Promoted stability and electrocatalytic activity of PtRu electrocatalyst derived from coating by cerium oxide with high oxygen storage capacity

Abstract

Platinum-ruthenium (PtRu) electrocatalyst is traditionally used in the direct methanol fuel cells (DMFCs) as anodic electrocatalyst since Ru promotes the CO anti-poisoning of the neighbored Pt; however, Ru is dissolvable in acid media resulting in low stability of PtRu electrocatalyst. Here, we report a facile method to decelerate the Ru dissolution and to enhance the CO anti-poisoning by coating PtRu nanoparticles with cerium oxide (CeO2). C/PtRu@CeO2 exhibits only 30% loss in electrochemical surface area (ECSA) after 4200 potential cycles; in contrast, ECSA loss reaches 55% for the bare PtRu electrocatalyst. Meanwhile, the methanol oxidation reaction (MOR) activity is 2.8 fold higher by comparison with bare electrocatalyst. The enhanced MOR activity is attributed to the high oxygen storage capacity of CeO2 promoting the complete methanol oxidation. And the CO stripping voltammetry result shows that the CO oxidation peaks of C/PtRu@CeO2 negatively shift by 60 mV and 250 mV before and after stability test compared to those of C/PtRu electrocatalyst, respectively, suggesting an enhanced CO anti-positioning for C/PtRu@CeO2. Moreover, the fuel cell performance of C/PtRu@CeO2 reaches 49 mW cm−2; while, power density of C/PtRu is 45 mW cm−2 at 80 °C.