Enhanced visible light photocatalytic performance of carbon and oxygen co-doped carbon nitride with a three-dimensional structure: Performance and mechanism study.

As a cost-effective photocatalyst, carbon nitride (g-C3N4) holds tremendous promise for addressing energy shortages and environmental pollution. However, its application is limited by disadvantages such as low specific surface area and easy recombination of photogenerated electron-hole pairs. This study introduces C and O co-doped g-C3N4 with a three-dimensional (3D) structure achieved through a straightforward one-step calcination process, demonstrating excellent photocatalytic activity of hydrogen production and oxytetracycline degradation, with superoxide radicals as the primary active species. We propose a plausible enhanced mechanism based on systematic characterizations and density functional theory calculations. The 3D structure confers a substantial specific surface area, enhancing both the adsorption area and active sites of catalysts while bolstering structural stability. Co-doping optimizes the band structure and electric conductivity of the catalyst, facilitating rapid migration of photogenerated charges. The synergistic effects of these enhancements significantly elevate the photocatalytic performance. This study presents a convenient and feasible method for the preparation of dual-regulated photocatalysts with outstanding performance.

Facile fabrication of 3D hollow porous aminopyridine rings decorated polymeric carbon nitride for enhanced photocatalytic hydrogen evolution and dye elimination.

In consideration of energy shortages and environmental pollution, there is a critical need to develop a photocatalyst with high catalytic performance for rapid hydrogen production and efficient pollutant degradation. We synthesized a photocatalytic composite catalyst with three-dimensional (3D) porous aminopyridine rings grafted on the edge of g-C3N4 (APCN) using melamine, cyanuric acid and 4-aminopyridine as raw materials. The composite catalyst exhibited excellent photocatalytic performance for H2 production (2.44 mmol g-1h-1) and RhB degradation (97.08%) under visible light. Subsequently, a possible enhanced mechanism of the catalyst was proposed on the basis of a series of characterization and photocatalytic experiments. The 3D porous structure not only enhanced the structural stability but also increased the surface area of the APCN catalysts, which generated more exposed active sites. Moreover, the aminopyridine ring embellishment was beneficial for achieving a narrowed bandgap and charge migration and separation, which decreased the occurrence of photogenerated carrier recombination. In summary, these two structural features showed a synergistic effect to enhance the photocatalytic performance of the APCN catalyst. Finally, an integrated feasible enhanced mechanism of photocatalytic activity was elucidated according to the results of active substance capture tests, showing that O2•- played an important role during RhB degradation.

Efficient Dye Contaminant Elimination and Simultaneously Electricity Production via a Bi-Doped TiO2 Photocatalytic Fuel Cell.

TiO2 develops a higher efficiency when doping Bi into it by increasing the visible light absorption and inhibiting the recombination of photogenerated charges. Herein, a highly efficient Bi doped TiO2 photoanode was fabricated via a one-step modified sol-gel method and a screen-printing technique for the anode of photocatalytic fuel cell (PFC). A maximum degradation rate of 91.2% of Rhodamine B (RhB) and of 89% after being repeated 5 times with only 2% lost reflected an enhanced PFC performance and demonstrated an excellent stability under visible-light irradiation. The excellent degradation performance was attributed to the enhanced visible-light response and decreased electron-hole recombination rate. Meanwhile, an excellent linear correlation was observed between the efficient photocurrent of PFC and the chemical oxygen demand of solution when RhB is sufficient.