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Metal-free porphyrin with good planarity is beneficial to π–π stack interactions, which promotes electron coupling and the separation and transfer of photogenerated carriers. It is necessary to develop metal-free porphyrin-based photocatalysts and exploit the photocatalytic mechanism. Herein, metal–free porphyrin (5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, TCPP) was self-assembled through an acid-based neutralization reaction and mixing dual-solvents under surfactants to form different aggregates. Morphology structures, optical and optoelectronic properties of the TCPP aggregates were characterized in detail. TCPP self-assemblies showed higher photocatalytic activities for the degradation of phenol under visible light than untreated TCPP powders, and the aggregates of nanorods formed through the acid-based neutralization reaction in the presence of hexadecyl trimethyl ammonium bromide (CTAB) possessed 2.6 times more activity than the nanofiber aggregates formed through mixing dual-solvents. It was proved that self-assembly methods are crucial for controlling the aggregation of porphyrins to form different aggregations, which have a profound impact on the photocatalytic activity. [ABSTRACT FROM AUTHOR]

Three-dimensional PANI/CdSNRs-SiO2 hydrogel (CdS NRs-PANI-SiO2) was synthesized by loading polyaniline (PANI) onto the semiconductor CdS nanorods (NRs) surface and loading the binary complex on SiO2 gel. The structure, optical properties, and electrochemical properties of the composite were studied in detail. The hydrogen production amount of CdS NRs-PANI (3%)-SiO2 (20%) increased in comparison with CdS NRs and reached 43.25 mmol/g in 3 h under visible light. The three-dimensional structure of SiO2 hydrogel increased the specific surface area of the catalyst, which was conducive to exposing more active sites of the catalyst. In addition, the conductive polymer PANI coated on CdS NRs played the role of conductive charge and effectively inhibited the photo-corrosion of CdS NRs. In addition, the recovery experiment showed that the recovery rate of the composite catalyst reached 90% and hydrogen production efficiency remained unchanged after five cycles, indicating that the composite catalyst had excellent stability. [ABSTRACT FROM AUTHOR]

This paper reports that hybrid titanium dioxide (TiO 2 ) packaged self-assembly perylenetetracarboxylic acid diimide (PTCDI) by self-assembly. These were synthesized through simple mechanical milling that has great photocatalytic performance under visible light. The PTCDI@TiO 2 composite had high activity for the degradation of phenol and 2,4-dichlorophenol, which were 2.3 and 3.2 times of the monomer PTCDI, respectively. After three cycles, the activity of the composite catalyst remained at 70%. Further analysis showed that the photocatalytic activity and stability are mainly due to the enhancement of the charge mobility by the π-π conjugated structure in PTCDI. Moreover, the good energy level matching between PTCDI and TiO 2 helps to separate the electron-hole, thus improving the photocatalytic performance of the composite. The origin of photocatalytic activity was greatly improved due to holes and O 2 − , which was mainly attributed to the strong interaction between PTCDI and TiO 2 . [ABSTRACT FROM AUTHOR]

Ag 3 PO 4 @g-C 3 N 4 core@shell composites were prepared via an ultrasonication/chemisorption method. The degradation of methylene blue (MB) over Ag 3 PO 4 @g-C 3 N 4 composites was investigated to evaluate their photocatalytic performance. The Ag 3 PO 4 @g-C 3 N 4 sample presented the best photocatalytic activity, degrading 97% MB after irradiation for 30 min. Superior stability was also observed in the cyclic runs. The composite has excellent photocatalytic activity and photo-stability and the optimal content of g-C 3 N 4 in the composites is 7.0 wt.%. The efficient photo-generated charge separation originated from a strong interaction in the intimately contact interface, which was confirmed by the results of photocurrent and EIS measurements. Based on the experimental results, a photocatalytic mechanism for organics degradation over Ag 3 PO 4 @g-C 3 N 4 photocatalysts was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Cu/CuFe 2 O 4 -OVs photocatalyst with a two-electron centre was prepared. • Cu/CuFe 2 O 4 -OVs and H 2 O 2 formed a photocatalysis-Fenton synergy system. • The synergy system showed efficient degradation activity of organic pollutants. • Cu0 acts as an electronic transfer channel of Fe, Cu and the two-electron centre. • OVs activate H 2 O 2 and promote the separation of photogenerated carriers. To promote the separation of photogenerated carriers, break through the bottleneck of classical Fenton reaction, and achieve the efficient degradation of organic pollutants, a two-electron centre Cu/CuFe 2 O 4 with oxygen vacancies (Cu/CuFe 2 O 4 -OVs) 1 1 Cu/CuFe 2 O 4 with oxygen vacancies, Cu/CuFe 2 O 4 -OVs. was synthesised by citric acid complexation and ascorbic acid (Vc) 2 2 ascorbic acid, Vc. in-situ reduction. Under visible light irradiation, H 2 O 2 was added to form a two-electron centre synergistic photocatalysis-Fenton degradation system that could degrade 100 ppm of phenol by 92.72% in 18 min. The degradation efficiency constant was 8165 and 4.35 times that of photocatalysis and Fenton oxidation, respectively. Such excellent degradation activity is attributed to the synergistic effect of the two-electron centre and photocatalysis-Fenton. Cu0 has two functions: (1) it acts as an electronic bridge of Fe and Cu in Fenton and accelerates the separation of photogenerated carriers; (2) it acts as the transfer channel of the two-electron centre. Oxygen vacancies are electron-rich centres that activate H 2 O 2 , while the electron-poor centre Cu(II) captures photogenerated electrons and phenol electrons. Quenching experiments and EPR results indicated that OH, O 2 − and h+ are the main active species. The synergistic degradation mechanism was proposed based on experiments and theoretical calculations. Through further optimization of the conditions and cyclic regeneration stability test, the system was extended to degrade different dyes, phenolic organic pollutants and coking wastewater. [ABSTRACT FROM AUTHOR]

Highlights • A core-shell structure photocatalysts of Ag 3 PO 4 @P3HT was prepared successfully. • P3HT greatly increased visible light response for Ag 3 PO 4. • The close contact makes the conjugated π bond system of P3HT interact with Ag 3 PO 4. • The photocatalysts exhibited higher activity for the degradation organic pollutant. Abstract The composite photocatalyst Ag 3 PO 4 @P3HT with core-shell structure was synthesized through a simple method, and SEM, TEM and FTIR were used to detect the presence of P3HT in the composite catalyst and to confirm its structure. The sample's photodegradation ability was studied by degradation the organic pollutants phenol and BPA under visible light irradiation. Through experimental tests the photocatalytic activity was the highest at 0.07 wt% P3HT, and the degradation of phenol increased by about 23% compared to Ag 3 PO 4. At the same time, and with the same concentration of BPA, the degradation increased by about 25% in 6 min. Photoelectricity, UV–vis spectroscopy, and PL testing were used to study the electrochemical and optical properties of the catalysts. It is concluded that the increase in photocatalytic activity is due to the enhancement of visible light absorption, the more efficient separation of photogenerated e−/h+, and the faster transfer of photogenerated carriers. Finally, the mechanism of enhanced photocatalytic activity was discussed in terms of band position. [ABSTRACT FROM AUTHOR]