Photocatalytic Reduction of CO2 by ZnO Micro/nanomaterials with Different Morphologies and Ratios of {0001} Facets.

Xiaodi Liu,Liqun Ye,Xiaoxu Ji,Shanshan Liu,Yinping Li

doi:10.1038/srep38474

Abstract

ZnO microspheres, ZnO microflowers and ZnO nanorods are successfully synthesized via a convenient solvothermal method in distilled water-ethanol mixed medium. The as-prepared ZnO micro/nanomaterials are characterized by XRD, SEM, TEM, HRTEM, XPS, BET, and UV-Vis. The morphologies and exposed facets of the ZnO micro/nanomaterials can be controlled by simply changing the volume ratio of distilled water to ethanol, and their formation mechanisms are also proposed. In addition, the photocatalytic activities of the ZnO samples are investigated towards the photoreduction of CO2 to CO. It is found that ZnO nanorods with high ratio of {0001} facets and large surface areas possess higher CO formation rate (3.814 μmol g−1 h−1) in comparison with ZnO microspheres and ZnO microflowers (3.357 and 1.627 μmol g−1 h−1, respectively). The results can not only provide an important indication about the influence of the {0001} facets on the activity of CO2 photoreduction over ZnO, but also demonstrate a strategy for tuning the CO2 photoreduction performance by tailoring the surface structures of ZnO micro/nanomaterials.

Highlights

The ever-increasing emission of CO2 in the atmosphere and the diminishing of fossil resources have driven researchers to control the atmospheric level of CO2 and explore renewable energy sources[1]
We report the controlled synthesis of ZnO microsphere (S-1), ZnO microflowers (S-2), and ZnO nanorods (S-3) with different ratios of {0001} facets by a facile and efficient solvothermal method
The morphologies and crystalline natures of the products are characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and high-resolution TEM (HRTEM)

Summary

Introduction

The ever-increasing emission of CO2 in the atmosphere and the diminishing of fossil resources have driven researchers to control the atmospheric level of CO2 and explore renewable energy sources[1]. The photocatalytic reaction usually occurs at the interface between the reactant (i.e., CO2) and the photocatalyst; the photocatalytic activity of the catalyst depends on the morphology and is strictly related to the surface atomic and electronic structures[4,5]. What is more, it is well-known that different crystal facets of a semiconductor have different atomic arrangements and electronic structures, endowing them with distinctive photocatalytic activities[6]. S-3 exhibits the best activity for CO2 photoreduction under sunlight irradiation

Methods

Results

Conclusion