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Hollow mesoporous polypyrrole (PPy)@Pd‐Fe3O4 nanotubes were prepared using MoO3 nanorods as hard templates in one step, in which construction of PPy nanotubes, preparation of Pd nanoparticles, synthesis of Fe3O4 nanoparticles and removal of MoO3 nanorods were combined together. To the best of our knowledge, this is the simplest approach for the synthesis of nanomaterials with catalytic activity, magnetic property and hollow mesoporous structure simultaneously. Although the preparation procedure was simplified, the catalytic activity and magnetic property were not sacrificed. In the catalytic reduction of 4‐nitrophenol, both reaction rate constant and turnover frequency were higher than those of previous reports. Importantly, the nanotubes could be easily separated from the reaction solution in the presence of a magnetic field, and saturation magnetization could be controlled by the amount of pyrrole monomer. After six recycles, the catalytic activity maintained 94.8% of that of the first run, indicating good stability and reusability. [ABSTRACT FROM AUTHOR]

A Mott-Schottky heterojunction is reported to boost the peroxymonosulfate (PMS) activation in Fenton-like reaction through a non-radical path. The heterojunction with Co nanoparticles encapsulated by nitrogen-doped graphitized carbon (N-GC) shell was synthesized via pyrolysis of ZIF67 @ZIF8 and subsequent acidic treatment. Benefiting from Mott-Schottky effect, the electrons were transferred from Co nanoparticles to the N-GC shell, leading to the rearranged electron density on N-GC surface and improvement of the PMS activation. The PMS activation efficiency of heterojunction (86.0%) was much higher than the reference catalyst without Mott-Schottky effect (35.3%), and even comparable to Co2+ (86.2%). 85.0% of tetracycline (TC) removal efficiency was realized after only 10.0 s. Moreover, the intrinsic advantages of non-radical path were well inherited by Mott-Schottky heterojunction, including high anti-interfere property toward various anions, cations and organics, high catalytic activity in a wide pH range, low metal leaching, and high magnetic recyclability. [Display omitted] • Electrons flow from Co NPs to N-GC and arranged in Mott-Schottky heterojunction. • PMS activation efficiency is comparable to Co2+ and 85.0% of TC is removed at 10 s. • Electrons play crucial role among ROSs, and PMS activation follows non-radical path. • Mechanism of Mott-Schottky effect on enhanced degradation performance is revealed. • EP-ZIF67 @ZIF8 is high environmental adaption, wide applicable pH, low leaching. [ABSTRACT FROM AUTHOR]

Fe-C 3 N 4 /Ti 3 C 2 /C-TiO 2 Z-scheme heterojunction was prepared via coupling Fe-C 3 N 4 and partially oxidized MXenes-derived C-TiO 2 /Ti 3 C 2. It presented excellent catalytic activity and photothermal performance in photo-Fenton reaction toward tetracycline degradation. [Display omitted] Photo-Fenton reaction combining the photocatalytic reaction and Fenton reaction showed excellent degradation performance. However, it highly demanded the catalysts to display outstanding activity in these two reactions. Herein, Fe-doped carbon nitride/MXenes-derived C-TiO 2 /Ti 3 C 2 (Fe-C 3 N 4 /Ti 3 C 2 /C-TiO 2) was prepared via two steps: Fe-C 3 N 4 and Ti 3 C 2 were assembled via face-to-face attachment, following by in-situ partial oxidation of Ti 3 C 2 to C-TiO 2. DFT predicted a Z-scheme charge transfer routine via metallic Ti 3 C 2 as bridge, which was verified by EPR and radical trapping experiments. Additionally, PDOS calculation revealed the charge density around the doped-Fe atoms was remarkably increased, leading to better H 2 O 2 activation, which was experimentally confirmed by high yield of •OH. Moreover, Fe-C 3 N 4 /Ti 3 C 2 /C-TiO 2 possessed the high photothermal effect to accelerate the surface reaction. By taking advantage of these merits, the degradation rate of Fe-C 3 N 4 /Ti 3 C 2 /C-TiO 2 was at least 4.2 times higher than the reference catalysts. Our work provided an insight toward the g -C 3 N 4 /TiO 2 -based photo-Fenton catalysts with high performance. [ABSTRACT FROM AUTHOR]

"Double-yolk egg-like" Fe 3 O 4 /PBA@PPy nanoreactor is synthesized, where the confinement effect from the cavity, the protective effect from the PPy shell, and the magnetic property were successful integrated together. Therefore, it displayed the high degradation efficiency, low leaching, and rapid separation in Fenton-like reaction. [Display omitted] • k of Fe 3 O 4 /PBA@PPy-10 was 0.38 L·min·mol−1, 5.1 times than that of reference Fe 3 O 4 /PBA-10 in Fenton-like reaction. • The concentration of leached cobalt ions was reduced from 1.47 mg/L to 0.174 mg/L by the protective function from the PPy shell. • 84.5% of the degradation efficiency of the 1st cycle was still maintained after 4 cycles. • The core of Fe 3 O 4 make sure the catalyst can be rapidly separated by a magnet. • Mechanism of Fenton-like reaction is revealed in detail. Peroxymonosulfate (PMS)-based Fenton-like reaction is an effective technique for the pollutant degradation, and the Co-based metal organic frameworks displayed the excellent activity for the PMS activation. Nevertheless, how to further improve the catalytic activity, suppress the leaching of toxic cobalt ions, and realize the rapid separation were still challenges for practical application. In this work, a novel solution was proposed: encapsulating Fe 3 O 4 and Prussian blue analogue (PBA) into the polypyrrole (PPy) shell and constructing a "double-yolk egg-like" Fe 3 O 4 /PBA@PPy as a nanoreactor. In Fe 3 O 4 /PBA@PPy-10, the catalytic performance was remarkably enhanced with the help of confinement effect, and the degradation rate (0.38 L·min·mol−1) was 5.1 times than that of reference Fe 3 O 4 /PBA-10 (0.074 L·min·mol−1). In addition, the concentration of leached cobalt ions was reduced to only 0.174 mg/L by the protective function from the PPy shell. Moreover, the nanoreactor could be magnetically separated from the reaction solution due to the encapsulation of Fe 3 O 4 nanospheres, and 84.5% of activity still preserved after the 4th cycle. The main active species involved in Fe 3 O 4 /PBA@PPy-10 system was 1O 2 , while that in reference Fe 3 O 4 /PBA-10 system was OH. Electron spin resonance analysis and radical trapping experiment revealed that the different catalytic mechanisms were attributed to the confinement effect inside the hollow cavity. This work not only presents a feasible way to prepare rarely-reported double-yolk egg-like nanoreactor, but also provides a new insight to solve the bottlenecks in Fenton-like reaction. [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, Co, N atoms co-doped hollow carbon capsules was prepared and used as metal-free catalysts for PMS activation. In Fenton-like reaction, it displayed high degradation rate and outstanding adaptation to full pH range (0–14). [Display omitted] • Fe-Co-N@HCCs displays high PMS activation property in a full range of pH values. • k of Fe-Co-N@HCC is 3.1 and 1.4 times higher than N@HCCs and Fe-N@HCCs. • Contribution of radicals, 1O 2 , electron-transfer path is 13.3%, 30.1%, 56.6%. • PMS is activated on Fe-N 4 and Co-N 4 sites for 1O 2 , Co-N 4 site shows better activity. • Leached Fe and Co ions is 24.9 and 13.6 times lower than Fe-Co-N@HCCs/FeCo. Persulfate (PMS)-based Fenton-like reaction was a highly efficient technique for disposal of organic contaminants. However, high metal leaching and low environmental adaptation were the major concerns for further application. To overcome these two drawbacks, herein, Fe, Co, N atoms co-doped hollow carbon capsules (Fe-Co-N@HCCs) were prepared and used as catalysts for PMS activation. 92.6% of TC was degraded within 40 min and the mineralization efficiency was 55.7%. The degradation rate was 4.7, 3.1 and 1.4 times higher than those of activated carbon, N@HCCs, and Fe-N@HCCs, respectively. Thermodynamic study indicated the TC degradation was an exothermal, chaotic and non-spontaneous process. Radical trapping experiments, electron paramagnetic resonance spectrum, and electrochemical analysis indicated that 1O 2 production and electron-transfer path worked together for PMS activation. DFT calculation indicated that the catalytic activity of Co-N 4 site was higher than Fe-N 4 site for 1O 2 production. Fe-Co-N@HCCs were adapted well to the full pH range (0–14) and complex inorganic anions via non-radical PMS activation paths. Meanwhile, the leached Fe and Co ions were lowered to 0.201 and 0.457 mg/L, satisfying the China emission standard. This work gave a better comprehension on preparation of carbonaceous materials with high environmental adaptation and low leached metal ions for PMS activation. [ABSTRACT FROM AUTHOR]