Synchronously enhanced dual oxidation pathways via engineered Co-Nx/Co3O4 for high-efficiency degradation of versatile antibiotics.

Developing efficient and eco-friendly technologies for treating the antibiotic wastewaters is crucial. At present, the catalysts with metal-nitrogen (M-Nx) coordination showed excellent Fenton-like performance but were always difficult to realize practical antibiotics degradation because of their complicated preparation methods and inferior stability. In this work, the Co-Nx configuration was facilely reconstructed on the surface of Co3O4 (Co-Nx/Co3O4), which exhibited superior catalytic activity and stability towards various antibiotics. DFT results indicated that stronger ETP oxidation will be triggered by the electron-donating pollutants since more electrons can be easily migrated from these pollutants to the Co-Nx/Co3O4/PMS complex. The Co-Nx/Co3O4/PMS system could maintain superior oxidation capacity, high catalytic stability and anti-interference due to (i) the strong nonradical ETP oxidation with superior degradation selectivity in Co-Nx/Co3O4/PMS system, and (ii) the synchronously enhanced radical oxidation with high populations of non-selective radicals generated via activating PMS by the Co-Nx/Co3O4. As a result, the synergies of synchronously enhanced dual oxidation pathways guaranteed the self-cleaning properties, maintaining 98 % of activity after eight cycles and stability across a wide pH range. Basically, these findings have significant implications for developing technologies for purifying antibiotic wastewater.

Selective and ultrafast oxidation of multiple pollutants by biomorphic diatomite-based catalyst and stable catalytic Fenton-like membrane: Degradation behavior and mechanism analysis.

Carbon-driven advanced oxidations show great potential in water purification, but regulating structures and properties of carbon-based catalysts to achieve ultrafast Fenton-like reactions remains challenging. Herein, a biomorphic diatomite-based catalyst (BD-C) with Si-O doping was prepared using natural diatomite as silicon source and porous template. The results showed that the metal-free BD-C catalyst exhibited ultrafast oxidation performances (0.95-2.58 min-1) towards a variety of pollutants in PMS-based Fenton-like reaction, with the Fenton-like activity of metal-free catalyst comparable to metal-based catalysts or even single-atom catalysts. Pollutants (e.g., CP, BPA, TC, and PCM) with electron-donating groups exhibited extremely low PMS decomposition with overwhelmed electron transfer process (ETP), while high PMS consumption was induced by the addition of electron-withdrawing pollutants (e.g., MNZ and ATZ), which was dominated by radical oxidation. The BD-C/PMS system also showed a high ability to resist the environmental interference. In-depth theoretical investigations demonstrated that the coordination of Si-O can lower the potential barrier of PMS activation for accelerating the generation of radicals, and also promote the electron transfer from pollutants to the BD-C/PMS complexes. In addition, BD-C was deposited onto a polytetrafluoroethylene membrane (PTFEM) with 100% of pollutants removal over 10 h, thereby revealing the promising prospects of utilizing BD-C for practical applications.

In Situ Interfacial Engineering of CeO2 /Bi2 WO6 Heterojunction with Improved Photodegradation of Tetracycline and Organic Dyes: Mechanism Insight and Toxicity Assessment.

The construction of heterojunction photocatalysts is an auspicious approach for enhancing the photocatalytic performance of wastewater treatment. Here, a novel CeO2 /Bi2 WO6 heterojunction is synthesized using an in situ liquid-phase method. The optimal 15% CeO2 /Bi2 WO6 (CBW-15) is found to have the highest photocatalytic activity, achieving a degradation efficiency of 99.21% for tetracycline (TC), 98.43% for Rhodamine B (RhB), and 94.03% for methylene blue (MB). The TC removal rate remained at 95.38% even after five cycles. Through active species capture experiments, •O2 - , h+ , and •OH are the main active substances for TC, RhB, and MB, respectively. The possible degradation pathways for TC are analyzed using liquid chromatography-mass spectrometry (LC-MS). The photoinduced charge transfer and possible degradation mechanisms are proposed through experimentation and density functional theory (DFT) calculations. Toxicity assessment experiments show a significant reduction in toxicity during the TC degradation process. This study uncovers the mechanism of photocatalytic degradation in CeO2 /Bi2 WO6 and provides new insights into toxicity assessment.

Porous CoxP nanosheets decorated Mn0.35Cd0.65S nanoparticles for highly enhanced noble-metal-free photocatalytic H2 generation.

Incorporating 2D transition-metal phosphides into visible-light-driven semiconductors is fascinating for advancing novel photocatalysts. In this paper, porous CoxP nanosheets prepared by phosphating Co(OH)2 nanosheets are coupled with Mn0.35Cd0.65S nanoparticles for significantly boosted photocatalytic H2 evolution performance. The optimal CoxP/Mn0.35Cd0.65S hybrids show an excellent visible-light H2 production rate of 7188.9 µmol g-1h-1 upon visible light with an apparent quantum yield (AQY) of 18.9% at 420 nm. The H2 production rate of the 5% CoxP/Mn0.35Cd0.65S sample is about 257 times bare CdS and even 18 times higher than pristine Mn0.35Cd0.65S. This dramatic photocatalytic H2 generation activity is mainly ascribed to the efficient charge transfer and abundant active sites by introducing the porous CoxP nanosheets. The photocatalytic mechanism of the CoxP/Mn0.35Cd0.65S composites is investigated by the photoluminescence (PL), time-resolved photoluminescence (TRPL), electrochemical, and photoelectrochemical (PEC) tests. This work presents a viable strategy to design a 2D/0D hybrid system containing porous cobalt phosphides nanosheets and MnCdS solid solutions for noble-metal-free photocatalytic application.

Fast one-pot synthesis of a Se-rich MnCdSe solid solution for highly efficient cocatalyst-free photocatalytic H2 evolution.

Designing high-efficiency and stable metal selenides for visible-light-induced photocatalytic H2 production has been challenging. Here, a novel class of Se-rich MnCdSe solid solution with a tunable band structure is fabricated through a fast one-pot strategy. In the absence of any cocatalysts, the optimal MnCdSe nanocrystals exhibit a much higher visible-light-driven H2 evolution activity (2582 µmol g-1 h-1) than the pristine CdSe (30 µmol g-1 h-1), and achieve an apparent quantum yield (AQY) of 7.5% at 420 nm. This work opens a new gateway to explore metal selenide-based solid solutions for photocatalytic applications.

Insights into the role of dual reaction sites for single Ni atom Fenton-like catalyst towards degradation of various organic contaminants.

The trade-off of Fenton-like catalysts in activity and stability remains a challenge in practical remediation applications. In this work, we successfully synthesized an efficient and stable catalyst comprised of single nickel (Ni) atoms dispersed on N-doped porous carbon (named Ni-SAs@CN) through a simple micropore confinement strategy. The catalyst exhibited outstanding catalytic performance with 25.8 min-1 turnover frequency for peroxymonosulfate (PMS) activation toward degradation of various organic pollutants (e.g., antibiotics, dyes, and plasticizers) in a wide pH range (4.5-10.8). Electron paramagnetic resonance and in situ Raman analyses demonstrated that both radical (including SO4•- and •OH) and Ni-PMS* dominated nonradical (via electron transfer) pathways played pivotal role in the decomposition of organics. The X-ray adsorption fine structure analysis and computational pieces of evidence demonstrate that the atomically dispersed NiN4 coordination is the intrinsic catalytic site for PMS activation. Meanwhile, pyrrolic N acts as a functional site to anchor target contaminants to the surface region for oxidation. In this process which is benefited from the dual active sites, the target contaminants were degraded via combined radical and nonradical pathways, which significantly boost the overall oxidation and mineralization kinetics.

Efficient degradation of Bisphenol A by dielectric barrier discharge non-thermal plasma: Performance, degradation pathways and mechanistic consideration.

The discharge of recalcitrant and persistent organic pollutants into the environment and subsequent adverse impacts on the ecosystem has aroused a great concern all over the world. In this study, dielectric barrier discharge (DBD) non-thermal plasma was employed to eliminate bisphenol A (BPA). The influences of several vital experimental parameters, including discharge voltage, initial pH of solution, and rate of water flow on degradation of BPA, were explored in detail. In addition, the real wastewater from pharmaceutical factory was utilized to test the oxidation performance of DBD system. 96.8% chemical oxygen demand removal was achieved using DBD system. Radical quenching experiment as well as electron paramagnetic resonance test demonstrated that •OH was the main reactive oxygen species for the degradation of BPA. Moreover, eight major BPA degradation intermediates were identified by UPLC-MS. Ultimately, based on the UPLC-MS test results, a possible degradation pathway of BPA was proposed.

Enhanced catalytic activation of photo-Fenton process by Cu0·5Mn0·5Fe2O4 for effective removal of organic contaminants.

In this study, Cu0·5Mn0·5Fe2O4 nanoparticles were synthesized through a facile coprecipitation process, evaluated as highly efficient photo-Fenton catalyst for removal of bisphenol A (BPA). Benefit for its larger surface area and unique chemical composition, the Cu0·5Mn0·5Fe2O4 catalyst exhibited superior catalytic activity toward the degradation of BPA, with a rate constant values ranging from 0.247 to 1.090 min-1 based on different operating parameters (catalyst load, initial solution pH, H2O2 concentration and reaction temperature). Importantly, an excellent BPA removal efficiency exceeding 95.2% were obtained after eight successive runs of photo-Fenton process. Electron paramagnetic resonance (EPR) spectroscopy and radical scavenger experiments demonstrated that the hydroxyl radical was the dominant radical in degradation of BPA. A possible BPA degradation pathway was proposed according to the detected intermediates by GC-MS and HPLC. In brief, this work is expected to provide a new heterogeneous photo-Fenton catalyst for the organic pollutants removal from wastewater.

3D Graphene Encapsulated Hollow CoSnO3 Nanoboxes as a High Initial Coulombic Efficiency and Lithium Storage Capacity Anode.

3D Graphene sheets encapsulated amorphous hollow CoSnO3 nanoboxes (H-CoSnO3 @reduced graphene oxide [RGO]) are successfully fabricated by first preparing 3D graphene oxides encapsulated solid CoSn(OH)6 nanocubes, followed by an alkaline etching process and subsequent heating treatment in Ar. The hollow CoSnO3 nanoboxes with average particle size of 230 nm are uniformly and tightly encapsulated by RGO sheets. As an anode material for Li-ion batteries, H-CoSnO3 @RGO displays high initial Coulombic efficiency of 87.1% and large reversible capacity of 1919 mA h g-1 after 500 cycles at the current density of 500 mA g-1 . Moreover, excellent rate capability (1250, 1188, 1141, 1115, 1086, 952, 736, and 528 mA h g-1 at 100, 200, 300, 400, 500, 1000, 2000, and 5000 mA g-1 , respectively) is acquired. The reasons for excellent lithium storage properties of H-CoSnO3 @RGO are discussed in detail.