Applied Catalysis B: Environmental, Vol.241, 424-429, 2019
Surface reconstruction engineering of twinned Pd2CoAg nanocrystals by atomic vacancy inducement for hydrogen evolution and oxygen reduction reactions
The integration of different active sites into metallic catalysts, which may impart new properties and functionalities, is desirable yet challenging. Herein, a novel strategy is demonstrated to integrate atomic vacancies onto a twinned Pd2CoAg surface. This strategy shows that such integration is highly efficient for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) catalysis at room temperature. We characterize the composition and structure of the twinned Pd2CoAg nanocrystals with vacancy (v-Pd2CoAg NCs) interfaces and it is shown that the Co addition not only increases the atomic vacancies of Pd2Ag twinned interface, but also leads to the formation of oxygen vacancies on the surface of CoOx. The synergistic effect of the surface atomic vacancies and metal twinned interfaces of v-Pd2CoAg NCs can tune the charge-density distribution on the surface of the electrocatalysts, and result in a 5 times increase in ORR mass activity than that of Pt/C at 0.9 V. This study provides a foundation for the rational design of 'active sites' for practical HER and ORR electrocatalysts.