High performance W-doped TiO2 nanoparticles/reduced graphene oxide (W-TiO2/RGO) composites are successfully synthesized through a facile solvothermal method. During this process, TiO2 was doped with W6+ to generate W-TiO2 nanoparticles, and graphene oxide (GO) was reduced to reduced graphene oxide (RGO), which was uniformly covered with a large number of W-TiO2 nanoparticles. The prepared samples were characterized by various analytical and spectroscopic techniques, including transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), specific surface areas (BET) and photoluminescence (PL) spectroscopy. The photocatalytic properties of the prepared samples were evaluated by the photodegradation of methylene blue (MB) as a model pollutant under visible light irradiation. The results confirmed that TiO2 was doped with W6+ and showed the graphene nature of RGO in W-TiO2/RGO composites. Additionally, it was found that W6+ doping could improve the photoresponse of TiO2 nanoparticles under visible light irradiation and graphene could provide conductive electron channels for the separation of electrons and inhibit the recombination of electrons and holes, hence further improving the response of W-TiO2 nanoparticles under visible light irradiation. The W-TiO2/RGO composites exhibited a much higher photocatalytic activity than mono-modified or non-modified composites and the degradation rate of the W-TiO2/RGO composites toward MB could reach up to 99.8% in 90 min. No obvious inactivation has been observed in durability experiments. The mechanism of enhanced photocatalytic activity, which arose from the synergistic effect of W6+ doping and graphene incorporation, was also discussed.

In this study, a hydrothermal method was employed to synthesize Fe3+-doped TiO2 nanowires (Fe-NWs) followed by the fabrication of graphene/Fe3+-doped TiO2 nanowire composites (GR/Fe-NWCs). Graphene oxide (GO) was reduced to reduced graphene oxide (RGO), which was uniformly covered with a large number of anatase Fe-NWs simultaneously. As controls, TiO2 Degussa P25 nanoparticles (NPs) were converted to TiO2 nanowires (NWs) by an alkaline hydrothermal process, and graphene/TiO2 nanoparticle composites (GR/NPCs) and graphene/TiO2 nanowire composites (GR/NWCs) were also synthesized by the hydrothermal method. The obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, electron spin resonance (ESR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results confirmed the graphene nature of RGO in the GR/Fe-NWCs and Fe3+ doping into NWs. Additionally, it was found that Fe3+ doping could improve the response of TiO2 nanowires under visible light irradiation and that Fe-NWs have more uniform dispersion on graphene with less agglomeration in comparison with NPs, resulting in more direct contact between TiO2 and graphene, and hence further improved electron–hole pair separation and transportation. The photocatalytic performance of GR/Fe-NWCs was evaluated for the photodegradation of methylene blue (MB) under visible light. The GR/Fe-NWCs showed the highest photocatalytic activity among the tested photocatalysts, with about a 3-fold increase in photocatalytic efficiency over NPs. The mechanism of high photocatalytic activity was also discussed.

l-Tryptophan functionalized graphene oxide (GO/l-Trp) was successfully synthesized via the nucleophilic substitution reaction. Its structure was characterized and the performances of GO/l-Trp in the sorption of Cu(II) and Pb(II), including the influence of contact time, initial pH of solution, temperature of the system, and initial metal concentration, were explored. The studies indicated that GO/l-Trp exhibited enhanced sorption capacities for Cu(II) and Pb(II) at the initial pH of 5 and 4, respectively, due to the increased sorption sites. The sorption of Cu(II) and Pb(II) were nearly completed within 40 min and fitted better with Lagergren pseudo-second-order kinetic model, indicating that Cu(II) and Pb(II) sorption on GO/l-Trp were chemical interactions. Langmuir model was more suitable to describe the sorption processes and sorption capacities were 588 mg·g–1 and 222 mg·g–1 for Cu(II) and Pb(II), respectively. Thermodynamic studies revealed that sorption were exothermic and spontaneous. Moreover, it also showed that GO/l-Trp could be reused after desorption, suggesting potential application in wastewater treatment.

Well-defined and monodisperse dendritic platinum nanoparticles (DPNs) are successfully prepared by a rapid, one-step, and efficient route with high yield in aqueous solution, wherein neither organic solvents nor surfactants are employed, ensuring the as-made DPNs definitely have “clean” surfaces, allowing them to exhibit high activity for both methanol oxidation and p-nitrophenol reduction. This proposed strategy for simple and facile preparation of “clean” metal nanocatalysts paves the way for accurately evaluating and further improving their intrinsic catalytic activity.

Asymmetric reduction of α-hydroxy aromatic ketones was carried out by using carrot enzymes system, yielding corresponding chiral vicinal diols with special functional groups. The optimum reaction conditions were obtained after investigation of various influencing factors. Chiral aryl vicinal diols were produced with good yields and excellent enantiomeric excesses under appropriate conditions. Meanwhile, the steric factors and electronic effects of the substituents on the aromatic ring were shown to have an interesting influence on both yield and enantioselectivity.

A reaction of α-bromo aromatic ketones in water with microwave irradiation gave the corresponding α-hydroxy aromatic ketones in good yields. The use of microwaves was found to significantly improve yields and shorten the reaction time. This reaction afforded a very clean, convenient method for the synthesis of α-hydroxy aromatic ketones.

The enantioselective reduction of acetophenone analogues catalyzed by carrot and celeriac was performed in moderate conversions and excellent enantiomeric excesses. The steric factors and electronic effects of the substituents at the aromatic ring were found to significantly affect the efficiency of the enantioselective reduction of acetophenone analogues, while they had a little effect on the enantioselectivity of acetophenone analogues reduction. It was also found that the conversions of acetophenone analogues reduction at 33 °C by means of both biocatalysts were three times as great as those at room temperature.

In this study, a hydrothermal method was employed to synthesize Fe3+-doped TiO2 nanowires (Fe-NWs) followed by the fabrication of graphene/Fe3+-doped TiO2 nanowire composites (GR/Fe-NWCs). Graphene oxide (GO) was reduced to reduced graphene oxide (RGO), which was uniformly covered with a large number of anatase Fe-NWs simultaneously. As controls, TiO2 Degussa P25 nanoparticles (NPs) were converted to TiO2 nanowires (NWs) by an alkaline hydrothermal process, and graphene/TiO2 nanoparticle composites (GR/NPCs) and graphene/TiO2 nanowire composites (GR/NWCs) were also synthesized by the hydrothermal method. The obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, electron spin resonance (ESR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results confirmed the graphene nature of RGO in the GR/Fe-NWCs and Fe3+ doping into NWs. Additionally, it was found that Fe3+ doping could improve the response of TiO2 nanowires under visible light irradiation and that Fe-NWs have more uniform dispersion on graphene with less agglomeration in comparison with NPs, resulting in more direct contact between TiO2 and graphene, and hence further improved electron–hole pair separation and transportation. The photocatalytic performance of GR/Fe-NWCs was evaluated for the photodegradation of methylene blue (MB) under visible light. The GR/Fe-NWCs showed the highest photocatalytic activity among the tested photocatalysts, with about a 3-fold increase in photocatalytic efficiency over NPs. The mechanism of high photocatalytic activity was also discussed.