title: Surface polarization matters: enhancing the hydrogen-evolution reaction by shrinking Pt shells in Pt-Pd-graphene stack structures.
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.
authors.affiliation: 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/
authors.forename: Song
authors.initials: S
authors.lastname: Bai
authors.forename: Chengming
authors.initials: C
authors.lastname: Wang
authors.forename: Mingsen
authors.initials: M
authors.lastname: Deng
authors.forename: Ming
authors.initials: M
authors.lastname: Gong
authors.forename: Yu
authors.initials: Y
authors.lastname: Bai
authors.forename: Jun
authors.initials: J
authors.lastname: Jiang
authors.forename: Yujie
authors.initials: Y
authors.lastname: Xiong
keywords: hybrid structures; hydrogen-evolution reaction; nanocrystals; surface polarization; work function