以次磷酸钠为还原剂,采用浸渍法制备直接甲醇燃料电池用60%PtRuP/C(Pt与Ru的摩尔比为1:1)催化剂,并考察浸渍液pH值和P元素对催化剂活性的影响。采用X射线衍射、透射电镜、X射线能量分散谱和X射线光电子能谱等对催化剂进行结构、组成及形貌进行表征,通过线性扫描伏安法和计时电流曲线考察催化剂对甲醇氧化的电化学性能。研究结果表明:pH值对催化剂的结构和活性有很大影响,pH值为7时制备的催化剂分散均匀,平均粒径为2.8nm,并且具有最高的对甲醇催化活性和抗毒化性能;与不含P的PtRu/C催化剂相比,PtRuP/C催化剂具有更高的催化活性,扫速为20mV/s、电位为0.45V时氧化甲醇的电流密度达到63mA/cm^2。
A 60% PtRuP/C anode electrocatalyst for a direct methanol fuel cell(DMFC) was prepared by impregnation method using sodium hypophosphite as reductive agent. Effects of pH values and element P on the catalyst activities were studied. The structure, component and morphology were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS) and X-ray photoelectron spectra(XPS). The electrocatalytic performances were examined by linear sweep voltammetry (LSV) and chronoamperometry. The results show that the structure and electrocatalytic properties are greatly influenced by the pH value of impregnating solution. The catalyst prepared at the pH value of 7 has high dispersion, the highest catalytic activity for methanol oxidation, good tolerance to poisoning species and the average particle size of 2.8 nm. Compared with the PtRu/C catalyst, the PtRuP/C catalyst possesses a higher catalytic activity producing current density of 63 mA/cm^2 at 0.45 V (vs. SCE) with a scanning rate of 20 mV/s.