In this paper, a heterogeneous composite catalyst Cu₂O/(001)TiO₂ was prepared by the impregnation-reduction method. The crystal form, highly active facet content, morphology, optical properties, and the photogenerated electron-hole recombination rate of the as-prepared catalysts were investigated. The performance of Cu₂O/(001)TiO₂ was appraised by photocatalytic degradation of ammonia under sunlight and was compared with lone P25, Cu₂O, and (001)TiO₂ at the same reaction conditions. The results showed that 80% of the ammonia concentration (120 ± 3 ppm) was removed by Cu₂O/(001)TiO₂, which was a higher degradation rate than that of pure P25 (12%), Cu₂O (12%), and (001)TiO₂ (15%) during 120 min of reaction time. The reason may be due to the compound’s (Cu₂O/(001)TiO₂) highly active (001) facets content that increased by 8.2% and the band gap width decreasing by 1.02 eV. It was also found that the air flow impacts the photocatalytic degradation of ammonia. Therefore, learning how to maintain the degradation effect of Cu₂O/(001)TiO₂ with ammonia will be important in future practical applications.

In this paper, the Hummer’s method was used to prepare the compound catalyst of reduced graphene and TiO₂ (RGO-P25), and the sand core plate was used as the carrier to provide the theoretical basis for the application of animal environmental purification by exploring the degradation of ammonia in RGO-P25. Characterization results show that the band gap of P25 is reduced from 3.14 eV to 2.96 eV after the combination of RGO, and the recombination rate of the photogenerated electrons and holes also decreased significantly, both resulting in the improvement of ammonia degradation by composite catalysts. Experimental results show that the carrier (sand core plate) and RGO-P25 are effectively stabilized with Si–O–Ti, but the blank core plate carrier could not degrade the ammonia, and its adsorption is not obvious, only 5% ± 1%, under 300 W ultraviolet lamp irradiation, the degradation rates of P25, RGO and RGO-P25 for ammonia at initial concentrations of 119–124 ppm were 72.25%, 81.66% and 93.64%, respectively. P25 dispersed through RGO can effectively adsorb ammonia on the surface to provide a reaction environment and thereby improve its photocatalytic efficiency, thus, endowing the RGO-P25 composites with higher photocatalytic degradation performance than RGO or P25 individually.

{001}TiO₂/TiOF₂ photocatalytic composites with a high activity {001} crystal plane were prepared by one-step hydrothermal methods using butyl titanate as a titanium source and hydrofluoric acid as a fluorine source. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), raman spectroscopy, N₂ adsorption-desorption curve (BET), UV-Vis diffuse absorption spectroscopy (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS), and fluorescence spectroscopy (PL) were used to evaluate the structure, morphology, specific surface area, optical properties, and photocarrier separation ability of {001}TiO₂/TiOF₂. Ammonia nitrogen was taken as the target pollutant, and the degradation performance of the catalyst was investigated. The results show that hydrofluoric acid improves the content of {001} crystal plane of TiO₂ with high activity; it also improves the specific surface area and dispersion of the composite material and adjusts the ratio of {001}TiO₂ to TiOF₂ in the composite material to enhance the absorption capacity of the composite material and reduce the band gap width of the composite material. The degradation rate of ammonia nitrogen by 100 mg F15 is 93.19% when the initial concentration of ammonia nitrogen is 100 mg/L and pH is 10. Throughout the reaction process, the {001}TiO₂/TiOF₂ composite produces superoxide anion radical (·O₂⁻) and hydroxyl radical (·OH) to oxidize NH₃·H₂O and generate N₂ accompanied by a small amount of NO₃⁻ and NO₂⁻.