| 摘要: | 由於能源危機和環境污染問題，所以再生能源的發展便為相當重要。其中，氫氣因為燃燒時不產生碳排放而被視為潔淨能源，而電解水產氫的研究也因此備受關注。然而在鹼性環境中，陰極的析氫反應(hydrogen evolution reaction, HER)受到緩慢動力學的影響，導致較高的過電位，而在酸性環境中，觸媒穩定度較差。另外，由於海水資源豐富，透過海水電解生產氫氣被視為一永續且環保的策略。因此，設計高活性、穩定性的觸媒是發展海水和淡水產氫技術的關鍵。
釕(Ru)具有與Pt相當的氫鍵結強度，然而，其對氫吸附能強，所以需要降低氫的吸附能才能改善產氫，而硼化可有效調節Ru的電子結構，使其位於火山圖中更靠近Pt。在本研究中，透過NaBH4 還原法製備出具有高HER活性及高穩定性的RuB基觸媒，而微量Pt的添加不僅能增加觸媒在0.5 M H2SO4電解液中的活性，還可促進其長時間測試的結構穩定性。此外，Co可以提升觸媒在鹼性模擬海水(1 M KOH+3.5wt% NaCl)中的水解能力，值得注意的是，RuB-Pt/C及RuB-CoPt/C分別在酸性及鹼性模擬海水電解液中表現出色的穩定性及活性，在電流密度10 mA/cm2 的過電位分別為20 及15 mV, Tafel 斜率為11及23 mV dec-1，質量活性為7803 及1194 mA/mg Ru+Pt，並且經過5000圈循環的穩定度測試後仍保有優異的HER性能。
另一方面，透過感應耦合電漿放射光譜儀(Inductively coupled plasma optical emission, ICP-OES)分析穩定度測試後的電解液，結果顯示添加Co、B和Pt可以防止或減少Ru觸媒在酸及海水電解液中的溶解，從而提高觸媒的結構穩定性。在酸性中的穩定度也透過原位X射線吸收光譜(in-situ X-ray absorption spectroscopy, in-situ XAS)分析，觸媒的主要活性位點為Ru-B，且添加Pt能顯著增強觸媒結構的穩定性，使其在酸性電解液中展現出卓越的HER性能。此外，也透過CO 剝離測試(CO-stripping)結果顯示Co的添加有利於海水的解離。本研究製備出低貴重金屬含量且在酸性及鹼性模擬海水電解液中具高HER性能的RuB基觸媒，並了解優異HER性能的促進機制，提供了製備高活性HER酸及海水觸媒的思維。;Due to the energy crisis and environmental pollution issues, the development of renewable energy is of paramount importance. Hydrogen is regarded as clean energy because it does not produce carbon emissions when burned and hydrogen production through water electrolysis has attracted much attention. However, the hydrogen evolution reaction (HER) at the cathode in alkaline environments is hindered by sluggish kinetics, resulting in higher overpotentials, whereas in acidic environments, the stability of catalysts is a concern. Additionally, given the abundance of seawater resources, producing hydrogen through seawater electrolysis is a sustainable and eco-friendly strategy. Therefore, designing catalysts with high activity and stability is crucial for advancing hydrogen production technologies from both seawater and freshwater.
Ru possesses hydrogen bonding strength comparable to Pt, yet its strong hydrogen adsorption energy necessitates reduction to improve HER performance. Boronization can effectively tune the electronic structure of Ru, aligning it closer to Pt in the volcano plot. In this study, RuB-based catalysts with high noble metal utilization, and high HER activity and stability are synthesized using the NaBH4 reduction method, and the addition of low amounts of Pt not only enhances the catalyst′s activity in 0.5 M H2SO4 electrolytes but also promotes structural stability during long-term test. Additionally, Co improves the catalyst′s hydrolysis ability in alkaline simulated seawater (1 M KOH + 3.5wt% NaCl). Notably, RuB-Pt/C and RuB-CoPt/C exhibit excellent stability and activity in acidic and alkaline simulated seawater electrolytes, with overpotentials of 20 and 15 mV at a current density of 10 mA/cm2, Tafel slopes of 11 and 23 mV dec-1, and mass activities of 7803 and 1194 mA/mgRu+Pt, respectively. Both catalysts maintain superior HER performance after 5000 cycles of stability test.
Additionally, inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis of the electrolytes after ADT reveals that the addition of Co, B, and Pt can effectively prevent or mitigate the dissolution of Ru catalysts in acidic and seawater electrolytes, thereby enhancing the structural stability of catalysts. The stability under acidic conditions is further explored using in-situ X-ray absorption spectroscopy (in-situ XAS), identifying Ru-B as the predominant active site, with Pt addition significantly promoting catalyst structural stability and resulting in exceptional HER performance in acidic electrolytes. Furthermore, CO-stripping test indicates that the addition of Co facilitates seawater dissociation. This study introduces RuB-based catalysts with low noble metal content and high HER performance in both acidic and alkaline simulated seawater electrolytes, shedding light on the mechanisms driving their superior HER performance and providing insights into the development of highly active HER acid and seawater catalysts. |
