Photocatalytic activity of silicon-based nanoflakes for the decomposition of nitrogen monoxide.

Hiroshi Itahara,Xiaoyong Wu,Kazunobu Kojima,Tsugio Sato,Shu Yin,Haruo Imagawa,Shigefusa F Chichibu

doi:10.1039/c7dt01682d

Hiroshi Itahara, Xiaoyong Wu + Show 5 more

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https://doi.org/10.1039/c7dt01682d

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Abstract

The photocatalytic decomposition of nitrogen monoxide (NO) was achieved for the first time using Si-based nanomaterials. Nanocomposite powders composed of Si nanoflakes and metallic particles (Ni and Ni3Si) were synthesized using a simple one-pot reaction of layered CaSi2 and NiCl2. The synthesized nanocomposites have a wide optical absorption band from the visible to the ultraviolet. Under the assumption of a direct transition, the photoabsorption behavior is well described and an absorption edge of ca. 1.8 eV is indicated. Conventional Si and SiO powders with indirect absorption edges of 1.1 and 1.4 eV, respectively, exhibit considerably low photocatalytic activities for NO decomposition. In contrast, the synthesized nanocomposites exhibited photocatalytic activities under irradiation with light at wavelengths >290 nm (<4.28 eV). The photocatalytic activities of the nanocomposites were confirmed to be constant and did not degrade with the light irradiation time.

Highlights

The discovery of strong visible luminescence emitted from porous silicon (Si)[1] has stimulated research into the synthesis of Si nanomaterials for optoelectronic applications
A larger amount of Si crystallized with the diamond c-Si structure and formed Ni3Si by reaction with Ni, but excess Si still remained as amorphous Si nanoflakes
No crystalline phases could be assigned for the commercial SiO powder (Fig. 1(g)); SiO was reported to be a mixture of nanosized elemental Si and amorphous SiO2.25

Summary

Introduction

The discovery of strong visible luminescence emitted from porous silicon (Si)[1] has stimulated research into the synthesis of Si nanomaterials for optoelectronic applications. Nanocomposite powders composed of Si nanoflakes and metallic particles (Ni and Ni3Si) were synthesized using a simple one-pot reaction of layered CaSi2 and NiCl2. The synthesized nanocomposites exhibited photocatalytic activities under irradiation with light at wavelengths >290 nm (

Results

Conclusion