ETS‑10 Modified with CuxO Nanoparticles and Their Application for the Conversion of CO2 and Water into Oxygenates

Abstract

Photocatalytic reactions to convert CO 2 and H 2 O into solar fuels using only solar irradiation have been investigated in this work. For this purpose, titanosilicate ETS-10 was decorated with Cu 2 O and CuO nanoparticles and their properties were analyzed by different techniques. The final materials were applied in photoreduction of CO 2 in gas phase under 20 h of solar irradiation. In the final, the products oxygen, acetic acid, formaldehyde and methanol were detected by chromatographic techniques. Photoluminescence and electrochemical studies indicate the interaction between Cu x O nanoparticles and Ti-O-Ti-O on the surface of ETS-10, corroborating with the results obtained in the photocatalytic experiments. The best CO 2 photoconversion efficiencies into methanol were obtained when using ETS-10/Cu x O compared to pure ETS-10. Another important finding in this study is the fact that the reactions were carried out in the gas phase and no scavenge donors were employed.Keywords: CO 2 photoreduction, ETS-10 photocatalyst, oxygenated products, copper oxide, solar irradiation IntroductionIn the last 40 years, CO 2 emissions from fossil fuel combustion and industrial processes contributed with about 78% of the total greenhouse gases (GHG) emissions. 1 Different methods to consume CO 2 have been investigated, such as thermochemical conversion, 2-4 electrochemical reduction, [5][6][7] and photocatalytic reduction of CO 2 and water into hydrocarbons or solar fuels. [8][9][10] The use of solar energy has been highlighted as an alternative to obtain clean energy while simultaneously reducing the CO 2 concentration in the atmosphere. 11 Many chemicals are reported to be produced from water and CO 2 : formic acid, 12,13 acetic acid, 14,15 formaldehyde, 16 methanol [17][18][19] and methane. 20,21 Using a combination of metaloxides and co-catalysts we have already demonstrated the feasibility to produce both methane and methanol. 22 The first and principal step in CO 2 reduction is the oxidation of H 2 O molecules into oxygen and protons (equation 1), following the sequence described in equations 1-5. 23 Several works report the conversion to oxygenated chemicals by using sacrificial compounds, such as NaOH, 24 Titanosilicate ETS-10 (Engelhard titanium silicate) was first reported in the literature by Chapman and Roe 28 in 1990, however its structure was elucidated only in 1994 by Anderson et al. 29 using sophisticated techniques as highresolution transmission electron microscopy (HRTEM), nuclear magnetic resonance (NMR) and molecular simulations. The most interesting feature is that the ETS-10 contains a periodic structure of quantum semiconductor wires of [-O-Ti-O-Ti-] formed by TiO 6 octahedra isolated along the structure. The pores (ca. 0.67 nm diameter) run along [100] and [010] directions. [30][31][32][33] These properties make ETS-10 unique, because a short Ti-O bond length (1.71-2.11 Å) along the axial direction would not be possible outside of a zeolite framework. 34 This material absorbs ETS-10 Modified with Cu ...

Boost the photocatalytic hydrogen production of the nanocomposites conducting polypyrrole modified with metal oxide (CuO)

“…The decrease in optical energy gap is due to the interaction between CuO nanoparticles and PPy, which causes a variation in the polymer disorder degree, leading to the creation of polymer frame changes. As a result, these defects boost the localized states inside the energy gap, decreasing the band gap [52]. The developed photoelectrode PPy/CuO nanocomposite film was used in an electrochemical hydrogen production process using 3 electrode cell.…”

“…The efficiency of the prepared photoelectrode is related to this easy transfer of an electron from the PPy to CuO materials for additional reaction with the sewage water, where these electrons are the main factor for the hydrogen generation reaction [58]. With increasing these electrons, the liberated hydrogen gas increase, so the J ph represents the electrochemical reaction rate [59]. Additionally, to demonstrate the stability of PPy/CuO film after photocatalytic reaction, the XRD pattern of PPy/CuO film before and after reaction was performed as shown in figure 8(b).…”

Dual photocatalysis for CO2 reduction along with the oxidative coupling of benzylamines promoted by Cu/Cu2O@g-C3N4 under visible irradiation

“…For Cu/Cu 2 O, two emission bands at 437 and 459 nm are obtained because of the scattering at the surface and crystal defects introduced during the crystal growth in the semiconductor. 45 In CuCN-1.5, the incorporation of Cu/Cu 2 O on the CN surface quenches the emission effectively, resulting in the least intense PL band compared to CN and Cu/Cu 2 O, representing the highest separation of charge carriers with minimum recombination to provide efficient photocatalytic activity.…”

Hydrothermal Synthesis and Characterization of Titanosilicate ETS-10: Preparation for Research Integrated Inorganic Chemistry Laboratory Course

“…This is in agreement with prior reports on ETS-10. 26,27 The band-edge corresponds to the electron transition between the O(2p) → Ti(3d) in the •••Ti−O−Ti−O−Ti••• chains in the ETS-10 structure. Students were able to link the observation of this charge-transfer transition with their knowledge from lecture on semiconductors and band theory as reported in their Techniques Pages on this topic.…”

“…The framework of ETS-10 contains well-defined monatomic semiconductor ···Ti–O–Ti–O–Ti··· chains, giving rise to a bandgap energy ( E g ) in the range of ∼3.8–4.03 eV, varying with the crystal quality as well as the method for the determination of the bandgap energy. ETS-10 has attracted much attention to be used in both traditional (e.g., catalysis, , gas separation, − adsorbent, , ) and advanced applications (e.g., photocatalysis − , ) due to its inherent microporosity, pore regularity, and the presence of stoichiometric amounts of titanium in the silicate framework.…”