Comparison of CO2 Reduction Performance with NH3 and H2O between Cu/TiO2 and Pd/TiO2

Akira Nishimura; Ryouga Shimada; Yoshito Sakakibara; Akira Koshio; Eric Hu

doi:10.3390/molecules26102904

Comparison of CO₂ Reduction Performance with NH₃ and H₂O between Cu/TiO₂ and Pd/TiO₂

Molecules. 2021 May 13;26(10):2904. doi: 10.3390/molecules26102904.

Authors

Akira Nishimura¹, Ryouga Shimada¹, Yoshito Sakakibara¹, Akira Koshio², Eric Hu³

Affiliations

¹ Division of Mechanical Engineering, Graduate School of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507, Japan.
² Division of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507, Japan.
³ School of Mechanical Engineering, the University of Adelaide, Adelaide, SA 5005, Australia.

Abstract

The aim of this study is to clarify the effect of doped metal type on CO₂ reduction characteristics of TiO₂ with NH₃ and H₂O. Cu and Pd have been selected as dopants for TiO₂. In addition, the impact of molar ratio of CO₂ to reductants NH₃ and H₂O has been investigated. A TiO₂ photocatalyst was prepared by a sol-gel and dip-coating process, and then doped with Cu or Pd fine particles by using the pulse arc plasma gun method. The prepared Cu/TiO₂ film and Pd/TiO₂ film were characterized by SEM, EPMA, TEM, STEM, EDX, EDS and EELS. This study also has investigated the performance of CO₂ reduction under the illumination condition of Xe lamp with or without ultraviolet (UV) light. As a result, it is revealed that the CO₂ reduction performance with Cu/TiO₂ under the illumination condition of Xe lamp with UV light is the highest when the molar ratio of CO₂/NH₃/H₂O = 1:1:1 while that without UV light is the highest when the molar ratio of CO₂/NH₃/H₂O = 1:0.5:0.5. It is revealed that the CO₂ reduction performance of Pd/TiO₂ is the highest for the molar ratio of CO₂/NH₃/H₂O = 1:1:1 no matter the used Xe lamp was with or without UV light. The molar quantity of CO per unit weight of photocatalyst for Cu/TiO₂ produced under the illumination condition of Xe lamp with UV light was 10.2 μmol/g, while that for Pd/TiO₂ was 5.5 μmol/g. Meanwhile, the molar quantity of CO per unit weight of photocatalyst for Cu/TiO₂ produced under the illumination condition of Xe lamp without UV light was 2.5 μmol/g, while that for Pd/TiO₂ was 3.5 μmol/g. This study has concluded that Cu/TiO₂ is superior to Pd/TiO₂ from the viewpoint of the molar quantity of CO per unit weight of photocatalyst as well as the quantum efficiency.

Keywords: CO2 reduction; Cu/TiO2 photocatalyst; Pd/TiO2 photocatalyst; molar ratio of reductants.