Microwave solvothermal-assisted calcined synthesis of Bi2WxMo1−XO6 solid solution photocatalysts for degradation and detoxification of bisphenol A under simulated sunlight irradiation

Boosting photocatalytic performance of polymeric carbon nitride by adjusting its donor-acceptor structure via functional group modification strategy

Solar-driven photodegradation of pollutant is attractive for environmental remediation. Herein, we designed and synthetized a new kind of group-modified polymeric carbon nitride (PCN) photocatalyst with urea and 4-Nitro-o-phenylenediamine by one-pot method and applied to degrade bisphenol A (BPA) in aqueous solution. The light response range of photocatalyst had been extended a lot due to conjugation and electron-withdrawing properties of nitrobenzene. Physical analysis shows that 4-Nitro-o-phenylenediamine grafting brings an improved charge separation capacity. EPR and DFT results demonstrate the charge separation is significantly affected by the donor-acceptor structure of PCN, which can be altered via aromatic electron-withdrawing group. The kinetic constant of photocatalytic degradation for BPA was promoted by 8.8-times greater than unmodified PCN and a good recyclability was achieved. To verify the universality of group modification strategies, we prepared other two kinds of photocatalysts via electron-withdrawing group modification strategy and their photocatalytic performance all had been improved obviously.

Enhancement of Charge Separation and NIR Light Harvesting through Construction of 2D-2D Bi4 O5 I2 /BiOBr:Yb3+ , Er3+ Z-Scheme Heterojunctions for Improved Full-Spectrum Photocatalytic Performance

Developing full-spectrum photocatalysts with simultaneous broadband light absorption, excellent charge separation, and high redox capabilities is becoming increasingly significant. Herein, inspired by the similarities in crystalline structures and compositions, a unique 2D-2D Bi₄ O₅ I₂ /BiOBr:Yb³⁺ ,Er³⁺ (BI-BYE) Z-scheme heterojunction with upconversion (UC) functionality is successfully designed and fabricated. The co-doped Yb³⁺ and Er³⁺ harvest near-infrared (NIR) light and then convert it into visible light via the UC function, expanding the optical response range of the photocatalytic system. The intimate 2D-2D interface contact provides more charge migration channels and enhances the Förster resonant energy transfer of BI-BYE, leading to significantly improved NIR light utilization efficiency. Density functional theory (DFT) calculations and experimental results confirm that the Z-scheme heterojunction is formed and that this heterojunction endows the BI-BYE heterostructure with high charge separation and strong redox capability. Benefit from these synergies, the optimized 75BI-25BYE heterostructure exhibits the highest photocatalytic performance for Bisphenol A (BPA) degradation under full-spectrum and NIR light irradiation, outperforming BYE by 6.0 and 5.3 times, respectively. This work paves an effective approach for designing highly efficient full-spectrum responsive Z-scheme heterojunction photocatalysts with UC function.

Ultrahigh-efficient BiOBr-x%La@y%CNQDs nanocomposites with enhanced generation and separation of photogenerated carriers towards bisphenol A degradation and toxicity reduction

In this study, a series of hierarchical flower-like La-doped BiOBr composites modified with carbon nitride quantum dots (BiOBr-x%La@y%CNQDs) was synthesized using a microwave solvothermal method in combination with a calcination method. It was found that La doping and CNQDs co-decorated with BiOBr showed much better photoreactivity for bisphenol A (BPA) degradation than pure BiOBr. The best degradation and mineralization efficiencies of BPA were 100% and 77% within 12 min at La and CNQDs contents of 1% and 1.25%, respectively. Various characterization results demonstrated that this synergistic effect on BiOBr-1%La@1.25%CNQDs was attributed to its improved light-harvesting properties, enhanced photogenerated electron and holes pairs separation and interfacial charge transfer. Degradation pathways were proposed based on active species analysis, identification of nine intermediates, and density functional theory (DFT) calculations. Furthermore, a bioluminescence assay of the inhibition rate of the luminescent bacterium Vibrio qinghaiensis sp. Q67 showed that BiOBr-1%La@1.25%CNQDs have superior detoxification ability. The present study provides some insight into the design of ultrahigh-efficiency nanojunction photocatalysts with a broadened photoabsorption range and improved separation efficiency of photogenerated carriers to enhance the degradation and detoxification performance of BPA.

Porous Oxygen-Doped g-C3N4 with the Different Precursors for Excellent Photocatalytic Activities under Visible Light

Antibiotic contamination has received widespread attention globally. In this work, the oxygen-doped porous graphite carbonitride (g-C₃N₄) was prepared with urea and ammonium oxalate (CNUC) or urea and glycine (CNUG) as precursors by thermal polymerization. Using bisphenol A (BPA) as a probe and CNUC or CNUG as photocatalysts, the removal performance test was carried out. Meanwhile, all prepared photocatalysts were characterized by XRD, FT-IR, SEM, TEM, XPS, UV-Vis DRS, PL and EIS. Under visible light irradiation, both CNUC and CNUG exhibited about seven and five times greater photocatalytic activity than that of pure g-C₃N₄, respectively. The radical capture experiments verified that superoxide radicals (•O₂⁻) and holes (h⁺) were the main active species in the photocatalytic degradation of BPA by CNUC, and the possible photocatalytic mechanism of CNUC was proposed. In addition, all these results indicate that CNUC catalyst can effectually inhibit the photocorrosion and keep superior stability. The proposed technique provides a prospective approach to develop nonmetal-modified photocatalysts for future applications.