Amorphous Ni-P nanoparticles anchoring on nickel foam as an efficient integrated anode for glucose sensing and oxygen evolution

P-incorporated CuO/Cu2S heteronanorods as efficient electrocatalysts for the glucose oxidation reaction toward highly sensitive and selective glucose sensing

Currently, tremendous efforts have been made to explore efficient glucose oxidation electrocatalysts for enzymeless glucose sensors to meet the urgent demands for accurate and fast detection of glucose in the fields of health care and environmental monitoring. In this work, an advanced nanostructured material based on the well-aligned CuO/Cu2S heteronanorods incorporated with P atoms is successfully synthesized on a copper substrate. The as-synthesized material shows high catalytic behavior accompanied by outstanding electrical conductivity. This, combined with the unique morphology of unstacked nanorod arrays, which endow the entire material with a greater number of exposed active sites, make the proposed material act as a highly efficient electrocatalyst for the glucose oxidation reaction. Density functional theory calculations demonstrate that P doping endows P-doped CuO/Cu2S with excellent electrical conductivity and glucose adsorption capability, significantly improving its catalytic performance. As a result, a non-enzymatic glucose sensor fabricated based on our proposed material exhibits a broad linear detection range (0.02-8.2 mM) and a low detection limit (0.95 μM) with a high sensitivity of 2.68 mA mM-1 cm-2 and excellent selectivity.

A Facile Molecular Approach to Amorphous Nickel Pnictides and Their Reconstruction to Crystalline Potassium-Intercalated γ-NiOOHx Enabling High-Performance Electrocatalytic Water Oxidation and Selective Oxidation of 5-Hydroxymethylfurfural

The low-temperature molecular precursor approach can be beneficial to conventional solid-state methods, which require high temperatures and lead to relatively large crystalline particles. Herein, a novel, single-step, room-temperature preparation of amorphous nickel pnictide (NiE; EP, As) nanomaterials is reported, starting from NaOCE(dioxane)n and NiBr2 (thf)1.5 . During application for the oxygen evolution reaction (OER), the pnictide anions leach, and both materials fully reconstruct into nickel(III/IV) oxide phases (similar to γ-NiOOH) comprising edge-sharing (NiO6 ) layers with intercalated potassium ions and a d-spacing of 7.27 Å. Remarkably, the intercalated γ-NiOOHx phases are nanocrystalline, unlike the amorphous nickel pnictide precatalysts. This unconventional reconstruction is fast and complete, which is ascribed to the amorphous nature of the nanostructured NiE precatalysts. The obtained γ-NiOOHx can effectively catalyse the OER for 100 h at a high current density (400 mA cm-2 ) and achieves outstandingly high current densities (>600 mA cm-2 ) for the selective, value-added oxidation of 5-hydroxymethylfurfural (HMF). The NiP-derived γ-NiOOHx shows a higher activity for both processes due to more available active sites. It is anticipated that the herein developed, effective, room-temperature molecular synthesis of amorphous nickel pnictide nanomaterials can be applied to other functional transition-metal pnictides.

One-dimensional cobalt oxide nanotubes with rich defect for oxygen evolution reaction

For the electrochemcial hydrogen production, the oxygen evolution reaction (OER) is a pivotal half-reaction in water splitting. However, OER suffers sluggish kinetics and high overpotential, leading to the increase of overall energy consumption and decrease of the energy efficiency. In this work, high-quality cobalt oxide porous nanotubes (Co₃O₄-PNTs) are easily obtained by simple self-template approach. One-dimensional (1D) porous structure provides the large specific surface area, enough abundant active atoms and effective mass transfer. In addition, Co₃O₄-PNTs also own self-stability of 1D architecture, benefitting the their durability for electrocatalytic reaction. Thus, Co₃O₄-PNTs with optimal annealing temperature and time reveal the attractive alkaline OER performance (Tafel slope of 56 mV dec^-1and 323 mV overpotential at 10 mA cm^-2), which outperform the Co₃O₄nanoparticles and benchmark commercial RuO₂nanoparticles. Furthermore, Co₃O₄-PNTs also exhibit excellent OER durability for least 10 h at the 10 mA cm^-2. Overall, Co₃O₄-PNTs with low cost can be serve as a highly reactive and economical catalyst for OER.

Direct epitaxial growth of nickel phosphide nanosheets on nickel foam as self-support electrode for efficient non-enzymatic glucose sensing

Design and develop of cost-effective non-enzymatic electrode materials is of great importance for next generation of glucose sensors. In this work, we report a high-performance self-supporting electrode fabricated via direct epitaxial growth of nickel phosphide on Ni foam (Ni₂P/NF) for nonenzymatic glucose sensors in alkaline solution. Under the optimal conditions, the uniform Ni₂P nanosheets could be obtained with an average thickness of 80 nm, which provides sufficient active sites for glucose molecules. As a consequence, the Ni₂P/NF electrode displays superior electrochemistry performances with a high sensitivity of 6375.1μA mM^-1cm^-2, a quick response about 1 s, a low detection limit of 0.14μM (S/N = 3), and good selectivity and specificity. Benefit from the strong interaction between Ni₂P and NF, the Ni₂P/NF electrode is also highly stable for long-term applications. Furthermore, the Ni₂P/NF electrode is capable of analyzing glucose in human blood serum with satisfactory results, indicating that the Ni₂P/NF is a potential candidate for glucose sensing in real life.