Noble-Metal-Free Co_0.6Fe_2.4O₄ Nanocubes Self-Assembly Monolayer for Highly Sensitive Electrochemical Detection of As(III) Based on Surface Defects

Abstract

Nanocrystals generally suffer from agglomeration because of the spontaneous reduction of the system surface energy, resulting in blocking the active sites from reacting with target ions, and then severely reducing the electrochemical sensitivity. In this article, a highly ordered self-assembled monolayer array is successfully constructed using ∼14 nm CoFeO nanocubes uniformly and controllably distributed on the surface of a working electrode (glass carbon plate). The large area and high exposure of the surface defects on CoFeO nanocubes are clearly characterized by high-resolution transmission electron microscopy (HRTEM) and atomic-resolution high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Expectedly, a considerable sensitivity of 2.12 μA ppb and a low limit of detection of 0.093 ppb are achieved for As(III) detection on this highly homogeneous sensing interface; this excellent electroanalysis performance is even better than that of noble metals electrodes. Most importantly, this approach of uniformly distributing the small-sized defective nanoparticles on the electrode surface provides a new opportunity for modifying the electrodes, as well as the realization of their applications in the field of environmental electroanalysis for heavy metal ions.

Surface Fe(II)/Fe(III) Cycle Promoted Ultra-Highly Sensitive Electrochemical Sensing of Arsenic(III) with Dumbbell-Like Au/Fe3O4 Nanoparticles

“…As shown in Figure c, almost no XPS signal of As(0) could be observed under applying negative potential, it is believed that the redox of As­(III) does not occur on the surface of 400 nm Fe 3 O 4 nanoparticle because their poor conductivity. It is specially to point out that a pure carbon electrode is not good to reduce As­(III) to As(0) because of its chemically inert for As­(III) redox. , However, the excellent adsorption effect of 400 nm Fe 3 O 4 is used to concentrate more As­(III) from the solution and desorb/diffuse to the surface of bare SPCE, resulting in a higher electrochemical signal. , Reaction shows that the Fe­(III) on ∼10 nm Fe 3 O 4 will be reduced to Fe­(II) via electrons from SPCE. This completes the Fe­(II)/Fe­(III) cycle.…”

ZnFe2O4 Nanoparticles for Electrochemical Determination of Trace Hg(II), Pb(II), Cu(II), and Glucose

“…Iron-based metal oxides, as an excellent modified electrode material, recently have been widely investigated due to their high adsorption and detection ability for HMIs. − Compared with single iron-based oxides (Fe 3 O 4 and Fe 2 O 3 ), binary iron-based spinel oxides show excellent electrochemical detection performance for HMIs and glucose owing to the synergistic effect such as NiFe 2 O 4 , MnFe 2 O 4 , and CoFe 2 O 4 . − Among these binary iron based-spinel oxides, ZnFe 2 O 4 (ZFO) is widely used in the applications such as gas sensors, water treatment, electrocatalysis, photocatalytic, and lithium ion batteries due to its numerous advantages such as the vast band gap, outstanding chemical stability, and magnetic properties. According to relevant reports, ZFO is used for electrochemical detection for Pb­(II) and glucose. , However, ZFO is rarely used for the simultaneous detection of multiple HMIs and glucose because ZFO still suffers from difficult problems such as the agglomeration of inhomogeneous nanoparticles, low surface areas, and poor conductivity.…”

Fabricating Bifunctional Co−Al2O3@USY Catalyst via In‐Situ Growth Method for Mild Hydrodeoxygenation of Lignin to Naphthenes

“…Recently, metal catalysts based on layered double hydroxides (LDHs) have shown great potential in biomass conversion with good hydrogenation activity. [20] Based on the structural topotactic transformation of LDH materials upon calcination in a reductive atmosphere, the LDHs-derived supported metal nanoparticles possess the unique properties of high dispersion (resulting from the atomic-scale dispersion of metal cations) as well as high stability (described as the anchoring effect of the substrate). [21] In our previous work, Ni 2 P/Al 2 O 3 catalyst based on NiAl-LDH had demonstrated good activity.…”