Effective CO₂ Capture and Selective Photocatalytic Conversion into CH₃OH by Hierarchical Nanostructured GO–TiO₂–Ag₂O and GO–TiO₂–Ag₂O–Arg

Abstract

The attenuation of greenhouse gases, especially CO 2 , as one of the main causes of global warming and their conversion into valuable materials are among the challenges that must be met in the 21st century. For this purpose, hierarchical ternary and quaternary hybrid photocatalysts based on graphene oxide, TiO 2 , Ag 2 O, and arginine have been developed for combined CO 2 capture and photocatalytic reductive conversion to methanol under visible and UV light irradiation. The material's band gap energy was estimated from the diffuse reflectance spectroscopy (DRS) Tauc analysis algorithm. Structural and morphological properties of the synthesized photocatalysts were studied using various analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The calculated band gaps for GO−TiO 2 −Ag 2 O and GO−TiO 2 − Ag 2 O−Arg were 3.18 and 2.62 eV, respectively. This reduction in the band gap showed that GO−TiO 2 −Ag 2 O−Arg has a significant visible light photocatalytic ability. The investigation of CO 2 capture for the designed catalyst showed that GO−TiO 2 −Ag 2 O−Arg and GO−TiO 2 −Ag 2 O have high CO 2 absorption capacities (1250 and 1185 mmol g −1 , respectively, at 10 bar and 273 K under visible light irradiation). The amounts of methanol produced by GO−TiO 2 −Ag 2 O and GO−TiO 2 −Ag 2 O−Arg were 8.154 and 5.1 μmol•gcat 1 •h −1 respectively. The main advantages of this study are the high efficiencies and selectivity of catalysts toward methanol formation. The reaction mechanism to understand the role of hybrid photocatalysts for CO 2 conversion is deliberated. In addition, these catalysts remain stable during the photocatalytic process and can be used repeatedly, proving to be enlightening for environmental research.

Alkanolamine-Grafted and Copper-Doped Titanium Dioxide Nanosheets–Graphene Composite Heterostructure for CO2 Photoreduction

“…Bandgap reduction after alkanolamine modification is attributed to an N-dope effect on the TiO 2 , which enhances electron transition from the valence band to the conductive band. 6,33 For the composite samples (Figure 6B 7). In our case, basicity is essential, as it quantifies basic sites on the catalyst and correlates to their interactions with acidic CO 2 .…”

“…The composite yielded methanol as the only product at 20.39 μmol/g CAT /h. 33 The team of Andrade used triethylamine-doped TiO 2 nanoparticles, triethylamine-doped TiO 2 / carbon nanotubes (CNT), and triethylamine-doped TiO 2 / rGO for the gas-phase CO 2 photoreduction. The catalysts produced methane and CO at 1.5 and 3.5, 0.2 and 0.75, and 0.1 and 3.9 μmol/g CAT /h, respectively.…”

Photocorrosion Inactivation of Ag2O/TiO2 Photocatalysts and the Inhibition Effect of Alkaline Conditions on the Inactivation

“…Due to the instability and photosensitivity of Ag 2 O, it often requires combination with other catalysts to enhance its performance . Titanium dioxide (TiO 2 ) is an N-type semiconductor with a band gap width of approximately 3.2 eV.…”

“…19 T h i s c o n t e n t i s Due to the instability and photosensitivity of Ag 2 O, it often requires combination with other catalysts to enhance its performance. 20 Titanium dioxide (TiO 2 ) is an N-type semiconductor with a band gap width of approximately 3.2 eV. Because of its high oxidation capacity and strong chemical stability, TiO 2 is frequently used in combination with Ag 2 O to obtain the Ag 2 O/TiO 2 photocatalyst.…”

Recent developments in polysaccharide and lignin-based (nano)materials for CO2 capture

“…To achieve this, many solutions are being studied, including the use of solid adsorbents. [10][11][12][13][14][15][16] There are several CO 2 capture processes ( post-combustion capture, precombustion capture, or oxy-fuel combustion) the main ones being precombustion and post-combustion. Although post-combustion is the most restrictive solution in terms of separation due to the low concentration of CO 2 , it nevertheless remains the most applicable from an industrial point of view since it does not require any modification of the equipment.…”