Enhanced As(III) detection under near-neutral conditions: Synergistic effect of boosted adsorption by oxygen vacancies and valence cycle over activated Au NPs loaded on FeCoOx nanosheets

It is reported that As(III) has always been detected in acidic environments. Nevertheless, the unstable modified nanomaterials under strong acidic conditions may lead to unreliable results. Herein, an innovative method is proposed to employ FeCoOx nanosheets with abundant oxygen vacancies to stabilize even activate Au NPs for enhancing As(III) detection under mild conditions synergistically. Specifically, the sensitivity of 1.45 mu A ppb-1 with a detection limit (3 sigma method) of 0.27 ppb were obtained, which displays a promising application in the field of electrochemical detection. Moreover, the suggested electrode represented stable detection for As(III) in re-petitive measurements (RSD=2.60%, n = 10), and the ideal anti-interference performance was demonstrated. It's revealed that FeCoOx nanosheets with extensive interfacial area and the introduced oxygen vacancies afforded plentiful active sites for As(III) adsorption as well as assisted to stabilize Au NPs for uniform dispersion. Meanwhile, the valence cycle activated Au NPs and accelerated the transfer of electrons, which further synergies to boost the electro-catalysis of As(III). This study is not only favorable for understanding the positive facilitation of oxygen vacancies and the valence cycle of transition metals on catalytic performance; but also gives guidelines for constructing a novel electrochemical sensing interface.

Automated summary

This study proposes an innovative method for enhancing the detection sensitivity of As(III) by employing FeCoOx nanosheets to stabilize and activate Au NPs under mild conditions. The FeCoOx nanosheets with abundant oxygen vacancies provide active sites for As(III) adsorption and assist in stabilizing Au NPs for uniform dispersion. The valence cycle activated Au NPs and accelerated electron transfer, synergistically enhancing the electro-catalysis of As(III).