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.

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.

Contamination of antibiotics in water is a major cause of antibiotic resistance (ABR) in pathogens that endangers human health and food security worldwide. Ciprofloxacin (CIP) is a synthetic fluoroquinolone (FQ) antibiotic and is reportedly present in surface water at a concentration exceeding the ecotoxicological predicted no-effect concentration in some areas. This study fabricated a CIP sensor using an electropolymerized molecularly imprinted polymer (MIP) of polyaniline (PANI) and poly(o-phenylenediamine) (o-PDA) with CIP recognition sites. The MIP was coated on a reduced graphene oxide (rGO)modified glassy carbon electrode (rGO/GCE) and operated under a differential pulse voltammetry (DPV) mode for CIP detection. The sensor exhibited an excellent response from 1.0 × 10 −9 to 5.0 × 10 −7 mol L −1 CIP, showing a sensor detection limit and sensitivity of 5.28 × 10 −11 mol L −1 and 5.78 μA mol −1 L, respectively. The sensor's sensitivity for CIP was 1.5 times higher than that of the other tested antibiotics, including enrofloxacin (ENR), ofloxacin (OFX), sulfamethoxazole (SMZ), and piperacillin sodium salt (PIP). The reproducibility and reusability of the sensor devices were also studied.