Cu-MOF derived Cu-C nanocomposites towards high performance electrochemical supercapacitors

Cu Anchored Carbon Nitride (Cu/CN) Catalyzes Selective Oxidation of Thiol by Controlling Reactive Oxygen Species Generation

Production of H2O2 using heterogeneous semiconductor photocatalysts has emerged as an ecofriendly and practical approach across various applications, ranging from environmental detoxification to fuel cells and chemical synthesis. Extensive efforts have been devoted to engineering semiconductors to enhance their catalytic capabilities for H2O2 production. However, in chemical synthesis, the utilization of the potent oxidant H2O2 can present challenges in selectively oxidizing organic compounds. In this study, we introduce copper atoms into carbon nitride (Cu/CN), facilitating the generation of hydroperoxyl radicals (·OOH) as primary reactive oxidants and offering reaction conditions entirely devoid of H2O2 via the Fenton reaction. Cu/CN demonstrates selective oxidation of thiols to disulfides, in contrast to other current heterogeneous photocatalysts that yield undesired overoxidized side products, such as thiosulfinate and thiosulfonate. Cu/CN's controllable capacity for specific ROS generation, broad substrate scopes, and recyclability empower greener and highly selective photooxidation of organic compounds.

Biomimetic synthesis of RPL14B-based CdSe quantum dots for the detection of heavy metal copper ions

In the present study, an Escherichia coli-expressed yeast ribosomal protein was used as a template for synthesizing RPL14B-based CdSe quantum dots in vitro via the quasi-biosynthesis strategy at low temperature. The synthetic bionic RPL14B-based CdSe quantum dots were characterized using TEM, HRTEM, and EDX spectra, and the results showed that the synthesized quantum dots were CdSe quantum dots with a crystal face spacing of 0.21 and 0.18 nm. The biomimetic method-synthesized quantum dots exhibited the characteristics of a uniform particle size, good dispersion, and strong photobleaching resistance. Moreover, the fluorescence of the RPL14b-based CdSe quantum dots could be specifically quenched using Cu2+ in a linear range of 0.2-10 μM. Finally, these RPL14b-based CdSe quantum dots can be used for the specific detection of heavy metal copper ions in addition to other applications in biological analyses.

Boosting the Capacitor Performance of the Metal Organic Frameworks Derived V2O5 Nanoflower by Cu Doping

Due to its ultrahigh theoretical capacitance, vanadium pentoxide (V2O5) is considered to be a valid candidate for advanced supercapacitors. However, because of the low electron/electrolyte transfer rate, the capacitive performance still remains to be improved. In this report, Cu doping is adopted to improve the capacitive performance by a two-steps strategy consisting of microwave-assisted solvothermal and postannealing treatments. The electrochemical results indicate that the Cu doping was beneficial for improving the specific capacitance, extending the potential window, and improving the rate ability and long-term stability of V2O5. Furthermore, the mechanism for the performance improvement is explained in detail by combining theoretical calculation and experiments. The results indicated that, compared with that of undoped V2O5, the larger interplanar spacing, better electrical conductivity, a larger proportion of V3+/V4+, and more abundant oxygen vacancies result in an improved capacitive performance. Our proposed Cu-doped V2O5 (Cu-V2O5) can be used as both a positive electrode and a negative electrode for the assembly of the symmetric supercapacitor, which can be used as an energy storage device for light emitting diode lamps.

Phosphorization Engineering on a MOF-Derived Metal Phosphide Heterostructure (Cu/Cu3P@NC) as an Electrode for Enhanced Supercapacitor Performance

A highly conductive and rationally constructed metal-organic framework (MOF)-derived metal phosphide with a carbonaceous nanostructure is a meticulous architecture toward the development of electrode materials for energy storage devices. Herein, we report a facile strategy to design and construct a new three-dimensional (3D) Cu-MOF via a solvent diffusion method at ambient temperature, which was authenticated by a single-crystal X-ray diffraction study, revealing a novel topology of (2,4,7)-connected three-nodal net named smm4. Nevertheless, the poor conductivity of pristine MOFs is a major bottleneck hindering their capacitance. To overcome this, we demonstrated an MOF-derived Cu3P/Cu@NC heterostructure via low-temperature phosphorization of Cu-MOF. The electronic and ionic diffusion kinetics in Cu3P/Cu@NC were improved due to the synergistic effects of the heterostructure. The as-prepared Cu3P/Cu@NC heterostructure electrode delivers a specific capacity of 540 C g-1 at 1 A g-1 with outstanding rate performance (190 C g-1 at 20 A g-1) and cycle stability (91% capacity retention after 10,000 cycles). Moreover, the assembled asymmetric solid-state supercapacitor (ASC) achieved a high energy density/power density of 45.5 Wh kg-1/7.98 kW kg-1 with a wide operating voltage (1.6 V). Long-term stable capacity retention (87.2%) was accomplished after 5000 cycles. These robust electrochemical performances suggest that the Cu3P/Cu@NC heterostructure is a suitable electrode material for supercapacitor applications.

Green carbon-carbon homocoupling of terminal alkynes by a silica supported Cu(II)-hydrazone coordination compound

A Cu(II) complex, [Cu(HL)(NO₃)(CH₃OH)]·CH₃OH (1), was obtained by the reaction of Cu(NO₃)₂·3H₂O and H2L in methanol solvent (H2L is (E)-4-amino-N'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide). H2L and compound 1 were characterized by various spectroscopic analyses and the molecular structure of [Cu(HL)(NO₃)(CH₃OH)]·CH₃OH was determined by single-crystal X-ray analysis. The results indicated the product is a mononuclear Cu(II) complex and contains a free NH₂ functional group on the structure of the ligand. [Cu(HL)(NO₃)(CH₃OH)]·CH₃OH was used for the preparation of a heterogeneous catalyst by supporting it on functionalized silica gel. The heterogeneous catalyst (Si-Cu) was prepared by an amidification reaction of [Cu(HL)(NO₃)(CH₃OH)]·CH₃OH with functionalized silica gel. The resulting silica-supported catalyst (Si-Cu) was characterized by TGA, FT-IR, EPR, DRS, EDS, XRD, SEM and XPS analyses. Si-Cu was employed in a carbon-carbon coupling reaction and the effects of the amount of Si-Cu and temperature were investigated in the catalytic coupling. The structure of one of the products of the catalytic reactions (C₁₆H₂₂O₂, CP1) was determined by single-crystal X-ray analysis, which proved the formation of a C-C bond and the production of di-acetylene by homocoupling of terminal alkyne. This catalytic system is stable and it can be reused for a coupling reaction without a significant change in its catalytic activity.

Covalent Grafting of Dielectric Films on Cu(111) Surface via Electrochemical Reduction of Aryl Diazonium Salts

Covalent grafting of dielectric films containing polyhedral oligomeric silsesquioxane (POSS) on the surface of Cu(111) is performed by a one-step electrochemical reduction of diazonium salts. This method is efficient and economic and performs in a proton-polar solvent of deionized water and tetrahydrofuran (THF), where the monomer employs an octavinylsilsesquioxane (OVS) containing a POSS core. The eight vinyl bonds contained in OVS are used to participate in aryl radical-initiated polymerization reactions to form films. The formed film is dense and covers the copper surface completely and uniformly. The thickness of the film can be controlled by adjusting the reaction time. The components of the films are mainly polynitrophenyl (PNP) or polyaminophenyl (PAP) as well as poly(octavinylsilsesquioxane) (POVS), and the POVS content could be adjusted by the applied voltage. The introduction of POSS prevents the copper surface from being oxidized and often gives the film good properties such as good dielectric properties, mechanical properties, and thermal properties. In addition, the presence of Cu-O-C and Cu-C bonds between the film and copper interface is confirmed at different film thicknesses by X-ray photoelectron spectroscopy (XPS), which allowed the construction of covalent bonds between metal and nonmetal, further enhancing the bonding between the film and copper. Organic films prepared by electrochemical reduction of diazonium salts using OVS as a monomer will have potential significance for the future development of the electronics industry.

Facile synthesis of PEDOT-rGO/HKUST-1 for high performance symmetrical supercapacitor device

A novel poly(3,4-ethylenedioxythiophene)-reduced graphene oxide/copper-based metal-organic framework (PrGO/HKUST-1) has been successfully fabricated by incorporating electrochemically synthesized poly(3,4-ethylenedioxythiophene)-reduced graphene oxide (PrGO) and hydrothermally synthesized copper-based metal-organic framework (HKUST-1). The field emission scanning microscopy (FESEM) and elemental mapping analysis revealed an even distribution of poly(3,4-ethylenedioxythiophene) (PEDOT), reduced graphene oxide (rGO) and HKUST-1. The crystalline structure and vibration modes of PrGO/HKUST-1 were validated utilizing X-ray diffraction (XRD) as well as Raman spectroscopy, respectively. A remarkable specific capacitance (360.5 F/g) was obtained for PrGO/HKUST-1 compared to HKUST-1 (103.1 F/g), PrGO (98.5 F/g) and PEDOT (50.8 F/g) using KCl/PVA as a gel electrolyte. Moreover, PrGO/HKUST-1 composite with the longest charge/discharge time displayed excellent specific energy (21.0 Wh/kg), specific power (479.7 W/kg) and an outstanding cycle life (95.5%) over 4000 cycles. Thus, the PrGO/HKUST-1 can be recognized as a promising energy storage material.

HKUST-1 derived Cu@CuOx/carbon catalyst for base-free aerobic oxidative coupling of benzophenone imine: high catalytic efficiency and excellent regeneration performance

The oxidative coupling of imines to ketazine with molecular oxygen is a green process towards the synthesis of hydrazine or hydrazine hydrate, which could efficiently address the economic and environmental issues of the traditional Raschig or peroxide-ketazine process. Herein, we developed an efficient heterogeneous base-free benzophenone imine oxidative coupling route with O₂ catalyzed by Cu/CuO_x/carbon materials derived from MOFs under mild conditions. Under optimized conditions, the conversion of BI is up to 98.2% and the selectivity of ketamine is 94.9%. This catalyst has excellent structure stability, recycling, and regeneration performance, owing to the carbonization of organic ligands of MOF at high temperature. More importantly, it is confirmed that the metallic Cu core is essential to improve the catalytic performance of the CuO shell in the BI oxidative coupling reaction, due to the promotion of electron transfer in the CuO surface, making dissolved O₂ molecules more easily insert oxygen vacancies. This strategy might open an avenue to the sustainable catalytic synthesis of hydrazine or hydrazine hydrate.

The oxidative coupling of imines to ketazine with molecular oxygen is a green process towards hydrazine hydrate synthesis, which could efficiently address the environmental and economic issues of the traditional Raschig or peroxide-ketazine process.