Synthesis of porous NiO/CeO2 hybrid nanoflake arrays as a platform for electrochemical biosensing

CeO2/CuO/NiO hybrid nanostructures loaded on N-doped reduced graphene oxide nanosheets as an efficient electrocatalyst for water oxidation and non-enzymatic glucose detection

In this work, the three-component heterostructure of CeO₂/CuO/NiO was synthesized by a co-precipitation procedure and heating at a temperature of 750 °C. Then, CeO₂/CuO/NiO nanoparticles were successfully supported on N-doped reduced graphene oxide (N-rGO) by a hydrothermal method. The obtained nanomaterials were used as effective electrocatalysts for the oxygen evolution reaction and glucose sensing in an alkaline medium. The results indicated that when CeO₂/CuO/NiO is anchored on N-rGO nanosheets, active catalytic sites increase. On the other hand, N-doped rGO enhances electrical conductivity and electron transfer for water or glucose oxidation. CeO₂/CuO/NiO@N-rGO has a large electrochemically active surface area and more active catalytic positions, and thus exhibits high activity for the OER with a low overpotential of 290 mV, a suitable Tafel slope of 110 mV dec^-1, and superior stability and durability for at least 10 hours. CeO₂/CuO/NiO@N-rGO can also detect glucose with a high sensitivity of 912.7 μA mM^-1 cm^-2, a low detection limit of 0.053 μM, a wide linear range between 0.001 and 24 mM, and a short response time of about 2.9 s. Moreover, the high selectivity and stability of this electrode for glucose sensing show its potential for clinical applications.

Enhanced activity promoted by amorphous metal oxyhydroxides on CeO2 for alkaline oxygen evolution reaction

Herein, we demonstrate a direct growth of amorphous metal oxyhydroxide (AMO) attached on CeO₂ by a galvanic replacement mechanism as advanced oxygen evolution reaction (OER) catalyst. In this unique structure, the CeO₂ substrate not only offers high specific surface area for the formation of AMO, but also provides high conductivity, guaranteeing the promoted electron transfer for the catalytic reaction. In addition, the AMO on the surface of the CeO₂ exposes abundant active sites for the OER. Benefiting from the above advantages, the as-prepared AMO@CeO₂ supported on nickel foam (AMO@CeO₂/NF) exhibits excellent OER performance with low overpotential of 261 mV at 10 mA cm^-2, high turnover frequency of 0.07 s^-1 at 20 mA cm^-2 and superior stability in 1.0 M KOH.

Nanoceria, the versatile nanoparticles: Promising biomedical applications

Nanotechnology has been a boon for the biomedical field due to the freedom it provides for tailoring of pharmacokinetic properties of different drug molecules. Nanomedicine is the medical application of nanotechnology for the diagnosis, treatment and/or management of the diseases. Cerium oxide nanoparticles (CNPs) are metal oxide-based nanoparticles (NPs) which possess outstanding reactive oxygen species (ROS) scavenging activities primarily due to the availability of "oxidation switch" on their surface. These NP have been found to protect from a number of disorders with a background of oxidative stress such as cancer, diabetes etc. In fact, the CNPs have been found to possess the environment-dependent ROS modulating properties. In addition, the inherent catalase, SOD, oxidase, peroxidase and phosphatase mimetic properties of CNPs provide them superiority over a number of NPs. Further, chemical reactivity of CNPs seems to be a function of their surface chemistry which can be precisely tuned by defect engineering. However, the contradictory reports make it necessary to critically evaluate the potential of CNPs, in the light of available literature. The review is aimed at probing the feasibility of CNPs to push towards the clinical studies. Further, we have also covered and censoriously discussed the suspected negative impacts of CNPs before making our way to a consensus. This review aims to be a comprehensive, authoritative, critical, and accessible review of general interest to the scientific community.

Oriented and robust anchoring of Fe via anodic interfacial coordination assembly on ultrathin Co hydroxides for efficient water oxidation

The oriented distribution and strong bonding of Fe active sites in multiple metal hydroxides are crucial to modulate activity and stability for efficient oxygen evolution reaction (OER). However, the dispersion and inevitable dissolution of Fe species still need to be addressed through deliberate design. Here, trace amounts of Fe chelated with tannic acid (TA) are precisely anchored to ultrathin Co hydroxides (TF@Co(OH)₂-t) through a new anodic interfacial coordination assembly strategy: firstly, the ZIF-67@Co(OH)₂ precursor with ultrathin Co(OH)₂ nanosheets vertically grown on the shell, provides abundant active sites and sufficient anchoring regions for subsequent TA-Fe coating; secondly, the TA-Fe ligand network quickly and robustly coats the surface of the Co(OH)₂via positive potential-driven chronopotentiometry, yielding TF@Co(OH)₂-t with good dispersion and controllable Fe species. The TA-Fe network efficiently activates Co species and prevents the dissolution of Fe ions. Physical characterization and DFT simulations reveal that the optimized OER activity with 317 mV at 10 mA cm^-2 for TF@Co(OH)₂-500 can be attributed to the accelerated electron transfer, increased active sites, and the moderate fall in d-band center levels due to Fe integration. Moreover, prolonged stability is realized benefiting from the robust TA-Fe coating protecting the actives sites.

2D Electron Gas and Oxygen Vacancy Induced High Oxygen Evolution Performances for Advanced Co3 O4 /CeO2 Nanohybrids

The rational design of atomic-scale interfaces in multiphase nanohybrids is an alluring and challenging approach to develop advanced electrocatalysts. Herein, through the selection of two different metal oxides with particular intrinsic features, advanced Co₃ O₄ /CeO₂ nanohybrids (NHs) with CeO₂ nanocubes anchored on Co₃ O₄ nanosheets are developed, which show not only high oxygen vacancy concentration but also remarkable 2D electron gas (2DEG) behavior with ≈0.79 ± 0.1 excess e^- /u.c. on the Ce³⁺ sites at the Co₃ O₄ -CeO₂ interface. Such a 2DEG transport channel leads to a high carrier density of 3.8 × 10¹⁴ cm^-2 and good conductivity. Consequently, the Co₃ O₄ /CeO₂ NHs demonstrate dramatically enhanced oxygen evolution reaction (OER) performances with a low overpotential of 270 mV at 10 mA cm^-2 and a high turnover frequency of 0.25 s^-1 when compared to those of pure Co₃ O₄ and CeO₂ counterparts, outperforming commercial IrO₂ and some recently reported representative OER catalysts. These results demonstrate the validity of tailoring the electrocatalytic properties of metal oxides by 2DEG engineering, offering a step forward in the design of advanced hybrid nanostructures.

Interface engineering of a CeO2-Cu3P nanoarray for efficient alkaline hydrogen evolution

It is of great importance to design and develop highly active electrocatalysts for the hydrogen evolution reaction (HER) under alkaline conditions. In this work, we report the development of a CeO₂-Cu₃P nanoarray supported on nickel foam (CeO₂-Cu₃P/NF) as an excellent HER catalyst with the demand of an overpotential of only 148 mV to deliver a geometrical catalytic current density of 20 mA cm^-2 in 1.0 M KOH. Remarkably, this catalyst also shows strong long-term electrochemical durability for at least 100 h with nearly 100% Faradaic efficiency. Density functional theory calculations reveal that the CeO₂-Cu₃P/NF hybrid has a lower water dissociation energy and a more thermo-neutral hydrogen adsorption free energy.

A 3D porous Ni-CeO2 nanosheet array as a highly efficient electrocatalyst toward alkaline hydrogen evolution

A 3D porous Ni-CeO₂ nanosheet array supported on a Ti mesh (Ni-CeO₂/TM) behaves as an efficient and stable alkaline HER electrocatalyst, offering a current density of 10 mA cm⁻² at an overpotential of 67 mV.

Morphology-dependent oxygen vacancies and synergistic effects of Ni/CeO2 catalysts for N2O decomposition

Strong morphology-dependent oxygen vacancies and synergistic effects of Ni/CeO₂ catalysts and their vital effects on N₂O decomposition.

High-performance alkaline hydrogen evolution electrocatalyzed by a Ni3N–CeO2 nanohybrid

A Ni₃N–CeO₂/TM nanohybrid shows high activity and durability for the alkaline hydrogen evolution reaction, offering 10 mA cm⁻² at an overpotential of 80 mV.

Co3O4@CeO2 hybrid flower-like microspheres: a strong synergistic peroxidase-mimicking artificial enzyme with high sensitivity for glucose detection

In recent years, the development of artificial nanostructured enzymes has received enormous interest in nanobiotechnology due to their advantages over natural enzymes. In the present work, different amounts (5, 10, and 20 wt%) of Co₃O₄ nanoparticle decorated CeO₂ hybrid flower-like microspheres (Co₃O₄@CeO₂) have been investigated for peroxidase-like activity and it was found that 10 wt% of Co₃O₄@CeO₂ exhibited excellent peroxidase-like activity for the catalytic oxidation of the 3,3',5,5'-tetramethylbenzidine (TMB) substrate in the presence of H₂O₂. The formation of more Ce³⁺ ions associated with the oxygen vacancies and a strong synergistic interaction between CeO₂ and Co₃O₄ may be responsible for the enhanced peroxidase-like activity. Based on their peroxidase activity, Co₃O₄@CeO₂ hybrid microspheres were used for the colourimetric detection of glucose. It was found that Co₃O₄@CeO₂ hybrid microspheres showed a substantial enhancement in the detection selectivity. The limit of detection (LOD) was also improved with a limit as low as 1.9 μM. Thus, we believe that Co₃O₄@CeO₂ hybrid flower-like microspheres with high peroxidase-like activity can be exploited for biosensing applications.

Multifunctional porous NiCo2O4 nanorods: sensitive enzymeless glucose detection and supercapacitor properties with impedance spectroscopic investigations

Multifunctional NiCo₂O₄ nanorods fabricated by a simple two-step method exhibit excellent performance in glucose sensors as well as supercapacitors.

Ce-based metal-organic frameworks and DNAzyme-assisted recycling as dual signal amplifiers for sensitive electrochemical detection of lipopolysaccharide

In this work, a sensitive electrochemical aptasensor was designed for lipopolysaccharide (LPS) detection based on Ce-based metal-organic frameworks (Ce-MOFs) and Zn(2+) dependent DNAzyme-assisted recycling as dual signal amplifiers. Herein, Ce-MOFs were decorated with gold nanoparticles (AuNPs) to obtain AuNPs/Ce-MOFs, and the resultant AuNPs/Ce-MOFs not only acted as nanocarriers to capture -SH terminated hairpin probes 2 (HP2) for acquiring HP2/AuNPs/Ce-MOFs signal probes, but also as catalysts to catalyze the oxidation of ascorbic acid (AA). In the presence of target LPS, report DNA was released from the prepared duplex DNA and then hybridized with hairpin probes 1 (HP1, which were immobilized on the electrode). With the help of Zn(2+), report DNA could act as Zn(2+) dependent DNAzyme to cleave HP1 circularly. Then a large amount of capture probes were produced on the electrode to combine with HP2/AuNPs/Ce-MOFs signal probes. When the detection solution contained electrochemical substrate of AA, AuNPs/Ce-MOFs could oxide AA to obtain enhanced signal. Under the optimized conditions, this proposed aptasensor for LPS exhibited a low detection limit of 3.3 fg/mL with a wide linear range from 10fg/mL to 100ng/mL.

One pot synthesis of CeO2 nanoparticles on a carbon surface for the practical determination of paracetamol content in real samples

Sucrose derived carbon decorated with CeO₂ nanoparticles (CeO₂–C) was prepared using a one pot synthesis and used for the electrochemical sensing of paracetamol.