College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Jiangsu 215123, China.
Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China.; Beijing Innovation Center for Engineering Science and Advanced Technology, College of Engineering, Peking University, Beijing 100871, China.; Key Laboratory of Theory and Technology of Advanced Batteries Materials, College of Engineering, Peking University, Beijing 100871, China.
Sci Adv. 2017 Feb 24;3(2):e1601705. doi: 10.1126/sciadv.1601705. eCollection 2017 Feb.
The common knowledge is that Pt and Pt alloy nanoparticles (NPs) less than 2 nm are not desirable for oxygen reduction reaction (ORR). However, whether the same trend is expected in Pt-based nanowires (NWs) and nanoplates remains questionable because there is no scalable approach to make such Pt nanostructures. We report a general approach for preparing subnanometer Pt alloy NWs with a diameter of only 4 to 5 atomic layer thickness, ranging from monometallic Pt NWs to bimetallic PtNi and PtCo NWs and to trimetallic PtNiCo NWs. In a sharp contrast to Pt alloy NPs, the subnanometer Pt alloy NWs demonstrate exceptional mass and specific activities of 4.20 A/mg and 5.11 mA/cm at 0.9 V versus reversible hydrogen electrode (RHE), respectively, 32.3 and 26.9 times higher than those of the commercial Pt/C. Density functional theory simulations reveal that the enhanced ORR activities are attributed to the catalytically active sites on high-density (111) facets in the subnanometer Pt alloy NWs. They are also very stable under the ORR condition with negligible activity decay over the course of 30,000 cycles. Our work presents a new approach to maximize Pt catalytic efficiency with atomic level utilization for efficient heterogeneous catalysis and beyond.
人们普遍认为，小于 2nm 的 Pt 和 Pt 合金纳米颗粒（NPs）不利于氧还原反应（ORR）。然而，对于基于 Pt 的纳米线（NWs）和纳米板是否存在同样的趋势仍存在疑问，因为目前还没有可扩展的方法来制备这种 Pt 纳米结构。我们报道了一种通用的方法，用于制备亚纳米级 Pt 合金 NWs，其直径仅为 4 到 5 个原子层厚度，从单金属 Pt NWs 到双金属 PtNi 和 PtCo NWs，再到三金属 PtNiCo NWs。与 Pt 合金 NPs 形成鲜明对比的是，亚纳米级 Pt 合金 NWs 在 0.9V 相对于可逆氢电极（RHE）时表现出异常的质量和比活性，分别为 4.20 A/mg 和 5.11 mA/cm，分别是商业 Pt/C 的 32.3 倍和 26.9 倍。密度泛函理论模拟表明，增强的 ORR 活性归因于亚纳米级 Pt 合金 NWs 中高密度（111）晶面上的催化活性位。在 ORR 条件下，它们也非常稳定，经过 30000 次循环后，活性衰减可忽略不计。我们的工作为最大限度地提高 Pt 催化效率提供了一种新方法，实现了原子级利用率的高效异相催化及更多应用。
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