Structural evolution and modification of highly active and durable TiO2@Pt core-shell catalyst for oxygen reduction reaction

• Main Authors: Ya-Shiuan Heh, 賀雅萱
• Other Authors: Bing-Joe Hwang
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/78tts8

碩士 === 國立臺灣科技大學 === 化學工程系 === 107 === Structural evolution and modification of new nanostructured platinum-based oxygen reduction reaction catalysts are the objectives of this study. In our previous work, unsupported core-shell TiO2@Pt particles were proposed as a model catalyst could generate efficient ORR catalyst. Although TiO2@Pt particles derived from the photo-deposition method could have a completely covered Pt shell structure, and achieved reasonable ORR catalytic activity. In this work, a well-controlled feeding method using a syringe pump for Pt precursor is introduced to achieve uniform and thin Pt photodeposition on TiO2 particle. High-resolution transmission electron microscopy (HRTEM) and elemental mapping images showed that the complete Pt shell on TiO2 core was formed, and the thickness of Pt shell was around 2 nm as a result of more precise control over Pt growth. The optimized TiO2@Pt exhibits mass activity of 0.107 mA/ μ gPt and specific activity of 0.070 mA/cm2, outperforming the commercial benchmark Pt/C. In addition, the unique structure of TiO2@Pt also possesses excellent stability during the accelerated durability test (ADT). The sample is able to retain 80% of its original mass activity after 50000 cycles. It is also interesting and important to study the structural evolution of TiO2@Pt, especially Pt NPs, after such long cycles. Through Cs-STEM we verify the sample TiO2@Pt after ADT still has thin platinum layer on titanium dioxide. It is suggested the low-coordination platinum atom is preferentially dissolved and then deposited on the side of the highly coordinated platinum atoms when TiO2@Pt undergoes electrochemical scanning. Nitrogen doped TiO2 (N-doped TiO2) has also been applied to prepare N-doped TiO2@Pt catalysts. The properties and the metal-support interaction N-doped TiO2@Pt catalysts have been explored. Similar coreshell structured nanocatalyst was prepared by the same photo-deposition method. From the electrochemical results, it found that N-doped TiO2@Pt has improved specific activity, but not mass activity.