Enhanced Photoreduction Activity of Carbon Dioxide over Co₃O₄/CeO₂Catalysts under Visible Light Irradiation

Abstract

A series of new two semiconductor catalysts, Co3O4/CeO2, were prepared by glycine-nitrate combustion method for photocatalytic reduction of carbon dioxide to produce methanol and ethanol under visible light (λ>400 nm) irradiation. The catalysts were characterized by BET, UV-vis spectra, XRD, SEM, PL, and XPS and the results indicated that the catalyst with 5 wt.% of Co3O4has the highest yield among all kinds of tests with the methanol yield of 1.52 μmol·g−1·h−1and the ethanol yield of 4.75 μmol·g−1·h−1, which are about 2.34 and 1.71 times as large as those of CeO2. However, methanol and ethanol can hardly be detected for Co3O4under the same condition because of its too narrow band gap. The improvement of the photoreduction activity of Co3O4doped CeO2was caused by the separation of electron-hole pairs of Co3O4/CeO2and charge transfer between Co3O4and CeO2, mimicking the Z-scheme in photosynthesis.

Spectroscopic and structural properties of CeO2 nanocrystals doped with La3+, Nd3+ and modified on their surface with Ag nanoparticles

“…The similar absorption spectra were earlier reported for CeO 2 [28][29][68][69][70]. Strong ultraviolet absorption capability of cerium oxide is related to the charge transfer from O 2to Ce 4þ ions.…”

Nanoceria synthesis in the KCl‐LiCl salt system: Crystal formation and properties

“…The band gaps of these three powders are shown in Figure B, and the value for c ‐CeO 2 is 3.2 eV, whereas it is 2.7 eV for m ‐CeO 2 and its aged powder. The band gap of ceria is different depending on the synthesis methods and the particle size, Huang et al reported that the band gap of ceria particle was 2.7‐3.4 eV, and in Verma's report bulk ceria's band gap was 3.2 eV. The method to lower the band gap is one or a combination of techniques such as (1) introduction of intrinsic defects into the system, (2) doping by complementary atoms, (3) deposition of plasmonic resonant materials over the system, and (4) developing intrinsic homocomposite of heterophasic, mixed phase/biphasic ceria system .…”

Experimental and first-principles DFT study on oxygen vacancies on cerium dioxide and its effect on enhanced photocatalytic hydrogen production

“…CeO 2 catalyst was prepared by glycine-nitrate combustion method as our preview work [22,23]. The powder was characterized after calcined at 300 °C, 400 °C, 500 °C, 600 °C, respectively.…”