Su Bing-Jian, Wang Kuan-Wen, Tseng Chung-Jen, Pao Chih-Wen, Chen Jeng-Lung, Lu Kueih-Tzu, Chen Jin-Ming
National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan, ROC.
Institute of Materials Science and Engineering, National Central University, Taoyuan City 32001, Taiwan, ROC.
ACS Appl Mater Interfaces. 2020 Jun 3;12(22):24710-24716. doi: 10.1021/acsami.0c02415. Epub 2020 May 19.
To prevent the corrosion of carbon and to enhance corrosion resistance, charge transfer, and mass transfer, graphene, which exhibits a high surface area and good conductivity, was used as an electrocatalyst support for a fuel cell. PtSn/G electrocatalysts for the oxygen reduction reaction (ORR) were prepared with alcohol reduction. The characterization of synthesized catalysts was analyzed according to the energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and extended X-ray absorption fine structure (EXAFS). The electrochemical performance was analyzed with cyclic-voltammetry (CV), linear sweep voltammetry (LSV), and accelerated degradation test (ADT) measurements. The PtSn/G electrocatalysts showed more positive onset potential and larger ORR mass activity than commercial Pt/C catalysts after 5000 cycles of ADT, indicating that in an acidic environment, PtSn/G is more chemically stable than Pt/C. Graphene has effective acid tolerance, is more stable against corrosion, and shows increased stability through preventing PtSn nanoparticles from detaching from the surface. According to the in situ quick EXAFS (QEXAFS) under a CV test to clarify the potential-dependent state of the PtSn/G electrocatalyst, the results show that the electrode surface is reproducible; there is no perceptible change in the oxidation state of the PtSn/G electrocatalyst. The radial distribution function (RDF) of the EXAFS spectra shows that the adsorption and desorption of H and OH cause no structural change in the PtSn crystallites. This work provides insight into the reaction mechanism of proton electroreduction and hydrogen adsorption on a PtSn/G electrocatalyst surface.
为防止碳的腐蚀并提高耐腐蚀性、电荷转移和传质，具有高表面积和良好导电性的石墨烯被用作燃料电池的电催化剂载体。采用醇还原法制备了用于氧还原反应（ORR）的PtSn/G电催化剂。根据能量色散光谱仪（EDS）、X射线衍射（XRD）、高分辨率透射电子显微镜（HRTEM）和扩展X射线吸收精细结构（EXAFS）对合成催化剂进行了表征分析。通过循环伏安法（CV）、线性扫描伏安法（LSV）和加速降解试验（ADT）测量对电化学性能进行了分析。经过5000次ADT循环后，PtSn/G电催化剂比商业Pt/C催化剂表现出更正的起始电位和更大的ORR质量活性，表明在酸性环境中，PtSn/G比Pt/C在化学上更稳定。石墨烯具有有效的耐酸性，对腐蚀更稳定，并且通过防止PtSn纳米颗粒从表面脱离而表现出更高的稳定性。根据CV测试下的原位快速EXAFS（QEXAFS）以阐明PtSn/G电催化剂的电位依赖状态，结果表明电极表面具有可重复性；PtSn/G电催化剂的氧化态没有明显变化。EXAFS光谱的径向分布函数（RDF）表明，H和OH的吸附和解吸不会导致PtSn微晶的结构变化。这项工作为质子电还原和氢在PtSn/G电催化剂表面吸附的反应机理提供了见解。
