具蛋黃-蛋殼結構之CoFe-MIL@CoNiFe-LDH與Fe3O4@NiFeSe2奈米棒作為高效析氧反應電催化劑之研究

Abstract

為滿足對具成本效益的水分解技術的迫切需求，亟需兼具高內在活性與長期穩定性的析氧反應(OER)電催化劑。本研究提出一種金屬有機框架（MOF）衍生的自犧牲策略以構建具有中空蛋黃-蛋殼結構的奈米棒，包括：(i)外層為CoNiFe層狀雙氫氧化物（LDH）、內核為CoFe-MIL的結構（CoFe-MIL@CoNiFe LDH YSNR），以及(ii)外層為NiFeSe2包覆Fe3O4的結構（Fe3O4@NiFeSe2 YSNR）。這種層級化中空結構可最大化電化學可接觸表面積、縮短離子擴散路徑，並穩定催化劑的活性相。在1.0 M KOH中，CoFe-MIL@CoNiFe LDH YSNR於過電位275 mV時可達10 mA cm⁻2的電流密度，Tafel斜率為94.8 mV dec⁻1；而Fe3O4@NiFeSe2 YSNR則於過電位260 mV時達相同電流，Tafel斜率為70.7 mV dec⁻1，均優於市售RuO2。恆電流測試顯示50小時內施加電位漂移小於4.5%，證明其優良的穩定性。電化學毒化實驗與去鐵對照實驗指出Ni/Co為主要活性位點，而Fe則透過協同電子效應提升催化表現。本研究證實，以MOF模板為導向的蛋黃-蛋殼合成策略為構建多金屬電催化劑的有效途徑，並為次世代高效析氧材料的設計提供了重要原則。

Meeting the urgent demand for cost effective water splitting technologies requires oxygen evolution electrocatalysts that couple high intrinsic activity with long term durability. Here we devise a metal-organic framework derived, self sacrificial strategy to construct yolk-shell nanorods comprising (i) a CoNiFe layered double hydroxide shell surrounding a CoFe MIL core (CoFe MIL@CoNiFe LDH YSNR) and (ii) a NiFeSe2 shell enclosing Fe3O4 (Fe3O4@NiFeSe2 YSNR). The hierarchical hollow architecture maximizes electrochemically accessible surface area, shortens ion diffusion pathways and stabilizes the active phase. In 1.0 M KOH, CoFe MIL@CoNiFe LDH YSNR attains a current density of 10 mA cm-2 at an overpotential of 275 mV with a Tafel slope of 94.8 mV dec-1, whereas Fe3O4@NiFeSe2 YSNR delivers the same current at 260 mV and 70.7 mV dec-1, surpassing commercial RuO2. Chronopotentiometry shows <4.5 % applied potential drift over 50 h, confirming great operational stability. Electrochemical poisoning and Fe free controls pinpoint Ni/Co sites as the primary OER centres, while Fe plays a synergistic electronic role. This work establishes MOF templated yolk-shell engineering as a powerful route to multi metallic electrocatalysts and provides design principles for next-generation oxygen-evolution materials.