution combustion method was developed to uniformly load metallic precursors onto a nickel foam (NF) substrate, followed by thermal reduction to synthesize carbide/alloy heterostructured catalysts. In terms of material design, Mo2C@NM (NM=NiMo) was prepared for the hydrogen evolution reaction (HER), and Mo2C@FNM (FNM=FeNiMo) for the oxygen evolution reaction (OER). Structural characterizations using X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of heterostructures in both catalysts. For HER, Mo2C@NM required only 37 and 169 mV of overpotentials to achieve current densities of 10 and 500 mA cm⁻², respectively. In the OER process, Mo2C@FNM achieved 10 and 500 mA cm⁻² at overpotentials of just 218 and 303 mV, respectively. Electrochemical characterizations demonstrated that both catalysts exhibited excellent catalytic activities. Compared to their single-component counterparts, the heterostructured catalysts showed significantly enhanced electrocatalytic performances. Moreover, Mo2C@NM exhibited a Tafel slope of 74.6 mV dec⁻¹, suggesting that the rate-determining step likely involves a combination of the Volmer and Heyrovsky steps. Mo2C@FNM also delivered outstanding OER performances, achieving current densities of 10 and 500 mA cm⁻² at 218 and 303 mV, respectively, and a low OER Tafel slope of 32.7 mV dec⁻¹. This exceptionally low Tafel slope indicates highly efficient OER kinetics.
To evaluate the applicability of the synthesized catalysts in anion exchange membrane water electrolyzer systems, membrane electrode assemblies (MEAs) were fabricated using Mo2C@NM/NF as the cathode and Mo2C@FNM/NF as the anode. The AEMWE thus assembled delivered a high current density of 2,645 mA cm⁻² at 2.0 V, demonstrating outstanding catalytic efficiency. Moreover, a long-term durability test conducted at 500 mA cm⁻² for 50 hours, experiencing only a 2.0% voltage increase, indicating excellent chemical stability under alkaline conditions. Overall, this study highlights the potential of heterostructured electrocatalysts for high-performance, low-cost, and scalable water-splitting applications.