Construction of ZnTi-LDH nanosheets with exposed hydroxyl groups and their photocatalytic O2/CO2-toluene to benzaldehyde dataset

I. Catalyst CharacterisationA series of characterisation methods were used to characterise the physicochemical and optical properties of the catalysts, and the specific experimental steps, parameter settings and instrument models are as follows:1. X-ray diffraction analysis (XRD)The crystal structure of the samples was determined by XRD-7000S/L X-ray diffractometer (XRD) of Shimadzu Corporation (Japan). For the test, 500 mg of catalyst was weighed and placed on a carrier sheet and compacted with a transparent glass sheet. Test conditions: Cu α-rays (λ = 0.154178 nm), 30.0 kV, 10.0 mA, with a step size of 0.02° and a scanning range of 5°~80° were used.2. Fourier transform infrared spectroscopy analysis (FT-IR)The infrared spectra (FT-IR) of the catalysts were measured by a Tensor 27 Fourier Transform Infrared Spectrometer from Bruker, Germany, to characterise the functional group structure of the samples. Test conditions: the spectroscopic grade potassium bromide was dried in an oven at 60 ℃ for 6 h in advance, followed by thorough grinding of the catalyst with the dried potassium bromide at a mass ratio of 1:200, and finally pressed. The number of scans was 32 and the resolution was 4%.3. Specific surface area and pore size analysis (BET)The specific surface area, pore distribution and gas adsorption of the catalysts were measured by an ASAP 2460 Specific Surface Area and Pore Analyzer from Micromeritics, USA. Test conditions: vacuum degassing at 423.15 K for 8-10 h, followed by inflation for 20 s. Nitrogen adsorption and desorption was carried out by liquid nitrogen at a controlled temperature of 77 K and a relative pressure of P/P0=0~1.4. Scanning electron microscope analysis (SEM)The morphological characteristics of the catalysts were obtained by scanning electron microscopy (SEM) observation with a SU8010 model from Hitachi, Japan. Test conditions: 10 mg of catalyst was uniformly dispersed onto the conductive adhesive, followed by gold spraying, natural drying and then on-board vacuum for testing with an accelerating voltage of 200 KV.5. X-ray photoelectron spectroscopy (XPS)The chemical element composition and valence state of the catalyst surface were analysed by X-ray photoelectron spectroscopy (XPS) with an Escalab 25 model from ThermoFisher Scientific, USA. The test conditions were: Al-K α as the excitation source (1486.6 eV) and C1s (284.8 eV) to correct the binding energy. The post-test data were fitted and analysed using Avantage 5.9931 software developed by Thermo Fisher, USA.6. Solid-state nuclear magnetic resonance analysis (SSNMR)The 1H SSNMR profiles of the catalysts were obtained by testing on an Avance Neo 400WB solid state NMR spectrometer from Bruker, Germany. A 4 mm MAS probe was used for the test and the post-test data were analysed using MestReNova software.7. Electrochemical performance testIn this experiment, the transient photocurrent (IT) and electrochemical impedance (EIS) of the samples were determined by the CEL-HXF300 xenon lamp light source (AM1.5G, 300 W) from Beijing CEC Jinyuan and the CHI 660E electrochemical workstation from Shanghai Chenhua.Preparations before the determination: The fluorine-doped tin dioxide conductive (FTO) glass was sonicated in isopropanol, anhydrous ethanol, and deionised water sequentially for 15 min, and then dried naturally and prepared for use. 10 mg of catalyst was weighed and mixed with 1 mL of deionised water, 1 mL of isopropanol and 5 μL of Nafion, and the dispersion of catalyst was obtained after sonication for 30 min. A pipette gun was used to pipette 100 μL of the dispersion and uniformly cover the conductive surface of a 3 cm2 FTO glass.Configuration of electrolyte:(1) 1.42 g of anhydrous sodium sulfate was weighed and added into 100 mL of deionised water and stirred magnetically for 5 min to obtain the anhydrous sodium sulfate electrolyte for testing the transient photocurrent;(2) 1.7 g of potassium ferricyanide, 0.132 g of potassium ferrocyanide and 0.60 g of KCl were weighed and added into 80 mL of PBS buffer solution, and the electrolyte was obtained after magnetic stirring for 5 min to test the electrochemical impedance.During the test, the conductive side of the FTO glass was oriented towards the xenon light source, the counter electrode (platinum sheet) was placed behind it, the height of the electrode was adjusted so that it did not touch the bottom of the cup, and the working electrode was maintained at a distance of 10 cm from the light source.8. Ultraviolet-visible diffuse reflectance spectroscopy analysis (UV-Vis)The light absorption of the catalysts was measured by UV-2600 UV-Vis spectrometer of Shimadzu Company, Japan, with BaSO4 powder as reference, scanning speed of medium, scanning interval of 1.0, and absorption wavelengths of 200-800 nm. The resulting spectra were further processed to obtain the semiconductor bandwidths.9. Electron paramagnetic resonance spectroscopy (EPR)Detection of free radicals was carried out by an electron paramagnetic resonance spectroscopy (EPR) instrument model AEM plus-6/1 from Bruker, Germany. For the detection of hydroxyl radical (·OH), 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was used as a spin trapping agent, 10 mg of catalyst was weighed and placed in a 5 mL centrifuge tube, and a pipette gun pipetted 1 mL of ultrapure water and 10 μL of DMPO in a centrifuge tube and shook well. The capillary was aspirated with liquid, the bottom of the capillary was plugged with sealing clay and placed in the NMR tube for subsequent testing. For the detection of superoxide radicals (·O2-), simply replace the 1 mL of ultrapure water with 1 mL of anhydrous methanol as described above, and keep the rest of the sample preparation steps the same as those for the testing of hydroxyl radicals.10. Chromatography-mass spectrometry (GC-MS)Agilent 7890A+5975C gas chromatograph (GC-MS) from Agilent (USA) was used to complete the mass spectrometry analysis of the isotope labelling experiments. An HP-5 column was used with automatic injection and run at 300 ℃ for 30 min with a split ratio of 30:1.11. In situ infrared spectroscopyAn INVENIO-S in situ infrared spectrometer from Bruker, Germany was used for the test. Test conditions: the catalyst was purged with argon for 1 h to remove surface impurities, and then adsorbed in a dark environment for 30 min, followed by turning on a 300 W xenon lamp to start the reaction test.Ⅱ. Evaluation of catalyst performanceThe photocatalytic oxidation of toluene was carried out using a photocatalytic reaction device of Beijing CEC Jinyuan CEL-HPR100S+. The experimental steps were as follows: firstly, 50 mg of photocatalyst and 5 mL of toluene were mixed in a 100 mL polytetrafluoroethylene reactor liner. Thereafter, the liner was sealed and purged sequentially with N2 and O2, and after the purging was completed, the O2 pressure was adjusted to x MPa, and then the CO2 charging was continued until the pressure of the reactor reached 1 MPa, and it was sealed and stirred for half an hour under dark conditions. (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0) Finally, the light source of xenon lamp (λ ≥ 320 nm) of Beijing Zhongguo Jinyuan CEL-HXF300 was turned on to maintain the reaction temperature at 50 ℃. After 12 h of illumination, the gaseous product was retained in the photoreactor, and the catalyst-containing liquid in the kettle was separated using a centrifuge, and the collected supernatant was the liquid product, and the yields and selectivities of the gaseous and liquid products were calculated separately. Qualitative and quantitative analyses of the products were carried out by a BFRL-3420A gas chromatograph with a chromatographic inlet temperature of 230 ℃, thermal conductivity detector (TCD) and hydrogen flame ionisation detector (FID) temperatures of 100 ℃ and 230 ℃, and an auxiliary temperature of 380 ℃, respectively. For on-line determination of gaseous products, the column temperature was 70℃. For the determination of liquid products, the column temperature was increased from 120℃ to 180℃ at a rate of 10℃·min-1 .Ⅲ. Free radical burst experiment2,2,6,6-tetramethylpiperidine N-oxide (TEMPO), tert-butanol (TBA), 2,6-di-tert-butyl-4-methylphenol (BHT), p-benzoquinone (BQ), and ammonium oxalate ((NH4)2C2O4) were used as the bursting agents for all the free radicals, hydroxyl radical (·OH), carbon-based radicals (·R), superoxide radicals (·O2-), and photogenerated holes (h+) bursting agents. The free radical bursting experiments were performed by adding 1.03 mmol of the bursting agent after 50 mg of photocatalyst and 5 mL of toluene in a sealed liner, and the rest of the conditions were kept the same as the catalytic activity test conditions described above.