Morphology-dependent sensing performance of CuO nanomaterials

Optimized Copper-Based Microfeathers for Glucose Detection

Diabetes is expected to rise substantially by 2045, prompting extensive research into accessible glucose electrochemical sensors, especially those based on non-enzymatic materials. In this context, advancing the knowledge of stable metal-based compounds as alternatives to non-enzymatic sensors becomes a scientific challenge. Nonetheless, these materials have encountered difficulties in maintaining stable responses under physiological conditions. This work aims to advance knowledge related to the synthesis and characterization of copper-based electrodes for glucose detection. The microelectrode presented here exhibits a wide linear range and a sensitivity of 1009 µA∙cm-2∙mM-1, overperfoming the results reported in literature so far. This electrode material has also demonstrated outstanding results in terms of reproducibility, repeatability, and stability, thereby meeting ISO 15197:2015 standards. Our study guides future research on next-generation sensors that combine copper with other materials to enhance activity in neutral media.

Effectiveness of different CuO morphologies nanomaterials on the permeability, antifouling, and mechanical properties of PVDF/PVP/CuO ultrafiltration membrane for water treatment

The hydrophobic nature of Poly (vinylidene fluoride) (PVDF) is a significant barrier to use in ultrafiltration, resulting in fouling, flux decline, and reduced lifespan in water treatment. This study examines the effectiveness of different morphologies of CuO nanomaterials (NMs) (spherical, rod, plate, and flower), synthesized by the facile hydrothermal method, to modify PVDF membrane with PVP additive for improving the performance of water permeability and antifouling. Such membrane configurations with different morphologies of CuO NMs improved hydrophilicity with a maximum water flux of 222-263 L m-2h-1 compared to 195 L m-2h-1 for the bare membrane and exhibited excellent thermal and mechanical strengths. The characterization results exhibited that plate-like CuO NMs were dispersed uniformly in the membrane matrix, and their incorporation as a composite improved the membrane properties. From the antifouling test with the bovine serum albumin (BSA) solution, the membrane with plate-like CuO NMs had the highest flux recovery ratio (FRR) (∼91%) and the lowest irreversible fouling ratio (∼10%). The antifouling enhancement was due to less interaction between modified membranes and foulant. Further, the nanocomposite membrane showed excellent stability and negligible Cu2+ ion leaching. Overall, our findings provide a new strategy for developing inorganic nanocomposite PVDF membranes for water treatment.

Recent innovations in the technology and applications of low-dimensional CuO nanostructures for sensing, energy and catalysis

Low-dimensional copper oxide nanostructures are very promising building blocks for various functional materials targeting high-demanded applications, including energy harvesting and transformation systems, sensing and catalysis. Featuring a very high surface-to-volume ratio and high chemical reactivity, these materials have attracted wide interest from researchers. Currently, extensive research on the fabrication and applications of copper oxide nanostructures ensures the fast progression of this technology. In this article we briefly outline some of the most recent, mostly within the past two years, innovations in well-established fabrication technologies, including oxygen plasma-based methods, self-assembly and electric-field assisted growth, electrospinning and thermal oxidation approaches. Recent progress in several key types of leading-edge applications of CuO nanostructures, mostly for energy, sensing and catalysis, is also reviewed. Besides, we briefly outline and stress novel insights into the effect of various process parameters on the growth of low-dimensional copper oxide nanostructures, such as the heating rate, oxygen flow, and roughness of the substrates. These insights play a key role in establishing links between the structure, properties and performance of the nanomaterials, as well as finding the cost-and-benefit balance for techniques that are capable of fabricating low-dimensional CuO with the desired properties and facilitating their integration into more intricate material architectures and devices without the loss of original properties and function.

Recent advances in perovskite oxides for non-enzymatic electrochemical sensors: A review

Non-enzymatic electrochemical sensors with significant advantages of high sensitivity, long-term stability, and excellent reproducibility, are one promising technology to solve many challenges, such as the detection of toxic substances and viruses. Among various materials, perovskite oxides have become a promising candidate for use in non-enzymatic electrochemical sensors because of their low cost, flexible structure, and high intrinsic catalytic activity. A comprehensive overview of the recent advances in perovskite oxides for non-enzymatic electrochemical sensors is provided, which includes the synthesis methods of nanostructured perovskites and the electrocatalytic mechanisms of perovskite catalysts. The better sensing performance of perovskite oxides is mainly due to the lattice O vacancies and superoxide oxygen ions (O₂^2-/O^-), which are generated by the transfer of lattice oxygen to adsorbed -OH and have performed excellent properties suitable for electrooxidation of analytes. However, the limited electron transfer kinetics, stability, and selectivity of perovskite oxides alone make perovskite oxides far from ready for scientific development. Therefore, composites of perovskite oxides with other materials like graphitic carbon, metals, metal compounds, conducting organics, and biomolecules are summarized. Furthermore, a brief section describing the future challenges and the corresponding recommendation is presented in this review.

Porous nitrogen-doped reduced graphene oxide-supported CuO@Cu2O hybrid electrodes for highly sensitive enzyme-free glucose biosensor

Constructing high-performance enzyme-free biosensors for detecting glucose is essential to preliminary diabetes diagnosis. Here, copper oxide nanoparticles (CuO@Cu₂O NPs) were anchored in porous nitrogen-doped reduced graphene oxide (PNrGO) to construct CuO@Cu₂O/PNrGO/GCE hybrid electrode for sensitive detection of glucose. Benefiting from the remarkable synergistic effects between the multiple high activation sites of CuO@Cu₂O NPs and the dramatic properties of PNrGO with excellent conductivity and large surface area with many accessible pores, the hybrid electrode possesses outstanding glucose sensing performance that is far superior to those of pristine CuO@Cu₂O electrode. The as-fabricated enzyme-free glucose biosensor displays prominent glucose sensitivity of 2,906.07 μA mM^-1 cm^-2, extremely low limit of detection of 0.13 μM, and wide linear detection of 3 μM-6.772 mM. In addition, excellent reproducibility, favorable long-term stability, and distinguished selectivity are obtained in the glucose detection. Importantly, this study provides promising results for continuous improvement of non-enzyme sensing applications.

Electrochemical detection of hydrogen peroxide using micro and nanoporous CeO2 catalysts

In this research work, focus has been made on a glassy carbon electrode (GCE) modified commercial micro and synthesized nano-CeO₂ for the detection of hydrogen peroxide (H₂O₂). Firstly, CeO₂ nanoleaves were prepared by solvothermal route. Both commercially available micro CeO₂ and synthesized nano-CeO₂ structures were analyzed by different characterization techniques. The Raman spectra of synthesized nano CeO₂ has more oxygen vacancies than micro CeO₂. SEM images revealed that the synthesized CeO₂ acquired leaf-like morphology. The catalyst nano CeO₂ offered mesoporosity from nitrogen adsorption-desorption isotherms with massive sites of activation for increasing efficiency. Experiments on determining H₂O₂ using micro CeO₂ or nano-CeO₂/GCE was conducted using cyclic voltammetry (CV) and amperometry. Enhanced H₂O₂ reduction peak current with lower potential was observed in nano-CeO₂/GCE. The influence of scan rate and H₂O₂ concentration on the performance of nano-CeO₂/GCE were also studied. The obtained results have indicated that nano-CeO₂/GCE showed improved electrochemical sensing behavior towards the reduction of H₂O₂ than micro-CeO₂/GCE and bare GCE. A linear relationship was obtained over 0.001 μM-0.125 μM concentration of H₂O₂, with good sensitivity 141.96 μA μM^-1 and low detection limit of 0.4 nM. Hence, the present nano-CeO₂ system will have a great potential with solvothermal synthesis approach in the development of electrochemical sensors.

Non-Enzymatic Amperometric Glucose Screen-Printed Sensors Based on Copper and Copper Oxide Particles

Non-enzymatic amperometric glucose sensors have gained much attention in the past decade because of the better chemical and thermal stability and biocompatibility compared to conventional sensors based on the use of biomolecules. This study focuses on a novel copper and copper oxide-based glucose sensor synthesized by an electrodeposition technique through a rigorous protocol which reports an excellent analytical performance due to its structure and its increased active area. In addition, the linear response range, detection limit and sensitivity were 0.5–5.0 mmol L−1, 0.002 mmol L−1, 904 μA mmol−1 L−1 cm−2, respectively. Results show a reliable electrode as it is chemically stable, exhibits rapid and excellent sensitivity, and it is not significantly affected by coexisting species present in the blood samples; furthermore, it reports a maximum relative standard deviation error (RSD) of 6%, and showed long operating life as the electrode was used for thousand measurements of 4.0 mmol L−1 glucose solution during three days.