Photocatalytic CO2 reduction and hydrogen production over Pt/Zn-embedded β-Ga2O3 nanorods

Abstract

Gallium oxide has shown a potential catalyst application in energy and environment. Herein, β-Ga2O3 and Zn-embedded β-Ga2O3 nanorods were prepared by hydrothermal method and post-thermal annealing process. The physicochemical properties were examined by scanning electron microscopy, electron transmission microscopy (TEM), Auger elemental mapping, X-ray diffraction crystallography, UV–visible absorption, Raman, Fourier-transform infrared, and X-ray photoelectron spectroscopy. Photocatalytic CO2 reduction products over β-Ga2O3 nanorods in gaseous CO2/H2O atmosphere were found to be CO, CH4, and H2 with rates of 0.055, 0.058, and 14.8 μmol⋅g−1⋅h−1, respectively under UVC irradiation confirmed by gas chromatography. Upon 5 mol% Zn-embedding, the rates of CO, CH4, and H2 were observed to be 1.49, 0.24, and 0.19 μmol⋅g−1⋅h−1, respectively. The CO and CH4 yields were increased by 27 × and 4×, respectively. CH3OH was barely detected for Zn or Pt-only embedded β-Ga2O3, but significantly increased to 0.19 μmol⋅g−1⋅h−1 upon Pt/Zn(5 mol%)-cocatalyst embedding. The photocatalytic hydrogen production was increased by 3.6 × and 27.4 × upon Pt/Zn-cocatalyst embedding, compared with those of Zn-embedded and bare β-Ga2O3, respectively. The Pt/Zn-cocatalyst embedding was found to show 2.5 × higher rate than the Pt-only embedding. The rate reached to 404.5 μmol⋅g−1⋅h−1 for Pt(0.5 nm)/Zn(2 mol%)/β-Ga2O3. The unique demonstration tests provide precious information for the improvement of Ga2O3-based CO2 reduction and hydrogen production catalysts.