Preparation of Cu x O/C composite derived from Cu-MOFs as Fenton-like catalyst by two-step calcination strategy

Cu3-xP nanocrystals filled halloysite nanotubes for chemodynamic therapy of breast cancer

Copper-based Fenton-like agents have the ability to convert weakly oxidizing H2O2 into highly oxidizing hydroxyl radicals (·OH) at tumor sites during chemodynamic therapy (CDT). In this study, the interfacial attraction properties between the negatively charged OCP- in sodium phosphathynolate (NaOCP) and the positively charged environment inside the lumen of halloysite nanotubes (HNTs) were utilized to synthesize Cu3-xP nanoparticles in situ within the HNTs. The study investigated the chemical composition, morphology, and structure of Cu3-x P@HNTs. The results indicated uniform distribution of Cu3-xP particles measuring 3-5 nm within HNTs' lumen. Experiments conducted internally and externally to cells confirmed the catalytic capability of Cu3-xP@HNTs to oxidize H2O2 to ·OH. Furthermore, CP@H-CM was synthesized by enclosing Cu3-xP@HNTs in a cancer cell membrane, which selectively targets cancer cells. The experiments revealed the cytotoxicity of CP@H-CM on 4T1 cells. Additionally, the antitumor efficacy of CP@H-CM was evaluated in vivo through tumor recurrence experiments in mice. Moreover, the efficacy of CP@H-CM in repressing tumor growth was enhanced by incorporating infrared laser, indicating a synergistic photodynamic treatment for breast cancer. This study presents an efficacious and viable therapeutic approach to inhibit postoperative tumor reappearance. The implications of this approach are promising, particularly in the domain of tumor treatment and metastasis.

Mixed valence copper oxide composites derived from metal-organic frameworks for efficient visible light fuel denitrification

The construction of heterojunctions has been used to optimize photocatalyst fuel denitrification. In this work, HKUST-1(Cu) was used as a sacrificial template to synthesize a composite material CuxO (CuO/Cu2O) that retains the original MOF framework for photocatalytic fuel denitrification by calcination at different temperatures. By adjusting the temperature, the content of CuO/Cu2O can be changed to control the performance and structure of CuxO-T effectively. The results show that CuxO-300 has the best photocatalytic performance, and its denitrification rate reaches 81% after 4 hours of visible light (≥420 nm) irradiation. Through the experimental analysis of pyridine's infrared and XPS spectra, we found that calcination produces CuxO-T mixed-valence metal oxide, which can create more exposed Lewis acid sites in the HKUST-1(Cu) framework. This leads to improved pyridine adsorption capabilities. The mixed-valence metal oxide forms a type II semiconductor heterojunction, which accelerates carrier separation and promotes photocatalytic activity for pyridine denitrification.

Iron-based metal-organic framework derived pyrolytic materials for effective Fenton-like catalysis: Performance, mechanisms and practicability

In this study, a new catalyst was fabricated by pyrolysis under nitrogen atmosphere with MIL-53(Fe) as the precursor, and was applied to catalyze Fenton-like process. Effects of calcination temperature and pH on decontamination performance, and stability of materials were investigated. Under optimal conditions (calcination temperature of 500 °C and pH of 5.0), the new Fenton-like system remained low iron leaching, and achieved high pseudo-first-order rate constant of 0.0251 min^-1 for bisphenol S (BPS) removal, which is much higher than those in MIL-53(Fe), and nano-Fe₃O₄ catalyzed Fenton-like systems. The superiority of the new catalyst for Fenton-like catalysis was attributed to high specific surface area, as well as formed Fe(II), coordinatively unsaturated iron center and the Fe-O/Fe-C compounds based on the analyses of characterizations. Furthermore, main active species for BPS degradation was identified as hydroxyl radicals, and total hydroxyl radical generation was determined by trapping experiments. The degradation pathways of BPS were also proposed by intermediates monitoring. Moreover, this catalyst showed good potential for practical application, according to the evaluation of reuse, different pollutants degradation, and BPS removal in real wastewater. We believe this study developed a new catalyst with high catalytic activity, high stability and wide application scope, and also sheds light on further development of metal-organic frameworks for Fenton-like catalysis.

Micro/macrostructure and multicomponent design of catalysts by MOF-derived strategy: Opportunities for the application of nanomaterials-based advanced oxidation processes in wastewater treatment

Advanced oxidation processes (AOPs) have demonstrated an effective wastewater treatment method. But the application of AOPs using nanomaterials as catalysts is challenged with a series of problems, including limited mass transfer, surface fouling, poor stability, and difficult recycling. Recently, metal-organic frameworks (MOFs) with high tunability and ultrahigh porosity are emerging as excellent precursors for the delicate design of the structure/composition of catalysts and many MOF-derived catalysts with distinct physicochemical characteristics have shown optimized performance in various AOPs. Herein, to elucidate the structure-composition-performance relationship, a review on the performance optimization of MOF-derived catalysts to overcome the existing problems in AOPs by micro/macrostructure and multicomponent design is given. Impressively, MOF-derived strategy for the design of catalyst materials from the aspects of microstructure, macrostructure, and multicomponent (polymetallic, heteroatom doping, M/C hybrids, etc.) is firstly presented. Moreover, important advances of MOF-derived catalysts in the application of various AOPs (Fenton, persulfate-based AOPs, photocatalysis, electrochemical processes, hybrid AOPs) are summarized. The relationship between the unique micro/macrostructure and/or multicomponent features and performance optimization in mass transfer, catalytic efficiency, stability, and recyclability is clarified. Furthermore, the challenges and future work directions for the practical application of MOF-derived catalysts in AOPs for wastewater treatment are provided.

Degradation of sulfamerazine by a novel CuxO@C composite derived from Cu-MOFs under air aeration

Most metal-organic frameworks (MOFs) are synthesized from carboxylate and metal precursors by hydrothermal process, which will consume a large amount of solvent and carboxylate. To address this issue, a new strategy for Cu-based MOFs was developed, in which the Cu-based MOFs was obtained by using abundant natural polymer (tannic acid) as one of the precursors and using high-energy ball milling to achieve a self-assembly of tannic acid and copper sulfate. Based on this strategy, a novel Cu-based MOFs derivative (Cu_xO@C composite) was synthesized by high-temperature sintering of Cu-based MOFs and used for sulfamerazine (SMR) removal via O₂ activation. The BET specific surface area and average pore size of Cu_xO@C composite were 110.34 m² g^-1 and 21.06 nm, respectively, which made Cu_xO@C composite had the maximum adsorption capacity (Q_max) for SMR of 104.65 mg g^-1 and favored the subsequent degradation of SMR. The results from XRD and XPS indicated that Cu_xO@C composite contained a lot of Cu⁰ and Cu₂O with the sizes of 76.6 nm and 9.8 nm, respectively, which led to its high performance of O₂ activation. The removal efficiency of SMR and 90.2% TOC achieved 100% and 90.2%, respectively in the Cu_xO@C/air system at initial pH of 4.0, air flow rate of 100 mL min^-1, Cu_xO@C dosage of 1 g L^-1 and reaction time of 30 min. Reactive species, including H₂O₂, OH and O₂^- radicals were detected in the Cu_xO@C/air system, and OH and O₂^- were mainly responsible for the degradation of SMR.

Synthesis, modification and bioapplications of nanoscale copper chalcogenides

Copper chalcogenides have a simple general formula, variable atomic ratios, and complicated crystal structures, which lead to their wealth of optical, electrical, and magnetic properties with great potential for wide applications ranging from energy conversion to the biomedical field. Herein, we summarize the recent advances in (1) the synthesis of size- and morphology tunable nanostructures by different methods; (2) surface modification and functionalization for different purposes; and (3) bioapplications for diagnosis and treatment of tumors by different imaging and therapy methods, as well as antibacterial applications. We also briefly discuss the future directions and challenges of copper chalcogenide nanoparticles in the biomedical field.

More octahedral Cu+ and surface acid sites in uniformly porous Cu-Al2O3 for enhanced Fenton catalytic performances

Porous Cu-doped alumina (P-Cu-Al₂O₃) has been synthesized using ammonium chloride as a green gaseous template. The unique pore-forming agent endows the catalyst a large surface area and homogenous pore structure. According to the characterization results by multi-technologies, the highly dispersed framework Cu⁺/Cu²⁺ was incorporated in octahedral sites with the formation of the Cu-O-Al bonds. Compared with bulk Cu-doped Al₂O₃ (B-Cu-Al₂O₃), more surface acidic oxygen-containing groups and Lewis acid sites existed in P-Cu-Al₂O₃, resulting in the production of surface adsorbed ^•OH, which is helpful for the removal of surface adsorbed organic intermediates. In addition, O₂ more easily participate in surface reaction to promote the ^•OH generation in P-Cu-Al₂O₃ system than that in B-Cu-Al₂O₃. As a result, the representative endocrine disruptor bisphenol A can be more efficiently mineralized by P-Cu-Al₂O₃. This work provides a facile route to develop porous active heterogenous Fenton-like catalysts and a unique perspective to insight into the structure-activity relationship.

Catalytic activation of O2 by Al0-CNTs-Cu2O composite for Fenton-like degradation of sulfamerazine antibiotic at wide pH range

In this study, a novel Al°-CNTs-Cu₂O composite, capable of activating O₂ to generate H₂O₂ and further to reactive oxygen species (ROSs) at a wide pH range, was synthetized, characterized and applied for the degradation of sulfamerazine. In the activation of O₂ by Al°-CNTs-Cu₂O composite, H₂O₂ was generated from the reaction of O₂ with Al°-CNTs, which could be catalytically decomposed into O₂^- and OH by Cu₂O, the formed Cu(II) could be rapidly reduced to Cu₂O by Al°-CNTs in composite, which made Al°-CNTs-Cu₂O composite reusable and decreased the leaching of copper ions into solution. The removal efficiency of SMR and TOC was 73.91 % and 56.80 %, respectively at initial pH = 5.8, T = 20 °C, O₂ flow rate = 100 mL/min, Al°-CNTs-Cu₂O dosage = 2 g/L, SMR = 50 mg/L, and reaction time = 60 min. The removal efficiency of SMR kept almost unchanged and the concentration of copper ions in solution was below 0.5 mg/L. The Al°-CNTs-Cu₂O/O₂ process could be used as a novel catalyst for the degradation of refractory organic contaminants in water and wastewater by Fenton-like process at a wide pH range through the in situ generation of H₂O₂.

Fe-MOFs prepared with the DBD plasma method for efficient Fenton catalysis

Fe-MOFs were successfully synthesized with the dielectric barrier discharge (DBD) plasma method, and applied for degradation of methyl orange by the Fenton process. Fe-MOFs were characterized by XRD, SEM, EDS, BET and FT-IR. A systematic study was carried out to optimize the synthesis conditions, taking into account the Fenton capacity performance for degradation of methyl orange. The optimal synthesis conditions were a discharge time of 100 min, discharge voltage of 18 kV, reactant concentration of 14 g L⁻¹ and reactant mass ratio (TA : FeCl₃·6H₂O) of 1 : 5, with influence on the crystallization, morphologies and particle size. The degradation rate of methyl orange could reach 85% within 40 min with the MO concentration of 50 mg L⁻¹, Fe-MOF dosage of 0.12 g L⁻¹, pH of 5 and H₂O₂ at 1 mL L⁻¹. Meanwhile, the Fenton catalytic process was conducted covering a range of catalyst concentrations, initial MO concentrations, pH and H₂O₂ amounts. Higher catalyst concentration, lower MO initial concentration, pH of 3 and H₂O₂ amount of 1 mL L⁻¹ were conducive to the degradation efficiency.

Fe-MOFs were successfully synthesized with the dielectric barrier discharge (DBD) plasma method, and applied for degradation of methyl orange by the Fenton process.