用計算化學方法研究 Nafion 修飾銅電極之 CO 耦合機制

Abstract

本論文探討了全氟-1-戊烷磺酸鈉修飾的Cu(111)表面在Nafion等磺酸全氟聚合物修飾下的電化學電極，以模擬C-C耦合反應。通過分子動力學模擬，研究了不同濃度的全氟-1-戊烷磺酸鈉和不同水量對電極表面修飾的影響。結果顯示，高濃度的全氟-1-戊烷磺酸鈉可能導致部分分子在水層的作用下與電極表面接觸，但隨著濃度降低，這種情況得到改善。進一步使用密度泛函理論（DFT）模擬了電化學電極表面的OC-CO和OC-COH耦合反應。研究發現，質子化的*COH較容易與*CO進行耦合反應，且OC-CO耦合反應的能從1.87 eV降至OC-COH耦合反應的0.68 eV。但OC-COH耦合反應需要先經歷能為1.52 eV的*CO質子化反應，該反應可以通過偏壓驅動的質子轉移反應（PCET）實現。除此之外進行了真空電極表面*CO和*COH的擴散模擬，並研究了吸附物相遇方向對耦合反應的影響。結果顯示在真空電極表面*CO和*COH的擴散能皆很小，分別為0.001 eV和0.144 eV。當OH朝向*CO時，*CO可以輕易地靠近*COH，而當靠近的*COH發生轉向使得OH鍵朝向*CO的反向時，OC-COH耦合反應之能壘可以從0.73 eV下降至0.53 eV，但反應能卻從0.20 eV上升至0.29 eV。DOS和COOP分析表明與混層軌域能量和程度有關。本研究針對全氟-1-戊烷磺酸鈉修飾的電化學電極表面中的C-C耦合反應進行了深入的探討。研究結果揭示了修飾條件和反應機理之間的關係，為設計和優化磺酸全氟聚合物修飾的電化學電極提供了有價值的見解。這些發現對於促進有機合成反應和電催化領域的發展具有潛在的應用價值。Examining Cu(111) surface modified with Sodium perfluoro-1-pentanesulfonate (NaPFPS) alongside sulfonic acid perfluorinated polymers reveals insights into simulating C-C coupling reactions. Molecular dynamics simulations explored the impact of NaPFPS concentration and water content on electrode surface modification. Higher NaPFPS concentrations exhibited partial electrode contact, with improvements noted as concentrations decreased.Density functional theory (DFT) calculations simulated OC-CO and OC-COH coupling reactions on the modified surface. Protonated *COH readily coupled with *CO, with OC-CO coupling energy decreasing from 1.87 eV to 0.68 eV for OC-COH coupling. Prior *CO protonation (1.52 eV) facilitated the reaction via bias-driven proton-coupled electron transfer (PCET).Diffusion simulations of *CO and *COH on the gas/solid electrode interface investigated the impact of adsorbate encounter direction. Minimal diffusion energies were observed (0.001 eV for *CO, 0.144 eV for *COH). *CO easily approaches *COH when OH approaches, but when *COH reorients, reversing the OH bond's orientation toward *CO, the energy barrier for OC-COH coupling decreases from 0.73 eV to 0.53 eV, with the reaction energy increasing from 0.20 eV to 0.29 eV. This study provides insights into C-C coupling reactions on Cu(111) surfaces modified with NaPFPS. It elucidates the relationship between modification conditions and reaction mechanisms, aiding the design and optimization of electrochemical electrodes with sulfonic acid perfluorinated polymers. The findings have potential applications in electrocatalysis.