高耐甲醇性和稳定性的纳米复合阴极催化剂

报导了一种由酞菁氧钛、铂金属纳米簇和氮杂化碳纳米角结构基元组装而成的新型纳米复合电化学催化剂(TiOPc-Pt/NSWCNH)的制备、表征及电催化性能. 在TiOPc-Pt/NSWCNH催化剂中, 氮杂化碳纳米角堆积形成多孔导电网络, 铂纳粒子均匀地分散于上述多孔导电网络中, 部分铂纳粒子与TiOPc微晶直接接触. 在甲醇存在的条件下, TiOPc-Pt/NSWCNH对氧还原反应表现出高催化活性和优良的选择性与稳定性. 在甲醇浓度为0.5 mol·L^-1的高氯酸水溶液中, TiOPc-Pt/NSWCNH催化氧还原反应的起始电位比商购Pt/C-JM催化剂提高了260 mV, 其质量活性和比活性(0.85 V (参比电极为可逆氢电极(RHE)))分别为83.5 A·g^-1和0.294 mA·cm^-2, 远高于Pt/C-JM催化剂. 在含氧气氛下, 于甲醇高氯酸水溶液中, 对TiOPc-Pt/NSWCNH和TiOPc-Pt/C催化剂进行了循环伏安法加速老化实验研究(0.6-1.0 V, 15000个循环), 结果表明TiOPc-Pt/NSWCNH具有更高的稳定性. TiOPc-Pt/NCNH催化剂的高耐醇性可能得益于由TiOPc微晶向Pt纳米粒子的电子转移, 其高稳定性主要得益于氮杂化碳纳米角的高石墨化程度及纳米角堆积而成网络结构.

Nanocomposite Cathode Catalyst with High Methanol Tolerance and Durability

We report the preparation, characterization and elelctrocatalytic properties of a novel nanocomposite cathode catalyst (TiOPc-Pt/NSWCNH) which is assembled using Pt nanoclusters, TiOPc nanocrystal, and nitrogen-doped single walled carbon nanohorns (NSWCNHs) as building blocks. TiOPc-Pt/NSWCNH is characterized by inserting most of the Pt nanoparticles in nano-networks formed by stacking of NSWCNHs, and contacting of a part of the Pt nanoparticles with TiOPc nanocrystals. TiOPc-Pt/NSWCNH exhibits high electrocatalytic activity, excellent selectivity and durability for oxygen reduction reaction (ORR) in the presence of methanol. In an O₂-saturated HClO₄ aqueous solution containing methanol (0.5 mol·L^-1), the onset potential over the TiOPc-Pt/NSWCNH catalyst shifted by more than 260 mV toward positive relative to that over a commercial Pt/C-JM catalyst. The mass activity and specific activity for ORR over TiOPc-Pt/NSWCNH at 0.85 V (versus a reversible hydrogen electrode (RHE)) was 83.5 A·g^-1 and 0.294 mA·cm^-2, respectively, which were much higher than those of Pt/C-JM. Cyclic voltammetry accelerated aging tests (0.6-1.0 V for 15000 cycles) in an O₂-saturated HClO₄ aqueous solution containing methanol revealed that TiOPc-Pt/NSWCNH possessed a higher durability compared to TiOPc-Pt/C. The high methanol tolerance of TiOPc-Pt/NCNH may be mainly derived from the electron transfer from TiOPc nanocrystals to Pt nanoparticles. The nano-network and the high graphitization degree of NSWCNHs are responsible for the excellent durability of TiOPc-Pt/NSWCNH.