In this study, photocatalysis was employed to degrade a wastewater pollutant (AB-29 dye) under visible light irradiation. For this purpose, nitrogen (N)- and neodymium (Nd)-doped TiO₂ nanoparticles were prepared using the simple hydrothermal method. X-ray diffraction (XRD) revealed an anatase phase structure of the Nd-N/TiO₂ photocatalyst, whereas properties including the surface morphology, chemical states/electronics structure and optical structure were determined using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–visible (UV–vis.) and photoluminescence (PL) spectroscopies. Photocatalytic testing of the prepared nanomaterials was performed to remove acid blue-29 (AB-29) dye under visible-light exposure. The prepared Nd-N/TiO₂ nanoparticles demonstrated a superior photocatalytic activity and the decolorization efficiency was about 92% after visible-light illumination for 1 h and 20 min, while N/TiO₂, Nd/TiO₂ and TiO₂ only showed a 67%, 43% and 31% decolorization efficiency, respectively. The enhanced photocatalytic activity of the Nd-N/TiO₂ photocatalyst was due to a decrease in the electron/hole’s recombination and the increased absorption of TiO₂ in the visible range. The reusability results showed that the average photocatalytic activity decrease for all the samples was only about 16% after five consecutive cycles, indicating a good stability of the prepared nanomaterials. Moreover, the radical scavenging activity of the prepared nanomaterials was evaluated using the DPPH method. The novel Nd-N/TiO₂ exhibited a higher antioxidant activity compared to all the other samples.

Using sustainable photocatalysts, photocatalytic degradation has emerged as one of the viable strategies to combat water pollution through eco-friendly and cost-effective means. Visible-light-active Ag₃PO₄/Mn-ZnO nanocomposite photocatalysts were produced in this study using a simple hydrothermal method and varied concentrations of Ag₃PO₄ to Mn-ZnO ranging from 0 to 5 wt percent. X-ray diffraction, scanning electron microcopy, energy-dispersive X-ray, transmission electron microscopy, UV–visible spectroscopy, Fourier transform infra-red spectrophotometer, and photoluminescence spectroscopy were used to examine the structural, morphological, and optical properties of synthesized materials. Visible light was used to test the photocatalytic activity of produced Ag₃PO₄/Mn-ZnO photocatalysts for the breakdown of tetracycline (TC) hydrochloride. In comparison to the other samples, the 3% Ag₃PO₄/Mn-ZnO nanocomposite exhibited superior activity as a result of improved visible light absorption and suppressed charge carrier recombination. In addition, this sample demonstrated good stability of TC in an aqueous environment after five consecutive cycles. This research will enhance the scope of photocatalysis for environmental applications.

Heterostructure BiVO₄/Bi₂O₃ nanocomposites with enhanced visible light activity are effectively synthesized through an easiest and single step hydrothermal route, using bismuth subnitrate and ammonium meta-vanadate as main raw materials in existence of citric acid. The phase and surface structure, topography and optical properties of synthesized composites are characterized by XRD, SEM, EDX, FTIR, UV–Visible and PL spectroscopy. It was found that 5%BiVO₄/Bi₂O₃ (BOBV-5) nanocomposite exhibit excellent photocatalytic performance for rhodamine B dye degradation and tetracyclic under irradiation of visible light as compared to single component i.e. BiVO₄. The increased photocatalytic activity should be ascribed for making p–n heterojunction among p-type Bi₂O₃ and n-type BiVO₄. This p–n heterojunction successfully reduce the recombination of photogenerated charge carriers. Furthermore, the BOBV-5 novel photocatalyst shows good stability in constructive five cycles and photocatalytic activity is best for conquering photo corrosion of a photocatalysts. To explain charge migration route, whole photocatalytic mechanism was described in terms of energy band structures. Furthermore, the present work is helpful effort for design of new visible light photocatalytic materials with heterojunction structures.