TiO₂ is a semiconductor material with high chemical stability and low toxicity. It is widely used in the fields of catalysis, sensing, hydrogen production, optics and optoelectronics. However, TiO₂ photocatalyst is sensitive to ultraviolet (UV) light; this is why its photocatalytic activity and quantum efficiency are reduced. To enhance the photocatalytic efficiency in the visible light range as well as to increase the number of the active sites on the crystal surface or inhibit the recombination rate of photogenerated electron–hole pairs electrons, various metal ions were used to modify TiO₂. This review paper comprehensively summarizes the latest progress on the modification of TiO₂ photocatalyst by a variety of metal ions. Lastly, the future prospects of the modification of TiO₂ as a photocatalyst are proposed.

Give me more fluorines: introduction of fluorine in the structure of Covalent Triazine Frameworks can improve their CO₂adsorption. Materials with optimal fluorine content and narrow nanopore distribution are promising CO₂scavengers.

As the discharge amount of dye wastewater increases with the development of the textile printing and dyeing industries, the treatment of the dyes in the wastewater becomes more complex. The adsorption method is a commonly used method for treating dye wastewater. The adsorbent is the key factor affecting the adsorption performance. To develop a high-performance adsorbent, a porous carbon material prepared from potassium citrate by the calcination method was applied in the adsorption of dye-containing water in this study. The morphology and pore structure of the porous carbon materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and N₂ adsorption/desorption isotherm. The porous carbon material with a specific surface area of 1436 m² g^-1, PC-900, was used as an adsorbent for the adsorption of methyl orange (MO) and methylene blue (MB). The results showed that the maximum adsorption capacity of PC-900 for MO and MB reached 927 and 1853.6 mg g^-1, respectively. Studies on adsorption kinetics and adsorption isotherms showed that the pseudo-second-order kinetic model and the Langmuir isotherm model were more appropriate to describe the adsorption process of MO and MB by PC-900. In addition, the results of the mixed adsorption experiment of MO and MB dyes showed that PC-900 had selective adsorption for MB.