DOI: 10.5061/dryad.r2280gbmr
title: Effect of graphene sheets on the physicochemical properties of nanocrystallite ceria

description: Currently, replacing expensive and short-lived materials for
 supercapacitors based on RuO with more cost-effective and high-performance
 materials that remain operational after a large number of cycles is a
 challenge. Cerium-based materials are the most attractive alternative
 because of the cerium ability to quickly change oxidation state. This work
 proposes the synthesis of nanostructured graphene-ceria composite and
 studies its morphological features arising under the impact of oxygen-free
 graphene. The mechanism of formation of nano-ceria crystallites when the
 sol-gel transition occurs on the surface of graphene sheets is also
 considered. It has been proven that the addition of 0.5–0.6 wt.% graphene
 sheets ensures that nano-ceria is single-phase, while simultaneously
 increasing its dispersity. Using the dilatometry method, it has been
 determined that uniformly distributed sheets of oxygen-free graphene leads
 to a decrease in temperature of the beginning of composite sintering by
 175°C compared to pure nano-ceria, and increases the shrinkage value by 2
 times, which, in turn, should promote better sintering. This composite is
 promising in the development of new materials for small devices and large
 power plants.
description: The dataset was collected through experiments conducted by the
 co-authors. Their interpretation was carried out during the
 discussion.
description: # Effect of Graphene Sheets on the Physicochemical Properties of
 Nanocrystallite Ceria
 [https://doi.org/10.5061/dryad.r2280gbmr](https://doi.org/10.5061/dryad.r2280gbmr) ## Description of the data and file structure Materials are intended for reviewers of the article.  The files present the primary experimental results and characterization protocols for the synthesized samples. All files refer to the samples of pure ceria nanopowder and its analogue with a graphene additive. Designation of samples: CeO2 – nanopowder of pure ceria Graphene-CeO2 ─ ceria nanopowder with graphene additive XRD - x-ray diffraction TEM – transmission electron microscopy HRTEM – high resolution TEM SAED – selected area electron diffraction EELS - electron energy loss spectroscopy EDS – energy dispersive spectrometry **Figure 1.** TEM data for a graphene suspension in DMOA-aqua: a - bright-field image of the sheet, b, c – SAED on the different regions of a sheet, shown in a. The morphology of the synthesized graphene powders and suspensions was studied by TEM using a LEO 912 ab Omega Carl Ziess instrument, which also provided SAED for all samples. A detailed study of the structure of graphene sheets was carried out using HRTEM on a JEM 2010 instrument (JEOL Ltd.) with attachments for characteristic  EELS (GIF Quantum, Gatan Inc.). **Figure 2.** EELS analysis of the suspension (a) and enlarged region above energy loss value 450 eV (b). A detailed study of the structure of graphene sheets was carried out using HRTEM on a JEM 2010 instrument (JEOL Ltd.) with attachment for characteristic EELS (GIF Quantum, Gatan Inc.). **Figure 3.** The impact of the duration of ultrasonic irradiation of graphite on the graphene concentration in suspension at pH value of 3 – data set **Figure 5.** TEM image of a xerogel-intermediate (at 350°C), a precursor of the graphene-ceria composite: bright-field (a,b) and dark-field (c) images, and SAED of the sample area shown in c (d). The morphology of the synthesized composite powders was studied by TEM using a LEO 912 ab Omega Carl Ziess instrument, which also provided SAED for all samples **Figure 6.** TEM data for the graphene-ceria composite calcined at 500°C: bright-field (a,b), dark-field image (c) and SAED (d). The content of graphene in the composite was 0.5 wt%. The morphology of the synthesized composite powders was studied by TEM using a LEO 912 ab Omega Carl Ziess instrument, which also provided SAED for all samples. **Figure 7.** TEM data for pure nano-CeO2: bright-field (a and b) and dark-field (c) images and SAED for the sample area shown in a and c (d). The morphology of the synthesized powders was studied by TEM using a LEO 912 ab Omega Carl Ziess instrument, which also provided SAED for all samples. **Figure 8.** HRTEM images for graphene-ceria composite. A detailed study of the structure of composite powders was carried out using HRTEM on a JEM 2010 instrument (JEOL Ltd.) with attachments for EDS (Inca, Oxford Instruments). **Figure 9.** HRTEM image for graphene-ceria composite (a). The image was obtained using the JEOL JEM-2200FS instrument. **Figure 10.** The results of an EDS analysis of a section of the composite sample shown in Figure 8. A detailed study of the structure of composite powders was carried out using HRTEM on a JEM 2010 instrument (JEOL Ltd.) with attachments for EDS (Inca, Oxford Instruments). **Figure 11.** Raman spectrum of graphene-CeO2 composite nanopowder. The laser excitation line is 532 nm. General view (a) and decomposition of spectrum in the area of ca 300−700 cm−1 into three components (b). The spectrum in the area of ca 200-2000 cm−1 is shown in the Fig.11a.inset. The composites were studied by Raman spectroscopy using lasers with wavelengths of 405, 532 and 785 nm (inViaRaman Microscope, Renishaw, Great Britain). Since the increased structureless luminescent background in the study of nanoscale materials prevents the production of Raman spectra of satisfactory quality, lasers with different wavelengths are used, which will reduce the luminescent background. A backscattering scheme was used to obtain the spectra. **Figure 14.** The curves of shrinkage (red) and shrinkage rate (green) for samples: pure nano-ceria (a) and graphene-ceria composite (b). The dilatometry study of the synthesized nanostructured powders was carried out using a DIL 402 C Netzsch dilatometer (Netzsch, Germany) according to a previously developed method [Trusova EA, Titov DD, Kirichenko AN, Zorin MY. 2020 Effect of graphene sheet incorporation on the physicochemical properties of nano-alumina. New J. Chem. 44, 9046–9052. (doi:10.1039/C9NJ06317J)]. The obtained from nanopowders cylindrical green bodies, with a diameter of 5 mm and a height – 2.5 mm, were used for the study. The thermocouple (tungsten-rhenium alloy) was located near the sample and its temperature was accurately recorded; the second thermocouple (tungsten-rhenium alloy) was in the chamber with the heater. This chamber is separated from the working chamber and filled with argon. The argon flow through the furnaces was 70 mL/min, heating was carried out up to 1650°C at a rate of 5, 10 and 20 °C/min after which cooling was carried out at a rate of 20 °C/min. **XRD_data_pure_CeO2.** XRD results data for pure nano-CeO2 powder **XRD_data_Graphene-CeO2.** XRD results data for graphene-CeO2 composite powder