Bimetallic iron–nickel sulfide nanowall arrays supported on nickel foam (Fe11.1%–Ni3S2/Ni foam) could efficiently drive both the overall water and urea electrolysis.

Transition metal-organic frameworks (MOFs), on account of their unique inherent properties of large pore volume, high specific surface area, tunable pores, and good catalytic activity, have been highly regarded as superior catalysts recently for water electrolysis, supercapacitors, batteries, sensors, and so on. Herein, we report on a cobalt MOF phase with 3D well-aligned nanosheets array architecture on carbon cloth (Co-MOF NS/CC), fabricated by a facile ambient liquid-phase deposition, could serve as a self-standing Janus catalytic electrode toward both glucose and water oxidation. It shows good glucose-sensing performance with low determination limit and large detection range. Also, it exhibits high water-oxidation efficiency with low overpotential and good durability. This work demonstrates the potential of utilizing transition-metal based well-aligned MOF nanoarrays for electrocatalytic oxidation.

Metal elements, including noble and transition metals, have always been required in the design of electrochemical sensors. Despite great advances, some drawbacks like the release of metal ions and exfoliation of catalysts from substrates still exist. Acid oxidation treatment, as a simple and effective way, is commonly used in the surface treatment of carbon materials, extensively used either directly as capacitive and catalytic electrodes or as the current collectors. However, its potential to be directly applied for electrochemical sensing has not been explored enough. In this work, a metal-free electrochemical sensor based on a surface oxygen-functionalized carbon cloth (CC) is fabricated through a simple acid oxidation treatment, during which more oxygen-containing groups are introduced, ensuring the solvent-accessible hydrophilic surface of electrodes and the improved surface interaction with dopamine. Our results suggest that the enhanced dopamine sensing performance can be obtained just through the introduction of oxygen-containing groups. Compared with raw CC, the acid-oxidized CC (AOCC) exhibits improved electrochemical sensing performance. A high sensitivity (9320 μA mM −1 cm −2 ), a low detection limit (10 nM), and a wide linear range (0.1−104.5 μM) are achieved. The selectivity, stability, and reproducibility are also proved to be satisfactory. Furthermore, the flexibility of AOCC endows its promising potential in fabricating wearable and soft electronics for human healthcare monitoring.

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