A facile synthesis of CNTs/Cu2O-CuO heterostructure composites by spray pyrolysis and its visible light responding photocatalytic properties

Highly Selective CO2 Electroreduction to C2H4 Using a Dual-Sites Cu(II) Porphyrin Framework Coupled with Cu2O Nanoparticles via a Synergetic-Tandem Strategy

Low *CO coverage on the active sites is a major hurdle in the tandem electrocatalysis, resulting in unsatisfied C2H4 production efficiencies. In this work, we developed a synergetic-tandem strategy to construct a copper-based composite catalyst for the electroreduction of CO2 to C2H4, which was constructed via the template-directed polymerization of ultrathin Cu(II) porphyrin organic framework incorporating atomically isolated Cu(II) porphyrin and Cu(II) bipyridine sites on a carbon nanotube (CNT) scaffold, and then Cu2O nanoparticles were uniformly dispersed on the CNT scaffold. The presence of dual active sites within the Cu(II) porphyrin organic framework create a synergetic effect, leading to an increase in local *CO availability to enhance the C-C coupling step implemented on the adjacent Cu2O nanoparticles for further C2H4 production. Accordingly, the resultant catalyst affords an exceptional CO2-to-C2H4 Faradaic efficiency (FEC2H4) of 71.0 % at -1.1 V vs reversible hydrogen electrode (RHE), making it one of the most effective copper-based tandem catalysts reported to date. The superior performance of the catalyst is further confirmed through operando infrared spectroscopy and theoretic calculations.

Ru@Carbon Nanotube Composite Microsponge: Fabrication in Supercritical CO2 for Hydrogenation of p-Chloronitrobenzene

Novel heterogeneous catalysts are needed to selectively anchor metal nanoparticles (NPs) into the internal space of carbon nanotubes (CNTs). Here, supercritical CO₂ (SC-CO₂) was used to fabricate the Ru@CNT composite microsponge via impregnation. Under SC-CO₂ conditions, the highly dispersive Ru NPs, with a uniform diameter of 3 nm, were anchored exclusively into the internal space of CNTs. The CNTs are assembled into a microsponge composite. The supercritical temperature for catalyst preparation, catalytic hydrogenation temperature, and time all have a significant impact on the catalytic activity of Ru@CNTs. The best catalytic activity was obtained at 100 °C and 8.0 MPa: this gave excellent selectivity in the hydrogenation of p-chloronitrobenzene at 100 °C. This assembly strategy assisted by SC-CO₂ will be promising for the fabrication of advanced carbon composite powder materials.

Copper Oxide-Based Photocatalysts and Photocathodes: Fundamentals and Recent Advances

This work aims at reviewing the most impactful results obtained on the development of Cu-based photocathodes. The need of a sustainable exploitation of renewable energy sources and the parallel request of reducing pollutant emissions in airborne streams and in waters call for new technologies based on the use of efficient, abundant, low-toxicity and low-cost materials. Photoelectrochemical devices that adopts abundant element-based photoelectrodes might respond to these requests being an enabling technology for the direct use of sunlight to the production of energy fuels form water electrolysis (H2) and CO2 reduction (to alcohols, light hydrocarbons), as well as for the degradation of pollutants. This review analyses the physical chemical properties of Cu2O (and CuO) and the possible strategies to tune them (doping, lattice strain). Combining Cu with other elements in multinary oxides or in composite photoelectrodes is also discussed in detail. Finally, a short overview on the possible applications of these materials is presented.

Rice-Spikelet-like Copper Oxide Decorated with Platinum Stranded in the CNT Network for Electrochemical In Vitro Detection of Serotonin

The specific monitoring of serotonin (ST) has provoked massive interest in therapeutic and biological science since it has been recognized as the third most significant endogenous gastrointestinal neurotransmitter. Hence, there is a great need to develop a sensitive and low-cost sensing platform for the detection of a clinically relevant ST level in biological matrices. Herein, we develop a simple two-step approach for an ultrasensitive electrochemical (EC) sensor with the Cu₂O metal oxide (MO)-incorporated CNT core that has been further deposited with a transitional amount of platinum nanoparticles (Pt NPs). We presented, for the first time, the deposition of Pt NPs on the (CNTs-Cu₂O-CuO) nanopetal composite via the galvanic replacement method, where copper not only acts as a reductant but a sacrificial template as well. The electrocatalytic aptitude of the fabricated EC sensing platform has been assessed for the sensitive detection of ST as a proficient biomarker in early disease diagnostics. The synergy of improved active surface area, remarkable conductivity, polarization effect induced by Pt NPs on CNTs-Cu₂O-CuO nanopetals, fast electron transfer, and mixed-valence states of copper boost up the redox processes at the electrode-analyte junction. The CNTs-Cu₂O-CuO@Pt-modified electrode has unveiled outstanding electrocatalytic capabilities toward ST oxidation in terms of a low detection limit of 3 nM (S/N = 3), wide linear concentration range, reproducibility, and incredible durability. Owing to the amazing proficiency, the proposed EC sensor based on the CNTs-Cu₂O-CuO@Pt heterostructure has been applied for ST detection in biotic fluids and real-time tracking of ST efflux released from various cell lines as early disease diagnostic approaches.

Facile hydrothermal synthesis of CuO–Cu2O/GO nanocomposites for the photocatalytic degradation of organic dye and tetracycline pollutants

A bifunctional nanoscale photocatalyst was constructed by developing a one-step method for the in situ growth of CuO–Cu₂O nanoparticles on GO sheets, and the photocatalytic mechanism was inferred.