•Novel Z-scheme SnO2−x/g-C3N4 composites are prepared and tested.•SnO2−x/g-C3N4 composite degrades RhB 8.8 times faster than g-C3N4 under visible light.•SnO2−x/g-C3N4 composites also show high activity in photocatalytic CO2 reduction.•The Z-scheme mechanism is verified by reactive species trapping experiment.Highly efficient SnO2−x/g-C3N4 composite photocatalysts were synthesized using simple calcination of g-C3N4 and Sn6O4(OH)4. The synthesized composite exhibited excellent photocatalytic performance for rhodamine B (RhB) degradation under visible light irradiation. The optimal RhB degradation rate of the composite was 0.088 min−1, which was 8.8 times higher than that of g-C3N4. The SnO2−x/g-C3N4 composite also showed high photocatalytic activity for CO2 reduction and photodegradation of other organic compounds. Various techniques including Brunauer–Emmett–Teller method (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL) and an electrochemical method were applied to determine the origin of the enhanced photoactivity of SnO2−x/g-C3N4. Results indicated that the introduction of SnO2−x on g-C3N4 increased its surface area and enhanced light absorption performance. More importantly, a hetero-junction structure was formed between SnO2−x and g-C3N4, which efficiently promoted the separation of electron–hole pairs by a direct Z-scheme mechanism to enhance the photocatalytic activity. This study might represent an important step for the conversion of solar energy using cost-efficient materials.

Hydrolysis of chitosan in ionic liquids was carried out under microwave irradiation (MW) using sulfonic acid-functionalized ionic liquids (SFILs) as catalysts. The effect of microwave power, irradiation time, dosage of SFILs and DMSO was investigated by orthogonal tests. Under the optimal reaction conditions, the yield of total reducing sugars (TRS) reached over 90% within 2 min. The viscosity-average molecular weight of degraded chitosan was determined by viscosity method. The structures of the original and degraded chitosan were characterized by Fourier-transform infrared (FTIR) spectra, X-ray powder diffraction (XRD) analysis and carbon-13 nuclear magnetic resonance spectroscopy (13C NMR). The influence of microwave power and irradiation time on the TRS and Mv was further studied. This method can dramatically reduce reaction time.

This paper presents a novel visible-light-driven catalyst, a SO42–/MoOx/MgF2 composite, which was synthesized by a simple solution method. Multiple techniques, including Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS) were applied to investigate the physical and photophysical properties of the catalysts. The photocatalytic activities were evaluated in the degradation of acetone in gas phase. In the photodegradation of acetone, the highest conversion was obtained over a catalyst containing 5 mol % molybdenum. The XRD and Raman characterizations indicate that the molybdenum oxide was highly dispersed in the MgF2 matrix. These MoOx species might be the active sites of the catalysts, which is the reason for the visible-light response of the composite catalyst. The MgF2 matrix acts to isolate the MoOx species and retard the electron–hole pair recombination. When the molybdenum concentration is >5 mol %, crystalline MoO3 phase was observed. The large MoO3 particle would decrease the separation efficiency. Thus, the photocatalytic activity was reduced. Besides the molybdenum concentration, the calcination temperature also shows a great effect on the activity. A sulfated 5 mol % MoOx/MgF2 catalyst that was calcined at 350 °C showed the highest photocatalytic activity. Based on the results of the characaterization, the origin of the high activity was discussed. The light absorption ability and the MoOx size effect are considered as the key factors.

This article presents a novel visible-light-driven catalyst, an LaVOx composite that was prepared from La(NO3)3 and NH4VO3 solutions. The visible-light-induced photocatalytic activity of this composite was evaluated by the degradation of acetone. Results indicate that the LaVOx composite exhibits high activity for acetone photodegradation. The highest acetone conversion (93.1%) was obtained with the La1V1.5Ox catalyst. Its photo-activity and ability for complete oxidation could be enhanced further by doping with a small amount of the metal platinum. Physical and photophysical properties of the LaVOx composite catalysts were evaluated by X-ray diffraction (XRD), the Brunauer–Emmett–Teller (BET) method, Raman spectroscopy (Raman), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. Based on the results of this investigation, the coupling effect of m-LaVO4 and V2O5 was identified as generating the high activity in catalysis.Graphical abstractResearch highlights► V2O5–LaVO4 composite is a novel visible-light driven catalyst. ► The LaVOx composite shows high activity for acetone degradation under visible light irradiation. ► The coupling effect of m-LaVO4 and V2O5 is the origin of the high activity.

The Zr-Ni-O catalyst prepared by the sol-gel method exhibits a significantly enhanced ethylene selectivity and ethane cleavage-resistant ability for the ODHE reaction. The characterization results by XRD, XPS and TPR indicate that a relative strong interaction exists between ZrO2 and NiO.

Nickel oxide was prepared by modified sol–gel method and spherical NiO nanoparticles were obtained. The factors that influence the physical property of NiO nanoparticles were investigated mainly through the use of SEM, BET and XRD. It revealed that calcination temperature of the precursor and the pH value of the solution significantly affected the particle size and surface area of the synthesized nanosized NiO powders. The ratio of citric acid to nickel nitrate and the heating rate of calcinations were also important to the physical property of nanoscaled NiO. The length of calcination time has a minor effect on it.