物理化学学报 >> 2020, Vol. 36 >> Issue (7): 1905023.doi: 10.3866/PKU.WHXB201905023

所属专题: 纳米复合材料

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纳米颗粒结合ZIF-67衍生的PtCo-NC催化剂用于醇类燃料电氧化

方波,冯立纲*()   

  • 收稿日期:2019-05-05 录用日期:2019-06-13 发布日期:2019-06-17
  • 通讯作者: 冯立纲 E-mail:ligang.feng@yzu.edu.cn
  • 基金资助:
    国家自然科学基金(21603041)

PtCo-NC Catalyst Derived from the Pyrolysis of Pt-Incorporated ZIF-67 for Alcohols Fuel Electrooxidation

Bo Fang,Ligang Feng*()   

  • Received:2019-05-05 Accepted:2019-06-13 Published:2019-06-17
  • Contact: Ligang Feng E-mail:ligang.feng@yzu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21603041)

摘要:

在本工作中,通过在氮气保护下热解Pt纳米颗粒结合的ZIF-67制备了由ZIF-67原位产生的氮掺杂碳负载PtCo合金纳米颗粒组成的PtCo-NC复合催化剂。通过X射线衍射,扫描电子显微镜,透射电子显微镜等物理表征手段研究了催化剂的结构和形貌,并测试了该催化剂对醇类燃料甲醇和乙醇氧化的电化学性能。与参比样Pt/C相比,PtCo-NC催化剂的电催化活性与稳定性均得到了极大的提高,其优异的催化性能可以归因于抗一氧化碳中毒能力的提升和原位形成的PtCo纳米颗粒和氮掺杂载体间的协同作用。

关键词: 醇类氧化反应, 直接醇类燃料电池, 电催化剂, 铂基催化剂, 氮掺杂碳

Abstract:

Alcohols fuel electro-oxidation is significant to the development of direct alcohols fuel cells, that are considered as a promising power source for portable electronic devices. Currently, the catalyst was restricted by the serious poisoning effect and high cost of noble metals. Developing low-cost Pt alloy with high performance and anti-CO poisoning ability was highly desired. In this work, PtCo-NC catalyst was synthesized by combining Pt nanoparticles with ZIF-67 after annealing in the tube furnace and the in situ generated N-doped carbon from ZIF-67 was functionalized to support the PtCo alloy nanoparticle. The structure and morphology were probed by X-ray diffraction, scanning electron microscope and transmission electron microscope, and the electrochemical performance was evaluated for alcohols of methanol and ethanol oxidation in the acid electrolyte. Compared with the reference sample of Pt/C, several times performance enhancement for alcohols fuel oxidation was found on PtCo-NC catalyst as well as the good catalytic stability. Specifically, the peak current density of PtCo-NC was 79.61 mA∙cm−2 for methanol oxidation, about 2.2 times higher than that of the Pt/C electrode (36.97 mA∙cm−2) and 2.5 times higher than that of the commercial Pt/C electrode (31.23 mA∙cm−2); it was 62.69 mA∙cm–2 for ethanol oxidation, about 1.65 times higher than that of Pt/C catalyst (37.99 mA∙cm−2) and commercial Pt/C electrode (37.77 mA∙cm−2). These catalytic performances were also much higher than some analogous catalysts developed for alcohols fuel oxidation. A much higher anti-CO poisoning ability was demonstrated by the CO stripping voltammetry experiment, in which the COad oxidation peak potential for PtCo-NC was 0.46 V, ca. 110 mV negative shift compared with Pt/C catalyst at 0.57 V. A strong electronic effect was indicated by the peak position shifting to the lower binding energy direction by 0.3 eV on PtCo-NC compared with Pt/C reference catalyst. According to the d-band center theory, the electron-enriched state of Pt will decrease the interaction strength of poisoning intermediates adsorbed on its surface; Moreover, according to the bifunctional catalytic mechanism, the presence of Co can form the adsorbed oxygen-containing species (OH) more easily than Pt at low potentials, and this oxygen-species were helpful in the oxidation of COad at neighboring Pt sites. The high catalytic performance for alcohols fuel oxidation could be due to the largely improved anti-CO poisoning ability and the synergistic effect between the in situ formed PtCo nanoparticles and the N-doped carbon support.

Key words: Alcohols oxidation reaction, Direct alcohol fuel cell, Electro catalyst, Pt-base catalyst, N-doped carbon

MSC2000: 

  • O646