Effect of nickel and rGO on the photocatalytic properties of Co3_ xNixO4 prepared with citric acid and CTAB

This work summarizes the research about Co3_xNixO4 x = 0.0 (0%), 0.01 (1%), and 0.04 (4%) conducted with the addition of reduced graphene oxide, rGO, using two routes: with citric acid R1 (C6H8O7, CA) and cetyltrimethylammonium R2 (C19H42BrN, CTAB) by sol-gel technique. The results show that the composite material -with rGO- enhanced the photocatalytic degradation of methylene blue (MB). According to the results, incorporating rGO into samples with low Ni concentrations of 1% and 4% and processed at 400 degrees C with R1, significantly increased their specific surface area to 31.372 m2.g_ 1 and 84.743 m2.g_ 1, respectively. The XRD technique shows the formation of pure cobalt spinel without associated secondary phases and with complete insertion of Ni into the structure. The presence of CA allows the formation of the oxide at lower temperatures. The results of the magnetic tests suggest that the samples obtained by the two synthesis routes present a paramagnetic behavior. The use of CTAB permits the formation of nanoparticles with low agglomeration. TEM images indicate that the sizes of the nanoparticles obtained in the synthesis are less than 20 nm. Thus, based on Raman spectroscopy, the vibrational modes corresponding to the Co3_xNixO4 structure were studied, identifying a broadening and displacement of the peaks with the addition of Ni. Moreover, the disappearance of the peaks corresponding to rGO and attributed to the coating of Co3_ xNixO4 graphene nanoparticles was observed. The adsorption isotherms show the behavior of a mesoporous textured material. The diffuse reflectance indicates that R2 with a 1.72 eV value obtained the material with the smallest gap. In addition, the process identified that the existence of reduced graphene oxide increases the material's specific surface area, which plays a crucial role in MB degradation, outperforming the 4% Ni sample that degraded 39.65% in a two-hour treatment.

Automated summary

This study summarizes the research on Co3_xNixO4 (x=0.0, 0.01, and 0.04) with the addition of reduced graphene oxide (rGO) using two different routes (R1 and R2). The results demonstrate that the composite material with rGO enhances the photocatalytic degradation of methylene blue (MB). Incorporating rGO into samples with low Ni concentrations significantly increases their specific surface area. XRD analysis confirms the formation of pure cobalt spinel without secondary phases and complete insertion of Ni into the structure. TEM images reveal that the synthesized nanoparticles are smaller than 20 nm. The presence of rGO increases the specific surface area, which is crucial for MB degradation.