利用定向電場增強二維材料邊緣的電化學活性

Abstract

二维材料邊緣作為電化學催化系統具有廣闊的前景，但其催化性能仍然不及貴金屬。我們展示了利用定向電場(OEFs)增強二维材料邊緣電化學活性的潛力。通過原子級別的工程設計，我們在氟化石墨烯/石墨烯/二硫化鉬異質結構(fluorographene/graphene/MoS2 heterojunction)的邊緣產生了強力且局部化的電場，並通過模擬和空間分辨光譜進行表徵。邊緣定向外部電場的獨特靜電特性顯著提高了邊緣與電解質之間的異質電荷傳輸速率，達到了兩個數量級的提升，這一點通過阻抗光譜(EIS)得到了驗證。第一性原理計算表明，這一改進源於電場誘導的反應物吸附能降低。我們將這種定向電場增強的邊緣反應應用於氫氣析出反應(HER)，並觀察到極佳的電催化效果，這體現在塔菲爾斜率降低了30%，以及2D材料達到了前所未有的轉換頻率(turnover frequency)。我們的發現為未來複雜反應中調整2D材料的催化特性開闢了一條新途徑。

Two-dimensional (2D) material edges have shown promise as electrochemical catalysts, but their performance has not yet matched that of noble metals. In this study, we explore the use of oriented electric fields (OEFs) to boost the electrochemical activity of 2D material edges. We engineered the edge of a fluorographene/graphene/MoS2 heterojunction nanoribbon at the atomic level, creating powerful and localized OEFs. These fields were analyzed using simulations and spatially-resolved spectroscopy. The unique electrostatic properties of the fringing OEF led to a hundredfold increase in the heterogeneous charge transfer rate between the edge and the electrolyte, as shown by impedance spectroscopy. Ab-initio calculations suggest that this improvement stems from a field-induced reduction in reactant adsorption energy. We applied this OEF-enhanced edge reactivity to hydrogen evolution reactions (HER), achieving exceptional electrochemical performance. This was evidenced by a 30% decrease in Tafel slope and a record-breaking turnover frequency for 2D materials. Our research paves the way for fine-tuning the catalytic properties of 2D materials for future complex reactions.