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

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

doi:10.3390/molecules26102904

Akira Nishimura, Ryouga Shimada + Show 3 more

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https://doi.org/10.3390/molecules26102904

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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.

Highlights

Because of large concerns around the world, the global warming problem is a hot area of R&D
It was found that nanosized Cu and Pd particles were loaded on TiO2 film uniformly
This study has confirmed 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

Summary

Introduction

Because of large concerns around the world, the global warming problem is a hot area of R&D. Each country has set a goal to reduce the amount of CO2 emissions. In. Japan, the prime minister has declared the intent to reduce the effective CO2 emissions to zero by 2050. The global mean concentration of CO2 in atmosphere had increased up to 410 ppmV in September 2019, which was 25 ppmV increase from the value in 2009 [1]. Development of technologies which can reduce the amount of CO2 in the atmosphere the is urgently required. Solar conversion of CO2 to fuel seems a promising procedure to solve the global warming problem for sustainable development of society. One pathway to realize solar conversion of CO2 is photochemical reactions

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