In this research work, we reported the synthesis of a spherical-shaped bismuth vanadate (BiVO₄) photocatalyst using a cost-effective, simple, chemical hydrothermal method and studied the effect of deposition temperatures on the structural, morphological, optical properties, etc. The XRD result confirmed the monoclinic scheelite phase of BiVO₄. An XPS study confirmed the occurrence of Bi, V, and O elements and also found that Bi and V exist in +3 and +5 oxidation states, respectively. SEM micrographs revealed the spherical-shaped morphology of the BiVO₄ photocatalyst. Optical investigation showed that the bandgap of the BiVO₄ photocatalyst varied between 2.25 and 2.32 eV. The as-synthesized BiVO₄ photocatalyst was used to study the photocatalytic degradation of crystal violet (CV) dye under visible light illumination. The photocatalytic degradation experiment showed that the degradation percentage of crystal violet dye using BiVO₄ reached 98.21% after 120 min. Mineralization of crystal violet dye was studied using a chemical oxygen demand analysis.

Herein, overall improvement in the electrochemical performance of manganese dioxide is achieved through fine-tuning the microstructure of partially Co-doped manganese dioxide nanomaterial using facile hydrothermal method with precise control of preparative parameters. The structural investigation exhibits formation of a multiphase compound accompanied by controlled reflections of α-MnO₂ as well as γ-MnO₂ crystalline phases. The morphological examination manifests the presence of MnO₂ nanowires having a width of 70–80 nm and a length of several microns. The Co-doped manganese dioxide electrode displayed a particular capacitive behavior along with a rising order of capacitance concerning with increased cobalt ion concentration suitable for certain limits. The value of specific capacitance achieved by a 5% Co-doped manganese dioxide sample was 1050 F g^–1 at 0.5 A g^–1, which was nearly threefold greater than that achieved by a bare manganese dioxide electrode. Furthermore, Co-doped manganese dioxide nanocomposite electrode exhibits exceptional capacitance retention (92.7%) till 10,000 cycles. It shows the good cyclability as well as stability of the material. Furthermore, we have demonstrated the solid-state supercapacitor with good energy and power density.

Titanium oxide (TiO₂) is a potential photocatalyst for removing toxic NO_x from the atmosphere. Its practical application is, however, significantly limited by its low absorption into visible light and a high degree of charge recombination. The overall photocatalytic activity of TiO₂ remains too low since it can utilize only about 4–5% of solar energy. Nitrogen doping into the TiO₂ lattice takes advantage of utilizing a wide range of solar radiation by increasing the absorption capability towards the visible light region. In this work, N-doped TiO₂, referred to as TC, was synthesized by a simple co-precipitation of tri-thiocyanuric acid (TCA) with P25 followed by heat treatment at 550 degrees C. The resulting nitrogen doping increased the visible-light absorption and enhanced the separation/transfer of photo-excited charge carriers by capturing holes by reduced titanium ions. As a result, TC samples exhibited excellent photocatalytic activities of 59% and 51% in NO oxidation under UV and visible light irradiation, in which the optimum mass ratio of TCA to P25 was found to be 10.

We fabricate mesoporous silica/epoxy polymer composites through a solvent evaporation process. The easy penetration of the epoxy polymers into mesopores is achieved by using a diluted polymer solution including a volatile organic solvent. After the complete solvent evaporation, around 90% of the mesopores are estimated to be filled with the epoxy polymer chains. Here we carefully investigate the thermal expansion behavior of the obtained mesoporous silica/polymer composites. Thermal mechanical analysis (TMA) charts revealed that coefficient of linear thermal expansion (CTE) gradually decreases, as the amount of the doped mesoporous silica increases. Compared with spherical silica particle without mesopores, mesoporous silica particles show a greater effect on lowering the CTE values. Interestingly, it is found that the CTE values are proportionally decreased with the decrease of the total amount of the polymers outside the mesopores. These data demonstrate that polymers embedded inside the mesopores become thermally stable, and do not greaty contribute to the thermal expansion behavior of the composites.