聚苯胺共价接枝碳纳米管负载Pt催化剂的制备及对甲醇电催化性能的研究

Preparation of Polyaniline Covalently Grafted Carbon Nanotubes Supported Pt Catalysts and Its Electrocatalytic Performance for Methanol

以氨基化的碳纳米管为基体,通过界面聚合方法将聚苯胺共价接枝于碳纳米管表面,负载催化剂颗粒Pt.通过透射电镜(TEM)、X射线衍射(XRD)及电化学方法对催化剂进行了表征.TEM结果表明通过界面聚合的方法可以使聚苯胺均匀地接枝于碳纳米管表面.电化学测试结果表明,碳纳米管共价接枝聚苯胺作为载体可以提高催化剂的抗CO中毒性能,有利于对甲醇的催化氧化.研究其对甲醇的催化活性,并与商业的JM(Pt/C)催化剂进行了对比.结果表明,碳纳米管共价接枝聚苯胺,有效提高了催化剂的稳定性,延长催化剂的寿命.

Recently, covalently functionalization carbon nanotubes have been received special attention because of the ex- pansive application prospect in the areas of nanoscience and nanotechnology. Moreover, covalent functionalization of carbon nanotubes can readily deal with fundamental issues of purification, solubilization, and processing. In particular, polyaniline, due to its high electronic conductivity, good environmental stability, easy preparation and reversible acid-base dop- ing-dedoping chemistry, has been one of the most studied conducting polymers. Recently, CNTs-PANI composites were in- vestigated widely, such as supercapacitor, optoelectronic devices, sensing and catalysis as well. In this work, uniform struc- tures PANI covalently grafted onto CNTs functionalization with -NH2 groups composites have been obtained by using liq- uid/liquid（L/L） interfacial polymerization method. The interfacial system was established by using CNTs, FeC13, HC1 as top aqueous phase and aniline, CH2C12 as bottom organic phase, which effective suppress second growth of PANI and obtain uniform CNTs-NH-PANI composites. Concerning CNTs-NH-PANI composites, PANI can covalently be grafted on CNTs with -NH2 groups. The resulted CNTs-NH-PANI composites have abundant -NH2 groups on their surface, serving as anchor centers for achieving high Pt dispersion. More important, PANI uniformly grafted on CNTs is prone to disperse the bundle of CNTs into separated lines and improve water dispersibility of obtained CNTs-NH-PANI composites. Subsequently, PtNPs were successfully deposited on the CNTs-PANI to form ternary hybrids. Potential application of the ternary hybrids as high performance catalysts for direct methanol fuel cells has been explored. The catalyst samples were characterized by transmis- sion electron microscopy （TEM）, X-ray diffraction （XRD） and electrochemical methods. TEM results showed that the hier- archical CNTs-PANI composites with uniform morphology have been successfully prepared due to hydrophilic -OH and -NH2 groups covalently functionalized onto the surface of CNTs. Moreover, the electrochemical measurement show that the Pt/CNTs-NH-PANI hybrid have better stabilities compared with commercial JM （Pt/C） catalyst. The long-term durability test of the Pt/CNTs-CO-PANI, Pt/CNTs-NH-PANI and Pt/C catalysts shows that PANI grafted on CNTs as catalyst supports have better stabilities and more tolerant toward poisoning. Moreover, PANI covalently grafted on CNTs as catalyst supports has more excellent performance. The lt^1~, of Pt/CNTs-NH-PANI catalyst for electrocatalytic methanol oxidation is 1.65 which is nearly 1.6 and 1.2 times than that of the commercial JM（Pt/C） and Pt/CNTs-CO-PANI catalysts, respectively. The results show that carbon nanotubes covalenfly grafting polyaniline as support can effectively improve the catalyst stability, increas- ing the service life of the catalyst.