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In this work, a novel p-n heterojunction polyimide aerogel/BiOBr (PI/BOB) photocatalyst was successfully synthesized by combining supercritical drying and in-situ precipitation method, to degrade organic pollutants in visible light. The synthesized PI/BOB photocatalysts exhibited excellent photocatalytic activity by establishing p-n heterojunction with improved charge separation and transfer performance. Moreover, the combination of BiOBr and PI can effectively reduce the hydrophobicity of PI and help to improve its application in water pollution treatment. After a comprehensive study of the microstructure and optical properties of PI/BiOBr heterojunction, it is found that the combination of PI and BiOBr nanosheets can expand the light absorption range, and the porous PI can greatly increase the specific surface area of PI/BiOBr heterojunctions. Furthermore, XPS results showed that the electron in PI transferred to BiOBr through the concentration differences, thus generating an internal electric field (IEF) between PI and BiOBr. Under the effect of IEF, photogenerated carriers can be separated between PI and BiOBr more efficiently, which can effectively improve the photocatalytic efficiency. Photocatalytic degradation experiments showed that PI/BOB has excellent photocatalytic degradation effect on RhB, and the degradation rate of 50 mg RhB was 99% in 60 min for 20 mg catalyst. Charge transfer mechanism in heterojunction under different light conditions [Display omitted] • Successfully prepared porous polyimide aerogel with high specific surface. • Combination of organic and inorganic semiconductors by hydrothermal method. • Construction of p-n type heterojunctions facilitates electron-hole separation. • xPI/BOB has a significantly higher degradation efficiency for RhB. [ABSTRACT FROM AUTHOR]

• The visible light corresponding BiOBr nanosheets were prepared by one-step water bath heating method. • The combination of diatomic doping and nanosheet construction can promote the photocatalytic performance of BiOBr. • The BiOBr nanosheets can rapidly degrade Tetracycline hydrochloride and high concentration RhB. Designing efficient photocatalysts is essential for improving photocatalytic performance. Separation efficiency of photogenerated carriers is one of the key factors affecting photocatalytic performance. Combining the construction of two-dimensional materials with elemental doping can further improve the separation of photogenerated carriers. As expected, the performance of the samples produced by Fe and Cu co-doping was superior to that of pure BiOBr and mono-doped samples, with significant improvements in the photocatalytic degradation of both rhodamine B and tetracycline. The dopant of excess metal element atoms can form impurity energy levels in the forbidden band that effectively facilitate the separation and migration of photogenerated carriers. Meanwhile, the thin-layer two-dimensional structure can effectively shorten the bulk charge carrier transmission distance and improve the transmission efficiency. This study not only provides a simple, green and low-cost method for combining iron and copper into composites materials at same time but also confirmed that the photocatalytic performance of BiOBr was strongly influenced by different Fe and Cu contents. [ABSTRACT FROM AUTHOR]

A visible-light-responsive hybrid photocatalyst, K-doped g-C 3 N 4 /BiOBr, has been synthesized by K-doped g-C 3 N 4 (K–CN) and BiOBr. The property of photocatalysts was characterized by XRD, FT-IR, TEM, SEM, DRS, PL, EIS and HPLC. The photocatalytic activity of K-doped g-C 3 N 4 /BiOBr was evaluated by degradation of Rhodamine B (RhB) and tetracycline hydrochloride under visible-light irradiation. The K-doped g-C 3 N 4 /BiOBr hybrid photocatalyst which contains K–CN with mass fraction of 20% (20K–CN/BiOBr) shows the best degradation efficiency of RhB. The degradation efficiency of RhB (20 mg/L) can be achieved to 99% and the degradation efficiency of tetracycline hydrochloride by BiOBr decreased with the increase of K-doped g-C 3 N 4 doping. The results of photocurrent and EIS assumed that the tight coupling between K–CN and BiOBr can enhance the separating efficiency of photo-generated carrier. In addition, the capture experiment proof that h+ is the primary active substance in the system of reaction and ·OH is the auxiliary active substance. After five degradation experiments, the efficiency of the degradation of Rhodamine B by the sample can still reach 90%, which proves that the samples are stable. A new and efficient method is provided in this work to solve the pollution of organic dyes and antibiotics. [ABSTRACT FROM AUTHOR]

The synergistic effect of sodium and oxygen expands π-conjugated aromatic rings and distortion of the heptazine skeleton, enhancing the intrinsic π→π* electron transition and the effective n→π* electron transition. [Display omitted] • A sodium and oxygen co-doped g-C 3 N 4 (NaOCN) is prepared by facile microwave synthesis, in which Na as a charge transport channel promotes the separation efficiency of photogenerated carriers. • The as-prepared NaOCN exhibits the NIR absorption extended to 1400 nm and the apparent quantum yield (AQY) can keep 26.9% at 420 nm and still maintain 7.2 % at 600 nm, which shows strong NIR response range. • The intrinsic π → π* electron transition and active the n → π* electron transition generated by the synergistic effect of Na and O atoms are the main factor to promote the NIR response of NaOCN. Efficient utilization of near-infrared light (NIR) is critical to optimize the performance of photocatalysts. Herein, an ultrafast process is employed to co-condensation of melamine and NaCl by microwave-assist heating. The fabricated sodium and oxygen co-doped g-C 3 N 4 (NaOCN) shows extended π-conjugated aromatic rings and distortion of the heptazine skeleton, which can enhance the intrinsic π → π* electron transition and active the n → π* electron transition. The robust n → π* excitation of NaOCN leads to a narrowed bandgap of 2.73 eV with the NIR absorption extending to 1400 nm. The apparent quantum yield (AQY) for NaOCN can still keep 7.2 % at 600 nm. This work provides a promising way for the application of NIR-based carbon nitride in photocatalytic H 2 O 2 production. [ABSTRACT FROM AUTHOR]

MoS 2 /TiO 2 based nanocomposites exhibit great prospect in the area of photocatalysis and rechargeable batteries. However, many efforts have to be made to avoid the agglomeration of MoS 2 on TiO 2 nanobelts, to increase the interfacial bonding between MoS 2 and TiO 2 , and to utilize the inert basal surface of 2H–MoS 2. Herein, we report the TiO 2 /Ag/MoS 2 /Ag nanocomposites with double Ag loadings by hydrothermal method combined with the Tollen reaction. The as-obtained nanocomposites possess excellent photocatalytic performance to Cr (Ⅵ) and RhB, which is ascribed to the fast transfer and effective separation of charge carriers due to the formation of heterojunction between TiO 2 /Ag/MoS 2 and MoS 2 /Ag. The present study illustrates the potential application of these analogous multiphase nanocomposites for water purification. [ABSTRACT FROM AUTHOR]

Bi 4 O 5 I 2 /Bi 2 O 2 CO 3 p-n heterojunction photocatalysts were synthesized by utilizing different ratios of solvent via a one-pot solvothermal method in the process of synthesizing Bi 4 O 5 I 2 and Bi 5 O 7 I. The structure, morphology and photoelectric properties of the prepared samples were characterized by XRD, SEM, TEM, FTIR, XPS and DRS. Through the estimated photocatalytic degradation of pollutants such as tetracycline hydrochloride (TC) and rhodamine B (RhB), it was found that the Bi 4 O 5 I 2 /Bi 2 O 2 CO 3 (the ratio of ethylene glycol and distilled water in the solvent was 3/5) heterojunction photocatalyst had the highest degradation, with the removal of up to 80.6% from all prepared samples within 30 min under visible light irradiation; this heterojunction also showed better RhB degradation performance. The presence of an internal electrostatic field between the p-type semiconductor Bi 4 O 5 I 2 and n-type semiconductor Bi 2 O 2 CO 3 effectively suppressed the recombination of photoinduced electron–hole pairs. Moreover, a feasible mechanism was proposed. [ABSTRACT FROM AUTHOR]

In this work, Bi 4 O 5 I 2 -Bi 2 O 2 CO 3 -BiOCl 0.8 I 0.2 n-p-n heterojunction was synthesized by in-situ growth method. Different types of BiOX (X = Br, Cl and I) materials were combined to optimize the charge separation of prepared heterogeneous junction so as to improve the photocatalytic performance. It had been proved by various characterization methods that the charge carrier recombination would be greatly suppressed under the action of internal electric field at the interface when n-p-n heterojunction was formed. Specially, 20-Bi 4 O 5 I 2 -Bi 2 O 2 CO 3 -BiOCl 0.8 I 0.2 presented the best photocatalytic performance, which could degrade 99% of Rhodamine B (RhB) in 60 min under 500 W Xe lamp source. BiOCl 0.8 I 0.2 improves the performance of photocatalytic and broaden the light absorption range of pure BiOI. This work provides a new perspective to design ternary structures that enhance photocatalytic performance. [Display omitted] [ABSTRACT FROM AUTHOR]

• A photocatalyst was constructed by combining direct Z-scheme and isotype heterojunction. • A ternary Δ(Z + H)-scheme g-C 3 N 4 /g-C 3 N 4 /BiOBr photocatalyst is prepared by an effective combination of thermal decomposition and solvothermal method. • Solar light utilization can be enhanced in ternary Δ(Z + H)-scheme g-C 3 N 4 /g-C 3 N 4 /BiOBr. • The composites is wide application in the degradation of organic pollutants (RhB, FITC and TC), which potential to be applied as a photocatalyst for wastewater treatment. A novel ternary direct Z-scheme + isotype heterojunction, Δ(Z + H)-scheme photocatalyst CN-TU/BiOBr was fabricated by an effective combination of thermal decomposition and solvothermal method. The samples of g-C 3 N 4 prepared using urea, thiourea and thiourea-urea complexes as precursors were named CN-U, CN-T and CN-TU, respectively. In addition, CN-M was prepared by physically mixing CN-U and CN-T. The structure, morphology, optical and electronic properties of the prepared samples were characterized by XRD, FTIR spectra, SEM-EDS, BET, XPS and DRS. The photocatalytic activities of the synthesized samples were estimated by the degradation of Rhodamine B (RhB), Fluorescein isothiocyanate (FITC) and antibiotic tetracycline hydrochloride (TC) in the presence of visible light. Compared with other as-prepared samples, the ternary 1%CN-TU/BiOBr photocatalyst exhibited an excellent activity, which is attributed to the construction of the ternary Δ(Z + H)-scheme not only benefit to maintain outstanding redox capability of the electrons, but also facilitates the separation of photo-generated carrier. Furthermore, the stability of the sample is tested by cyclic experiments. This work will provided a new insight into optimizing the structure and designing similar Z-scheme photocatalytic system. [ABSTRACT FROM AUTHOR]