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The application of advanced oxidation processes in wastewater treatment has attracted wide attention, in the past year. With excellent photoelectric properties and catalytic stability, graphitic carbon nitride and its derivatives have high catalytic performance. Compared to traditional g-C 3 N 4 materials, g-C 3 N 5 has a narrower band gap (g-C 3 N 5 has a band gap of about 2.0 eV and g-C 3 N 4 has a band gap of about 2.6 eV) and better electron excitation distribution due to it has a higher proportion of N atoms. In this study, the composites of Co atom doped g-C 3 N 5 were synthesized and characterized. Co atoms are successfully doped into g-C 3 N 5 , which is proved by TEM, XPS and XRD experimental results. PMS can be activated by Co-C 3 N 5 , and RhB degradation efficiency is as high as 95.8 % within 40 min. The experimental results show that the doping of metal Co can effectively improve the catalytic performance of carbon nitride materials. The degradation efficiency of RHB activated by C 3 N 5 , C 3 N 4 and Co-C 3 N 4 was 18.2 %, 11.2 % and 41.8 %, respectively, while the degradation efficiency of Co-C 3 N 5 was as high as 95.8 %. RhB was effectively degraded over a wide pH range (3.0–10.9) and under various anion conditions, indicating the excellent environmental suitability of Co-C 3 N 5. The results of free radical quenching experiments and EPR tests showed that the contribution of active species to RhB degradation was as follows: SO 4 •− >1O 2 > O 2 •−. This paper provides a new perspective using Co-C 3 N 5 as a catalyst for PMS-based Fenton reaction. [Display omitted] [ABSTRACT FROM AUTHOR]

By taking advantage of in-situ generated H 2 O 2 , Z-scheme Fe 2 (MoO 4) 3 /Ag/Ag 3 PO 4 heterojunction displayed outstanding degradation performance. [Display omitted] • Internal-electric-field is built at interface, resulting in a Z-scheme routine of e - • k of Fe 2 (MoO 4) 3 /Ag/Ag 3 PO 4 is 254 and 7.0 times than those of Fe 2 (MoO 4) 3 and Ag 3 PO 4. • H 2 O 2 is activated on Fe 2 (MoO 4) 3 for •OH, avoiding quenching effect on h + and e - • k is improved by 1.7 times via turning waste (H 2 O 2) into wealth (•OH) • 91.2% of removal efficiency is remained after 5 runs, while that of Ag 3 PO 4 is 68.1% Ag 3 PO 4 -based photocatalysts have been deeply studied in environmental remediation; however, two problems limited their further application: photocorrosion and quenching effect by in-situ generated H 2 O 2. To addressed these two questions simultaneously, Fe 2 (MoO 4) 3 was coupled with Ag 3 PO 4 to construct Z-scheme Fe 2 (MoO 4) 3 /Ag/Ag 3 PO 4 heterojunction driven by internal-electric-field. The rhodamine B degradation rate of heterojunction was 254 and 7.0 times higher than those of Fe 2 (MoO 4) 3 and Ag 3 PO 4 , respectively. The outstanding photoactivity was due to the high visible-light harvest, low interface resistance, high separation efficiency of charge carriers, long lifetime of hole (h +) and electron (e -), well-preserved oxidation potential of h +, and especially photocatalytic produced H 2 O 2 inside the system. The in-situ generated H 2 O 2 was fully activated to be •OH on the Fe 2 (MoO 4) 3 surface via a Fenton reaction, leading to the elimination of quenching effect on h + and e -, and generation of more •OH. Additionally, in Z-scheme heterojunction, e - transferred from Ag 3 PO 4 to Fe 2 (MoO 4) 3 , avoiding the accumulation on Ag 3 PO 4 surface, and hence suppressing the photocorrosion. As a result, 91.2% of degradation efficiency remained after 5 cycles. This paper provides a new method to simultaneously increase the degradation rate by utilizing the in-situ generated H 2 O 2 and improve the stability of Ag 3 PO 4 via constructing a Z-scheme heterojunction. [ABSTRACT FROM AUTHOR]

Nowadays, non-typical yolk/shell structure has drawn much attentions due to the better catalytic performance than traditional counterparts (one yolk/one shell). In this study, ZIF-67 @Co 2 SiO 4 /SiO 2 yolk/shell structure was prepared in one-step at room temperature, in which ZIF-67 was served as the hard-template, H 2 O was served as etchant and tetraethyl orthosilicat was served as the raw material for Co 2 SiO 4 /SiO 2. After calcination, the non-typical Co x O y @Co 2 SiO 4 /SiO 2 yolk/shell nanoreactor with Co 2 SiO 4 /SiO 2 dual-shells and Co x O y multiple-cores was obtained. On the one hand, more active sites were exposed on multiple-cores surface and better protection were provided by dual-shells. On the other hand, the sheet-like Co 2 SiO 4 inner shell not only extended the travel path and retention time of pollutants trapped in cavity, but also separated the multiple-cores from aggregation. Therefore, the nanoreactor displayed the outstanding catalytic activity and recyclability in Fenton-like reaction. Metronidazole (20 mg/L) was completely degraded after 30 min, rhodamine B (50 mg/L) and methyl orange (20 mg/L) were removed even within 5.0 min. Catalytic mechanism indicated that 1O 2 greatly contributed to the pollutant degradation. This paper presented a simple, versatile, green and energy-saving method for non-typical yolk/shell nanoreactor, and it could inspire to prepare other catalysts with high activity and stability for environmental remediation. [Display omitted] • Yolk/shell nanoreactor with dual-shells and multiple-cores is prepared in two-steps. • Formation mechanism is clearly revealed and the recipe is versatile to MOF template. • Various pollutants are rapidly degraded due to more active sites on multiple-cores. • Confine effect inside of the nanoreactor is identified via tracing the 1O 2 source. • Leached Co2+ is 75 times lower than Co x O y due to better protection from dual-shells. [ABSTRACT FROM AUTHOR]

Fe 3 O 4 @PB core/shell composites were prepared by a reactive-template method. They served as effective catalyst in photo-Fenton reaction toward rhodamine B degradation. • Photo-Fenton reaction was performed on the surfaces of both Fe 3 O 4 core and PB shell • k of Fe 3 O 4 @PB composite was 7.44 × 10−3 min-1, 1.5 times higher than that of Fe 3 O 4 NC • E a of Fe 3 O 4 @PB composite was 15.1 kJ/mol, 1.2 times lower than that of Fe 3 O 4 NC • △ H , △ S and △ G was 15.0 kJ/mol, 31.3 J/mol K and 5.56 kJ/mol • 97.6 % of degradation efficiency was remained after the 5th cycle In this study, Fe 3 O 4 @Prussian blue (PB) core/shell composite was prepared via a reactive-template method. The morphological and structural characteristics of composite were carefully investigated by X-ray diffraction, transmission electron microscope, scanning electron microscope, Fourier transform infrared spectrometer and and X-ray photoelectron spectroscope. Their activity in photo-Fenton reaction was examined using rhodamine B (RhB) degradation as a model reaction, and the optimal degradation condition was determined to be 10 mg/L of RhB, 587 mM of H 2 O 2 , pH = 6.5 and 318 K. Rate constant of the reaction catalyzed by Fe 3 O 4 @PB composites was 7.44 × 10−3 min-1, about 1.5 times higher than that catalyzed by Fe 3 O 4 nanoclusters (NCs). The activation energy of the reaction catalyzed by Fe 3 O 4 @PB composites was 1.2 times lower than that catalyzed by Fe 3 O 4 NCs. Mechanism study indicated that OH played a dominating role in RhB degradation. In addition, Fe 3 O 4 @PB core/shell composites with a saturation magnetization of 33.4 emu/g were easily recycled via a magnet. Almost 97.6 % of degradation efficiency was remained after the 5thcycle, indicating their good reusability. This study suggested that Fe 3 O 4 @PB core/shell composite demonstrated a potential application for the removal of persistent organics from aquatic environments. [ABSTRACT FROM AUTHOR]

Phosphorus-doped carbon nitride/phosphorus and sulphur co -doped carbon nitride isotype heterojunction was prepared by a two-step calcination method. They displayed high photoactivity and reusability toward the rhodamine B degradation. Photocatalysis was one of the most promising techniques for environmental remediation. Exploring photocatalysts with high efficiency, low cost and easy preparation was still an ongoing issue. In this work, phosphorus-doped carbon nitride/phosphorus and sulfur co -doped carbon nitride (P-C 3 N 4 /PS-C 3 N 4) isotype heterojunction was prepared by a two-step calcination method. The composite displayed a sheet-like structure with a surface area of 23 m2/g. Compared with pure C 3 N 4 , band gaps of P-C 3 N 4 and PS-C 3 N 4 were only slightly modified during the heteroatom-doping process. Therefore, a well-matched band alignment was constructed, which not only improved the separation efficiency of photogenerated electron-hole pairs, but also well preserved the high oxidizability of holes on valance band and good reducibility of electrons on conduction band. Because of the similarity in physicochemical properties, the interface resistance between P-C 3 N 4 and PS-C 3 N 4 was low, which accelerated the electron transfer and prolonged the lifetime of charge carriers. Although the visible-light utilization was somewhat low in comparison with P-C 3 N 4 and PS-C 3 N 4 , by taking advantage of above merits, P-C 3 N 4 /PS-C 3 N 4 displayed the high photocatalytic activity in rhodamine B degradation, and the reaction rate constant was 0.183 min−1, about 8.7 and 4.0 times higher than those of P-C 3 N 4 and PS-C 3 N 4. Besides high catalytic activity, isotype heterojunction displayed good recyclability, since 95.3% of catalytic activity was maintained after the 5th cycle. The method presented here was facile, economic and environmentally benign, thus it was highly attractive for the application in environmental remediation. [ABSTRACT FROM AUTHOR]