The ability of the heterojunction between two distinct semiconductors with appropriately matched band gaps to improve the separation of photogenerated electron-hole pairs has been demonstrated to enhance photocatalytic activity. Hence, ZnO/g-C₃N₄ composites have been fabricated by the facile deposition and calcination of ZnO and g-C₃N₄. X-ray photoelectron spectroscopy, powder X-ray diffraction, and Fourier transform infrared spectroscopy confirm the formation of the composite. Scanning electron microscope, transmission electron microscope, and energy-dispersive X-ray spectroscopy morphological analysis reveal that ZnO was homogeneously spread over the g-C₃N₄ surface. UV-vis diffuse reflectance spectroscopy analysis shows the slightly enhanced visible light absorption ability of the composite. Photoluminescence (PL) spectroscopy and electrochemical impedance spectroscopy analysis prove the higher charge separation of the composite during the irradiation of light. The composite shows admirable photocatalytic efficiency in the visible light-driven photocatalytic degradation of an aqueous diclofenac (DFC) solution. The superoxide anion radical (•O₂ ^-) and hydroxyl radical (•OH) act as reactive species during the degradation reaction. Probable reaction mechanisms have been proposed.

Titanium dioxide nanotubes (TNTs) were fabricated via electrochemical anodization process. Photocatalytic hydrogen generation from formic acid solution was investigated using TNTs with simultaneous Rh deposition. The effects of calcination temperature and time for TNTs on hydrogen generation were studied. The maximum hydrogen generation (54 µmol) was observed when using TNTs with a 500 °C calcination temperature and 10 h calcination time under 5 h of black light (352 nm) irradiation. The reusability tests indicated that the TNTs with photodeposited Rh metal (Rh/TNT) had excellent stability up to the fifth cycle for hydrogen generation from formic acid solution. The TNTs were characterized before and after photodeposition of Rh metal via X-ray powder diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and diffuse reflectance spectroscopy (DRS). XRD revealed the presence of optimal anatase–rutile phase ratios in TNTs at 500 °C and 300 °C calcination temperatures. XRD and SEM revealed the deposition of Rh metal on the TNT surface at 300 °C and 500 °C calcination temperatures. It was observed that the light absorption ability of TNTs calcined at 500 °C was greater than that of TNTs calcined at 300 °C. The reaction mechanisms for the formation of TNTs and photocatalytic hydrogen production from formic acid solutions by TNTs with simultaneous Rh deposition were also proposed.

Photocatalytic hydrogen production was studied with a formic acid solution with titanium dioxide (TiO₂) with the aid of simultaneous Rh deposition. The optimum conditions were as follows: Rh loading, 0.1 wt%; formic acid concentration, 1.0%; solution, pH 2.2; temperature, 50 °C. Under the optimum conditions, the photocatalytic hydrogen production with TiO₂ by the simultaneous deposition of Rh was 5.0 mmol g⁻¹, 12.2 mmol g⁻¹ and 16.0 mmol g⁻¹ after 1 h, 3 h and 5 h of irradiation time for black light, respectively. Rh/TiO₂ photocatalysts were characterized by XRD, SEM, photoluminescence spectra, diffuse reflectance spectra and the BET surface area. The reaction mechanism of photocatalytic hydrogen production from formic acid by Rh/TiO₂ was also proposed.

Industrial wastewater containing dye can cause severe destruction to the human immune system as well as the nervous system. The purpose of the present study is to optimize the decolorization of a textile dye Novacron blue on the surface of jackfruit seed powder (JSP). Jackfruit seed can be obtained at a low cost and be used without further purification/chemical treatment to adsorb some pollutants on its surface. About 73% of Novacron blue was adsorbed on the surface of JSP after 60 minutes of contact time. Effects of various physico-chemical parameters such as adsorbent dose, initial dye concentration, pH, temperature, and contact time on the adsorption of Novacron blue have been investigated. The adsorption was found to be increased initially with the adsorbent dose and become maximum at 10 g of the adsorbent. The maximum adsorption capacity was 0.732 mg/g. The decolorization efficiency was inversely proportional to the initial concentration of Novacron blue. Basic medium and low temperature are preferred by the adsorbent for the adsorption of Novacron blue on JSP. Kinetics of adsorption was accomplished with the pseudo-first-order and pseudo-second-order model. Phytotoxic study on Red Amaranth reveals the abolishment of hazardous species from the wastewater.