利用原子沉積技術表面改質金屬有機物框架之衍生物用於水分解反應

Abstract

近年來，金屬有機骨架材料（MOFs）因其卓越的孔隙性能和極高的表面積，在水分解領域受到廣泛關注，常被用作水分解電極的材料或電極前驅物。本研究針對此課題，運用原子層沉積技術（ALD）成功沉積氧化錫層於改善三元金屬鎳鈷鐵MOF-74的水解性能。經實驗驗證，我們觀察到經ALD處理的MOFP/SnO2/NF樣品表現出優異的電化學性能，其析氧反應（OER）的過電位僅為243 mV，同時具有卓越的析氫反應（HER）活性，其過電位僅為80 mV。這優越的OER表現歸因於ALD沉積的氧化錫層的影響。X射線光電子能譜（XPS）分析結果表明，氧化錫層的引入可調節MOF中金屬的電子環境，提高金屬的價數，從而改善OER反應的效能。此外，在HER方面，ALD氧化錫層為反應提供更多的水分子吸附位置。因而提升水分解效率。為了實現ALD製程的最佳化與時間節省，我們通過調整ALD週期數量，控制了氧化錫層的厚度。研究結果表明，在進行了15個ALD循環後，僅需10分鐘的ALD處理，即可達到最佳的改善水分解反應效果。

Metal oxide-modified metal-organic frameworks (MOFs) have recently garnered attention as versatile precursors for fabrication of functional MOF derivatives for use as electrocatalysts for water electrolysis. In this study, we employed atomic layer deposition (ALD) to modify the surface of electrocatalysts based on phosphorized NiCoFe-MOF-74 and nickel foam (NF) with SnO2. The resulting MOF/SnO2/NF composite electrocatalysts exhibited exceptional performance in both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) of alkaline water electrolysis, with low overpotentials of 243 mV and 80 mV at 10 mA/cm2, respectively, and 318 and 162 at 100 mA/cm2, respectively. The remarkable OER performance was attributed to the SnO2 modification layer regulating the electro-chemical environment of MOF. X-ray photoelectron spectroscopy (XPS) analysis provided evidence of electron transfer from MOF to the SnO2 modification. On the other hand, the enhanced HER performance was attributed to the synergistic effects of the SnO2 modification and the metal sites of the MOF, which facilitated the adsorption of water species on the catalyst's surface. By examining SnO2 modification layers deposited with various numbers of ALD cycles, we found that 15 cycles yielded the lowest overpotentials while also allowing for relatively short processing time. The findings of this work provide valuable insights for the development of high-performance MOF-based electrocatalysts.