The Photocatalytic Conversion of Carbon Dioxide to Fuels Using Titanium Dioxide Nanosheets/Graphene Oxide Heterostructure as Photocatalyst

Abstract

Carbon dioxide (CO2) photoreduction to high-value products is a technique for dealing with CO2 emissions. The method involves the molecular transformation of CO2 to hydrocarbon and alcohol-type chemicals, such as methane and methanol, relying on a photocatalyst, such as titanium dioxide (TiO2). In this research, TiO2 nanosheets (TNS) were synthesized using a hydrothermal technique in the presence of a hydrofluoric acid (HF) soft template. The nanosheets were further composited with graphene oxide and doped with copper oxide in the hydrothermal process to create the copper−TiO2 nanosheets/graphene oxide (CTNSG). The CTNSG exhibited outstanding photoactivity in converting CO2 gas to methane and acetone. The production rate for methane and acetone was 12.09 and 0.75 µmol h−1 gcat−1 at 100% relative humidity, providing a total carbon consumption of 71.70 µmol gcat−1. The photoactivity of CTNSG was attributed to the heterostructure interior of the two two−dimensional nanostructures, the copper−TiO2 nanosheets and graphene oxide. The nanosheets−graphene oxide interfaces served as the n−p heterojunctions in holding active radicals for subsequent reactions. The heterostructure also directed the charge transfer, which promoted electron−hole separation in the photocatalyst.

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

“…For TNS, the spectra reveal peaks at 25.63, 38.20, 48.30, 54.10, 55.30, 62.90, 68.93, 70.44, and 75.28°, which are indexed to the {101}, {004}, {200}, {105}, {211}, {204}, {116}, {220}, and {215} planes of TiO 2 anatase (PDF: 00-064-0863). 7 . The shift can be attributed to replacing TiO 2 oxygen with amine nitrogen, which leads to a partial N-dope interaction on TiO 2 .…”

“…8 Our research group has demonstrated the use of TiO 2 /GO composites for CO 2 photoreduction in the aqueous phase 8,9 and gas phase. 7 We studied the effects of transition metal doping 8 and reported excellent photoactivity of copper-doped TiO 2 /GO composites. We demonstrated that the 2D−2D heterostructure composites gave outstanding photoactivity due to excellent electron−hole separation and sufficient engagement from active radicals at the n−p interfaces.…”

“…We demonstrated that the 2D−2D heterostructure composites gave outstanding photoactivity due to excellent electron−hole separation and sufficient engagement from active radicals at the n−p interfaces. 7,9 Amines are a group of chemicals that contain basic nitrogen. They have long been employed in industrial amine scrubbers for CO 2 capture.…”

Recent Advances in Black TiO2 Nanomaterials for Solar Energy Conversion

“…TiO 2 photocatalysts treated at 800 °C in hydrogen atmosphere for 1 h showed higher visible photocatalytic activity for C-H/C-H coupling of dipyrromethanes with azines than commercial TiO 2 (P25) [ 16 ]. TiO 2 nanosheets were proved to exhibit superior photocatalytic activity for CO 2 reduction than the nanoparticle, thanks to its much higher surface area and surface activity [ 17 ]. In addition, the effects of the particle size of TiO 2 on photocatalytic pollutant removal were thoroughly investigated by Kim et al [ 18 ].…”

Controllable Synthesis of MIL-101(Cr)@TiO2 Core–Shell Nanocomposites for Enhanced Photocatalytic Activity

“…The use of fossil fuels produces large amounts of CO 2 and increases the concentration of CO 2 in the atmosphere, − which causes a series of serious environmental problems. Using photocatalysts to convert CO 2 into organic products through solar energy is one of the best ways to solve this problem, like killing two birds with one stone to save our environment. − Various photocatalysts have been explored, including semiconductor materials such as TiO 2 , − Zn 2 GeO 4 , − ZnGa 2 O 4 , − etc.…”