Improved durability and activity of Pt/C catalysts through atomic layer deposition of tungsten nitride and subsequent thermal treatment
Improved durability and activity of Pt/C catalysts through atomic layer deposition of tungsten nitride and subsequent thermal treatment
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DOI：
10.1016/j.apcatb.2019.05.036
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
W. McNeary;S. Zaccarine;Annika Lai;Audrey E. Linico;S. Pylypenko;A. Weimer
中科院分区：
文献类型：
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作者：
W. McNeary;S. Zaccarine;Annika Lai;Audrey E. Linico;S. Pylypenko;A. Weimer
氮化钨（WN）的原子层沉积（ALD）通过向表面添加保护性WN纳米结构来增强碳支撑的Pt纳米颗粒氧还原反应（ORR）催化剂的耐久性和活性。在ALD改性的催化剂上进行低温氧化然后高温还原的合成后热处理序列。考察了ALD工艺和热处理对催化剂结构和电化学性能的影响。通过ICP-MS、STEM和EDS绘图以及X射线衍射的表征表明，ALD工艺在整个表面上均匀地沉积WN。热处理导致表面上的氮化物的量减少，并产生单独的Pt和W域。通过旋转圆盘电极伏安法测定了催化剂的电化学性能。观察到经热处理的ALD催化剂对ORR具有高质量活性（465 mA/mg），超过基准Pt/C（277 mA/mg），并且在加速耐久性测试后表现出电化学性质的上级保持。在耐久性测试之前和之后的粒度分布的分析还表明，与未涂覆的材料相比，Pt纳米颗粒的机械稳定性在热处理的ALD催化剂中增强。
Atomic layer deposition (ALD) of tungsten nitride (WN) enhanced the durability and activity of a carbon-supported Pt nanoparticle oxygen reduction reaction (ORR) catalyst by adding protective WN nanostructures to the surface. A post-synthesis thermal treatment sequence of low-temperature oxidation followed by high-temperature reduction was carried out on the ALD-modified catalyst. The effects of the ALD process and thermal treatment on the structure and electrochemical properties of the catalyst were examined. Characterization through ICP-MS, STEM and EDS mapping, and X-ray diffraction showed that the ALD process deposited WN homogenously across the surface. Thermal treatment resulted in a reduced amount of nitride on the surface and produced separate Pt and W domains. The electrochemical performance of the catalysts is measured through rotating disk electrode voltammetry. The thermally-treated ALD catalyst was observed to have a high mass activity towards the ORR (465 mA/mg), surpassing benchmark Pt/C (277 mA/mg), and demonstrated superior retention of electrochemical properties after an accelerated durability test. Analysis of particle size distributions before and after durability testing also indicated that the mechanical stability of the Pt nanoparticles is enhanced in the thermally-treated ALD catalyst compared to the uncoated materials.