| 摘要: | 在追求具有成本效益的儲能材料以及可再生能源的過程中，電化學水分解系統是個可行的解方，因陰極反應生成的氫氣被視為是極具潛力的清潔能源。然而，陽極緩慢的析氧反應 (OER) 阻礙了其應用。因此本研究利用生物質的選擇性氧化取代陽極析氧反應，生成高附加價值的產物，不僅可改善現今過度依賴石化燃料的問題，同時也有效利用再生資源。
實驗使用木質素衍生物5-羥甲基糠醛 (HMF) 作為反應物，藉此生成目標產物2,5-呋喃二甲酸 (FDCA) ，由FDCA聚合而成的聚乙烯 2,5-呋喃二甲酸酯 (PEF) 樹脂有望成為聚對苯二甲酸乙二醇酯 (PET) 之替代品。我們以水熱法和爐管磷化熱處理在泡沫鎳 (Nickel foam) 上原位 (in situ) 合成了三維分層結構的NiCoP，並透過裝載CoFe層狀雙氫氧化物 (Layered double hydroxides, LDHs) ，形成n-n型異質結構的CoFe LDH@NiCoP/NF的電觸媒，該異質接面促進表面電子重排，不僅有效改善電化學性能，還提高了催化劑的穩定性。我們進一步以調節Ni-Co前驅液濃度與水熱沉積時間做為變因，找出合成CoFe LDH@NiCoP/NF的最適化條件。最後摻雜適量的鉬 (Mo) 元素，可以有效調節NiCoP的電子結構，從而增加活性位點。
結果顯示用前驅液鎳與鈷莫爾比為1比1，水熱6小時製備的CoFe@NiCoP-6h，在HMF選擇性氧化反應有最佳表現。與未裝載CoFe LDH的NiCoP相比，施加偏壓1.50 V vs. RHE 並反應6小時後，FDCA的選擇率從79.73 % 提升至83.72 %，產率也從64.51 %增加至79.91 %。不僅如此，摻雜2.5 mole % Mo的CoFe@2.5 Mo-NiCoP-6h，HMF轉化率、FDCA產率和選擇率甚至分別達到100 %、98.34 %和98.34 %。綜上所述，作為HMF選擇性氧化的電催化劑，CoFe LDH@Mo-NiCoP/NF是十分具潛力的選擇。;In the pursuit of cost-effective energy storage materials and renewable energy, electrochemical water splitting systems present a viable solution, as the hydrogen generated by the cathode reaction is a promising clean energy source. However, the slow oxygen evolution reaction (OER) at the anode hampers its application. To address this, our study employs the selective oxidation of biomass to replace the anode OER, generating high value-added products. This approach not only mitigates the current over-reliance on fossil fuels but also effectively utilizes renewable resources.
In this study, we use the lignin derivative 5-hydroxymethylfurfural (HMF) as the reactant to produce 2,5-furandicarboxylic acid (FDCA). FDCA can be polymerized into polyethylene 2,5-furandicarboxylate (PEF) resin, which is a potential substitute for polyethylene terephthalate (PET). We synthesized NiCoP with a three-dimensional layered structure in situ on nickel foam using a hydrothermal method followed by furnace tube phosphating heat treatment. We then loaded CoFe layered double hydroxides (LDHs) to form an n-n type heterostructure CoFe LDH@NiCoP/NF electrocatalyst. This heterojunction promotes surface electron rearrangement, enhancing both the electrochemical performance and stability of the catalyst. We optimized the synthesis conditions of CoFe LDH@NiCoP/NF by adjusting the Ni-Co precursor solution concentration and hydrothermal deposition time. Additionally, doping with an appropriate amount of molybdenum (Mo) effectively adjusted the electronic structure of NiCoP, increasing active sites.
Our results demonstrate that CoFe@NiCoP-6h, prepared with a nickel-to-cobalt molar ratio of 1:1 and hydrothermal treatment for 6 hours, exhibited the best performance in the HMF selective oxidation reaction. Compared to NiCoP without CoFe LDH, the FDCA selectivity increased from 79.73 % to 83.72 %, and the yield from 64.51 % to 79.91 % after applying a constant voltage of 1.50 V vs. RHE for 6 hours.
Remarkably, for CoFe@2.5 Mo-NiCoP-6h doped with 2.5 mole % Mo, the HMF conversion rate, FDCA yield, and selectivity reached 100 %, 98.34 %, and 98.34 %, respectively. In summary, CoFe LDH@Mo-NiCoP/NF shows great promise as an electrocatalyst for the HMF selective oxidation reaction. |
