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Graphitic carbon nitride (g-C 3 N 4) faces limitations in photocatalytic application due to its limited light response and high recombination rate of photo-generated charge carriers. Herein, we synthesized a K, P co-doped g-C 3 N 4 (KPCN) with cyano defects via microwave-assisted heating of the mixture of KH 2 PO 4 and melamine in just 7 min. The KPCN exhibits a reduced bandgap of 2.37 eV and introduces a mid-gap of 1.77 eV, which broadens light absorption to the visible-near-infrared (vis-NIR) spectrum with light absorption to 867 nm. Impressively, the co-doped K and P adjust the interlayer and in-plane electron distribution of g-C 3 N 4 , enhancing charge separation and transfer. The KPCN exhibits a remarkable improvement in H 2 O 2 yield of 7.74 mM g−1 h−1, demonstrating superior catalytic activity compared to microwave pure g-C 3 N 4 (MCN, 5.1 times) and bulk g-C 3 N 4 (BCN, 19.2 times). The results indicate that the K, P co-doped g-C 3 N 4 synthesized rapidly and efficiently by microwave method has relatively stable and considerable photocatalytic activity, which has great potential application in the industrial production of H 2 O 2. • K, P co-doped g-C 3 N 4 (KPCN) was prepared by rapid microwave synthesis in just 7 min. • K, P co-doping optimizes the in-plane electron distribution and interlayer electron migration of g-C 3 N 4. • KPCN exhibits a reduced bandgap from 2.75 eV to 2.37 eV and introduces a mid-gap at 1.77 eV. [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]

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]