We utilized a one-step hydrothermal process for the synthesis of precious metal-doped titanium dioxide (TiO 2 )/graphene oxide (GO) composites. The metal-doped TiO 2 /GO composites, including silver–TiO 2 /GO (Ag–TiO 2 /GO), palladium–TiO 2 /GO (Pd–TiO 2 /GO), and copper–TiO 2 /GO (Cu–TiO 2 /GO), were synthesized by mixing a metal precursor, titanium butoxide, and graphene oxide in a water–ethanol mixture in an autoclave hydrothermal reactor. The photocatalytic performance of the composites was tested in the photoreduction of carbon dioxide (CO 2 ) to ethanol. Ag–TiO 2 /GO, Pd–TiO 2 /GO, and Cu–TiO 2 /GO exhibited an ethanol production rate of 109, 125, and 233 μmol/g cat h, respectively. The outstanding performances of Cu–TiO 2 /GO can be attributed to a combined effect of key parameters, including optical band gap, crystallite size, and BET surface area.

The copper-doped sodium dititanate nanosheets/graphene oxide heterostructure (CTGN) was synthesized following a one-step hydrothermal process, exhibiting an outstanding photoactivity in converting CO2 to acetone, methanol, ethanol and i-propanol.

In ethanol production, it is useful to monitor the state of fermentation using a sensor that provides real-time measurement but does not disturb the process. We propose here a tin oxide (SnO2)-reduced graphene oxide (rGO) composite chemiresistive sensor that can be operated on low power and installed in a compact area for the monitoring of ethanol vapor. The sensor exhibited outstanding sensing responses to 29–145 ppm ethanol vapor, providing a sensitivity of 12 ppm−1, a response time of 123 ± 6, recovery time of 128 ± 42 s, and a limit of detection of 3 ppm. The sensor showed good selectivity to ethanol over carbon dioxide, acetic acid and water vapor. The sensing mechanism of the sensor relies on the reaction of ethanol vapor and chemisorbed oxygen species in which the reaction rate increases due to an abundance of the chemisorbed oxygen within n–p heterojunctions of SnO2-rGO.

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