Zirconia has advantageous thermal stability and acid–base properties. The acidity character of ZrO₂ can be enhanced through the sulfation process forming sulfated zirconia (ZrO₂-SO₄). An acidity test of the catalyst produced proved that the sulfate loading succeeded in increasing the acidity of ZrO₂ as confirmed by the presence of characteristic absorptions of the sulfate group from the FTIR spectra of the catalyst. The ZrO₂-SO₄ catalyst can be further modified with transition metals, such as Platinum (Pt), Chromium (Cr), and Nickel (Ni) to increase catalytic activity and catalyst stability. It was observed that variations in the concentrations of Pt, Cr, and Ni produced a strong influence on the catalytic activity as the acidity and porosity of the catalyst increased with their addition. The activity, selectivity, and catalytic stability tests of Pt/ZrO₂-SO₄, Cr/ZrO₂-SO₄ and Ni/ZrO₂-SO₄ were carried out with their application in the hydrocracking reaction to produce liquid fuel. The percentage of liquid fractions produced using these catalysts were higher than the fraction produced using pure ZrO₂ and ZrO₂-SO₄ catalyst.

Rhodamine B (RhB) is extensively used for dyeing purposes, and cannot be completely removed using traditional water treatment technologies. Here, we report for the first time the photodegradation of RhB using nitrogen-doped titanium dioxide (N-TiO₂) on reduced graphene oxide (rGO) composite (N-TiO₂/rGO). The work primarily highlights the synergistic effect of the incorporation of N-TiO₂ and rGO and its kinetic study for the photodegradation of RhB. The N-TiO₂/rGO composite was synthesized by dispersing titanium(IV) isopropoxide and urea, followed by annealing treatment via the hydrothermal method with rGO. Scanning electron microscopy (SEM) images illustrated that N-TiO₂ particles with an irregular round shape and white color were dispersed onto the rGO surface. X-Ray diffraction (XRD) patterns revealed that N-TiO₂/rGO composite showed an anatase phase of TiO₂ with a diffraction peak of 2θ = 25.622°. The gas sorption analysis (GSA) showed that N-TiO₂/rGO had surface area, pore volume, and pore size of 53.393 m²/g, 0.096 cc/g, and 3.588 nm, respectively. The thermogravimetric-differential thermal analysis (TG-DTA) showed an anatase phase of TiO₂ that appeared at a temperature of 200–500 °C, with a weight loss of 2.50%. According to the ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) study, TiO₂, N-TiO₂, and N-TiO₂/rGO had band gap energies of 3.25, 2.95, and 2.86 eV, respectively. The highest photodegradation of RhB was obtained at the optimum condition in pH 2 with a photocatalyst mass of 20 mg and an irradiation time of 90 min. The photocatalytic activity of N-TiO₂/rGO using visible light showed a higher percentage of photodegradation at 78.29%, compared to 44.08% under UV light. The kinetic study of the photodegradation of RhB using N-TiO₂/rGO followed the pseudo-second-order model.

A Pt/nano ZrO₂–SO₄ bifunctional metal–acid catalyst was synthesized using a hydrothermal process.

The nanocrystalline bismuth oxide (Bi₂O₃) was produced utilizing a green combustion process with Mexican Mint gel as the fuel. The powder X-ray diffraction (PXRD) method proved the nanocrystalline nature and Bi₂O₃ nanoparticles (BONPs) in α phase and the average crystalline size of BONPs nanoparticles has been found to be 60 nm. The spherical-shaped structure with bright dot-like spots in the center of the selected area diffraction (SAED) is confirmed by the scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDAX) in conjunction with the transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) demonstrating the crystalline behavior of green NPs. The Kubelka-Monk function was used to analyze diffuse reflectance spectra, and the results revealed that BONPs have a band gap of 3.07 eV. When utilized to evaluate the photocatalytic capabilities of NPs, the direct green (DG) and fast orange red (F-OR) dyes were found to be activated at 618 and 503 nm, respectively. After 120 min of exposure to UV radiation, the DG and F-OR dyes’ photodegradation rate reduced its hue by up to 88.2% and 94%, respectively. Cyclic voltammetry (CV) and electrochemical impedance techniques in 0.1 N HCl were used to efficiently analyze the electrochemical behavior of the produced BONPs. A carbon paste electrode that had been enhanced with BONPs was used to detect the glucose and uric acid in a 0.1 N HCl solution. The results of the cyclic voltammetry point to the excellent electrochemical qualities of BONPs. Bi₂O₃ electrode material was found to have a proton diffusion coefficient of 1.039 × 10⁻⁵ cm²s⁻¹. BONP exhibits significant potential as an electrode material for sensing chemicals like glucose and uric acid, according to the electrochemical behavior.