Structure, Optical Properties, and Photocatalytic Activity towards H2Generation and CO2Reduction of GaN Nanowires via Vapor-Liquid-Solid Process

Hong Pang,Defa Wang,Shuxin Ouyang,Lequan Liu,Hua Xu,Yunxiang Li

doi:10.1155/2014/894396

Abstract

High quality single crystalline GaN nanowires with large aspect ratio (>100) are synthesized on n-type Si (111) substrate via Au-catalyzed vapor-liquid-solid process. Morphology, crystal structure, and optical property of the as-synthesized GaN nanowires are characterized by means of X-ray diffraction, scanning/transmission electron microscopy, UV-vis diffuse reflection spectroscopy, and room temperature photoluminescence. The results indicate that the as-prepared GaN nanowires with a large aspect ratio are well crystallized in the hexagonal wurtzite structure, and a slight blue shift appears in both the absorption edge and emission peak probably due to the quantization effect. Photocatalytic H2evolution over the as-prepared GaN nanowires is performed with the incorporation of Pt or Rh as the cocatalyst, exhibiting greatly enhanced capability compared to the GaN powder tested under the same conditions. Moreover, photocatalytic CO2reduction over the GaN nanowires is also successfully realized using Pt or Rh as the cocatalyst, depending on which the products show a strong selectivity inherently related to the reductive electrons transferred by cocatalyst.

Highlights

In view of the globally concerned energy shortage and environment pollution issues, photocatalysis using semiconductor and solar energy has been regarded as an ideal green chemistry technology [1,2,3]
While TiO2-based photocatalysts were most popularly studied in last four decades [4], a huge number of new semiconducting materials have been developed for photocatalytic applications
High quality single crystalline GaN nanowires are successfully synthesized through a vapor-liquid-solid process

Summary

Introduction

In view of the globally concerned energy shortage and environment pollution issues, photocatalysis using semiconductor and solar energy has been regarded as an ideal green chemistry technology [1,2,3]. While TiO2-based photocatalysts were most popularly studied in last four decades [4], a huge number of new semiconducting materials have been developed for photocatalytic applications. A direct III–V group semiconductor GaN has been attracting extensive attention due to the following facts [5,6,7,8]: the band structure of GaN can encompass several possible redox potentials; in addition, the high stability of GaN makes it work well under various harsh conditions. One-dimensional (1D) nanomaterials have been paid much attention in photocatalytic field owing to their advantageous properties compared to the particulate materials [9]. 1D nanostructures provide the possibility of guiding the charge carriers transport in restricted pathways by limiting the transport in the transverse direction.

Methods

Results

Conclusion