Oxygen reduction and ethanol oxidation reaction (ORR and EOR) have been studied on graphene nanosheet-supported (GNS) pure Pd and Pd3Y nanoscale-alloy (Pd/GNS and Pd3Y/GNS) electrocatalysts. The electrochemical studies were carried out for ORR both in acidic and alkaline solutions employing a rotating disk electrode (RDE), and performed for EOR in alkaline media with cyclic voltammetry method. The structure and composition of the Pd and Pd3Y nanoparticles were verified using TEM, XRD and XPS. We combine the experimental measurements with ab initio density functional theory (DFT) calculations to identify the d-band center position of Pd atom in the pure Pd and Pd3Y alloys as a function of site on near the surface. Both approaches clearly show that alloying the Pd with Y significantly modifies the electronic structures of Pd atoms. Core-level of Pd 3d5/2 shifts to a negative value, which increases the d-band center of Pd atom and enhances the bond strength of PdO, which implies good catalysts for EOR but ORR. Our results indicate that the electronic structure of the Y-modified bimetallic Pd alloy is a good descriptor for the catalytic activity.
Bibliographical noteFunding Information:
This work was supported by the New & Renewable Energy R&D program (no. 20103020030020 and 20113020030020 ) under the Korea Government Ministry of Knowledge Economy , and funded by National Research Foundation of Korea (no. 20120005212 ) and the Global Frontier R&D Program on Center for Multiscale Energy System ( 0420-20110157 ) by Korea Government. It was also supported by DGIST R&D Program of the Ministry of Education, Science and Technology of Korea ( 12-BD-0405 ) and by the KISTI with supercomputing resources including technical support (KSC-2012-C2-15).
All Science Journal Classification (ASJC) codes
- Environmental Science(all)
- Process Chemistry and Technology