Heterointegration of Pt/Si/Ag Nanowire Photodiodes and Their Photocatalytic Properties

• Published in: Advanced functional materials 2010-09, Vol.20 (18), p.n/a
• Main Authors: Qu, Yongquan, Xue, Teng, Zhong, Xing, Lin, Yung-Chen, Liao, Lei, Choi, Jina, Duan, Xiangfeng
• Format: Article
• Language: English
• Subjects: heterostructures; nanowires; photocatalysis; photodiodes
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201090081

Photocatalyst mediated photoelectrochemical processes can make use of the photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. Here, it is shown that a Pt/Si/Ag nanowire heterostructure can be rationally synthesized to integrate a nanoscale metal‐semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. The synthesis of Pt/Si/Ag nanowire diodes involves a scalable process including the formation of silicon nanowire array through wet chemical etching, electrodeposition of platinum and photoreduction of silver. The Pt/Si/Ag diodes exhibit highly efficient photocatalytic activity for a wide range of applications including environmental remediation and solar fuel production in the visible range. In this article, photodegradation of indigo carmine and 4‐nitrophenol are used to evaluate the photoactivity of Pt/Si/Ag diodes. The Pt/Si/Ag diodes also show high activity for photoconversion of formic acid into carbon dioxide and hydrogen. A Pt/Si/Ag heterostructure nanowire is created to integrate a metal‐semiconductor Schottky diode with two separate metal catalysts to form a standalone photoelectric nanodevice for photocatalytic applications. Under light irradiation, the electron‐hole pairs can be generated and quickly separated by the built‐in potential and transport in two opposite directions towards the respective catalysts for redox reactions, enabling Pt/n‐Si/Ag heterojunction nanowire photodiodes to function as highly efficient photocatalysts.