Tuning saw-toothed morphology on Pd/Pt nanocubes as oxygen reduction catalysts by co-surfactant synthesis method

摘要

Herein, a facile co-surfactant method has been reported for the synthesis of core-shell Pd/Pt saw-toothed nanocubes (Pd/Pt STNCs). In this method, saw-toothed morphologies increase with decreasing ratio (R) of the concentration of cetyltrimethylammonium bromide to cetyltrimethylammonium chloride in the synthesis solution. High-resolution transmission electron microscopy (HR-TEM) images reveal that the Pd/Pt STNC prepared using R = 4 (Pd/Pt STNCR = 4) has (3 1 0) and (4 1 0) facets on its edge, whereas the Pd/Pt STNCs prepared using R = 1 (Pd/Pt STNCR (= 1)) and 0.25 (Pd/Pt STNCR = 0.25) have (3 1 1) high-index facets. Furthermore, the comparison based on electrochemical surface area (ESA) shows that carbon-supported Pd/Pt STNCR = 4 used for catalysing acidic oxygen reduction exhibits a kinetic current of 0.44 mA at 0.9 V (vs. RHE), which is 1.4-times greater than that obtained for commercial Pt/C (0.31 mA). The higher activity could be caused by enriched electrons on the Pt outershell with less adsorbed Cl- ions, as confirmed by the X-ray photoelectron analyses. Accelerated durability test results show that the Pd/Pt STNCR = 4 catalyst is more stable than Pt/C.