In the paper published in Analytical Chemistry(http://pubs.acs.org/journal/ancham), The study team jointly led by Prof. HUANG Xingjiu from Institute of Intelligent Machines, Hefei Institutes of Physical Science，Chinese Academy of Sciences, designed highly sensitive electrochemical detection of As(III) in drinking water by Co_0.6Fe_2.4O₄ nanocubes self-assembly monolayer.

Both decreasing the size of nanomaterials and introducing the surface defects can greatly improve the electrochemical detection performance due to the nanosized effect-induced specific electrochemical properties. However, nanocrystals generally suffer from the agglomeration because of the spontaneous reduction of the system surface energy, which results in blocking the active sites from reacting with target ions and severely reducing the electrochemical sensitivity.

In this work, ~14 nm Co_0.6Fe_2.4O₄ nanocubes with a high density surface defects are synthesized and then easily self-assembled on the surface of working electrode. The fabricated highly homogeneous sensing interface are successfully used to detect As(III) with a considerable sensitivity.

The high adsorption and the good redox activity of Co_0.6Fe_2.4O₄ nanocubes caused by the surface defects are strongly proved byX-ray photoelectron spectroscopy (XPS) and the addition of Fe(II) and Co(II) during the detection.

Owing to the existence of surface defects, Co_0.6Fe_2.4O₄ nanocubes exhibit the high adsorption to As(III) and the fast redox of As(III) which has been demonstrated by XPS. The increased stripping current ,as the addition of Fe(II) and Co(II), suggests that the mediation effect of Fe(II)/(III) and Co(II)/(III) cycles on the surface of nanocubes is benefit for As(III) analysis.

Furthermore, the monolayer perfectly overcomes the agglomeration of nanocrystals during electrode modification, ensuring the exposure of active surface area on nanocubes to the largest extent.

Mostly important, this approach of tunable distribution of the nanosized defective nanoparticles on electrode provides a new opportunity for modifying electrodes without agglomeration and keeping the active of surface defects.

This work was financially supported by the National Natural Science Foundation of China, the Youth project of National Natural Science Fund of China, the CAS Interdisciplinary Innovation Team and the CASHIPS Director’s Fund for financial support.

Figure  Fabrication of Co_0.6Fe_2.4O₄nanocubes self-assembly monolayer at water-air interface and the strategy for detection of As(III) based on As(III) adsorption and redox mediation with Fe(II)/Fe(III) and Co(II)/Co(III) cycles on the surface of Co_0.6Fe_2.4O₄nanocubes.(Image provided by LI Shanshan)

Article link: http://pubs.acs.org/doi/10.1021/acs.analchem.7b04025

Title: Noble Metal-FreeCo_0.6Fe_2.4O₄ Nanocubes Self-Assembly Monolayer for Highly Sensitive Electrochemical Detection of As(III) based on Surface Defects

Keywords: Co_0.6Fe_2.4O₄nanocubes; self-assembly monolayer; As(III); Electrochemistry

Contact:

Prof. HUANG Xingjiu, Ph. D

Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, China

Tel: 86-551-6559-1167

Email: xingjiuhuang@iim.ac.cn