Influence of lanthanum on morphology and electrochemical performance of nano‐platinum‐based catalytic membrane electrode

Abstract

The current research of platinum (Pt)–based catalysts focuses on reducing Pt loading in the catalysts while enhancing the catalytic activity. As a rare‐earth element, lanthanum (La) has demonstrated good synergistic effect with Pt‐based catalysts, because of its catalytic promoting capability and high dispersibility. Here, we fabricated La‐doped nano‐Pt‐based catalytic membrane electrode using ion beam sputtering method. The effect of La on the morphology and electrochemical performance of the catalytic membrane electrode was investigated by scanning electron microscope, X‐ray photoelectron spectroscopy, and electrochemical measurements. Compared with pure Pt‐based sample, the electrochemical activity specific area of the La‐doped sample increases by 74.59%, with 63.95% increase in exchange current density. The results also show that La2O3 enhances oxygen enrichment of the membrane electrode and reduces interfacial energy among Pt grains while pinning the grain boundaries. In addition, the inductively coupled plasma atomic emission spectroscopy (ICP‐AES) measurement shows that the Pt loading in the membrane electrodes is below 0.1 mg/cm2. Thus, enhanced catalytic performance is achieved in catalysts with lower Pt loading.