Surface polarization matters: enhancing the hydrogen-evolution reaction by shrinking Pt shells in Pt-Pd-graphene stack structures

Song Bai; Chengming Wang; Mingsen Deng; Ming Gong; Yu Bai; Jun Jiang; Yujie Xiong

doi:10.1002/anie.201406468

Surface polarization matters: enhancing the hydrogen-evolution reaction by shrinking Pt shells in Pt-Pd-graphene stack structures

Angew Chem Int Ed Engl. 2014 Nov 3;53(45):12120-4. doi: 10.1002/anie.201406468. Epub 2014 Aug 26.

Authors

Song Bai¹, Chengming Wang, Mingsen Deng, Ming Gong, Yu Bai, Jun Jiang, Yujie Xiong

Affiliation

¹ Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials, School of Chemistry and Materials Science, and Laboratory of Engineering and Material Science, University of Science and Technology of China, Hefei, Anhui 230026 (P. R. China) http://staff.ustc.edu.cn/∼yjxiong/

PMID: 25155584
DOI: 10.1002/anie.201406468

Abstract

Surface charge state plays an important role in tuning the catalytic performance of nanocrystals in various reactions. Herein, we report a synthetic approach to unique Pt-Pd-graphene stack structures with controllable Pt shell thickness. These unique hybrid structures allow us to correlate the Pt thickness with performance in the hydrogen-evolution reaction (HER). The HER activity increases with a decrease in the Pt thickness, which is well explained by surface polarization mechanism as suggested by first-principles simulations. In this hybrid system, the difference in work functions of Pt and Pd results in surface polarization on the Pt surface, tuning its charge state for hydrogen reduction. Meanwhile, the supporting graphene provides two-dimensional channels for efficient charge transport, improving the HER activities. This work opens up possibilities of reducing Pt usage while achieving high HER performance.

Keywords: hybrid structures; hydrogen-evolution reaction; nanocrystals; surface polarization; work function.