二氧化鈦奈米管負載金/鉑核殼結構應用於光催化水分解製氫

Abstract

氫為一乾淨的、可再生的且具高能量密度燃料，對於目前全球能源經濟的需求和實現環境友善的目標並具有取代石化燃料的潛力。在過去十年中，採用金屬/半導體之光電化學系統將太陽能轉換成氫能的光催化水分解反應是目前最具有開發價值的能源轉換反應。目前，利用鉑等貴金屬催化劑驅動太陽能將水裂解成氫氣的反應是最有效率的，然而因其成本非常高且相當稀少，而大大限制了大規模綠色能源的發展，故對於現今的科學家們仍然是具有相當大的挑戰性。 在本研究中，我們合成了具有低生產成本和高催化效率的光催化水分解複合材。透過簡單的電化學陽極氧化方法合成自組裝之二氧化鈦奈米管，並結合簡便的化學還原方法製備出具有良好的光吸收性能之金與鉑核殼結構奈米粒子，並成功應用於高效能且穩健的太陽能驅動產氫反應系統。此外，透過調控和設計金與鉑核殼結構奈米粒子，我們能更進一步優化金核金屬的奈米顆粒尺寸及鉑金屬殼的厚度，並有系統性地提升太陽能光轉化氫能的催化反應效率。此優異的催化性能源自於具有強烈光吸收性能的金核金屬本身之可調性表面電漿共振效應並結合鉑殼金屬光催化產氫性能與具有一維材料所擁有的優異電子傳遞特性之二氧化鈦奈米管所致。二氧化鈦奈米管負載金與鉑核殼結構奈米粒子亦呈現出其於長時間反應的光催化水分解產氫穩定性能，並使此金屬/半導體異質結構光催化材料對於太陽光能轉化氫能的系統表現出具有取代石化燃料的潛在能力。

Hydrogen, a clean, renewable, and high-energy density energy fuel, is a promising sustainable alternative for the global energy demand and achieving an environmentally friendly fuel economy. Utilizing an integrated photoelectrochemical (PEC) system based on metal/semiconductor materials to directly convert solar to hydrogen via water splitting is one of the most promising approaches in the last decade. Althougth platinum and other noble metals were efficiency for solar-driven hydrogen evolution reaction (HER), but the highly cost and scarcity greatly limit their large scale development of green energy is challenging and demanding tasks for today's scientists. In this study, we synthesized high efficient and low-cost HER photoelectrocatalysts including self-aligned TiO2 nanotubes (TiO2 NTs) via a facial electrochemical anodization method and light absorber Au@Pt core/shell nanoparticles via facile chemical reduction method, which could produce an efficient and robust PEC catalysts for solar-driven HER. Moreover, by optimizing the size of Au core particles and thickness of Pt shell, we are able to achieve an optimal Au@Pt core/shell nanoparticles structure and futher improve the overall solar conversion hydrogen efficiency. This superior performance can be attributed to the significant improvement in light harvesting properties from surface plasmon resonance effect of Au core nanostructure as well as the optimized interface between the shell Pt nanostructure catalysts and one-dimensional TiO2 NTs substrate. Outstanding HER stability was also demonstrated over long-term operation, suggesting these Au@Pt-TiO2 NTs heterostructures are promising fossil fuel alternatives for PEC catalysts of solar-driven hydrogen production.