Hydrothermal core–shell carbon nanoparticle films: thinning the shell leads to dramatic pH response

Physical Chemistry Chemical Physics Pub Date: 2012-10-11 DOI: 10.1039/C2CP42659E

Abstract

Carbon nanoparticles with phenylsulfonate negative surface functionality (Emperor 2000, Cabot Corp.) are coated with positive chitosan followed by hydrothermal carbonization to give highly pH-responsive core–shell nanocarbon composite materials. With optimised core–shell ratio (resulting in an average shell thickness of ca. 4 nm, estimated from SANS data) modified electrodes exhibit highly pH-sensitive resistance, capacitance, and Faradaic electron transfer responses (solution based, covalently bound, or hydrothermally embedded). A shell “double layer exclusion” mechanism is discussed to explain the observed pH switching effects. Based on this mechanism, a broader range of future applications of responsive core–shell nanoparticles are envisaged.

Graphical abstract: Hydrothermal core–shell carbon nanoparticle films: thinning the shell leads to dramatic pH response
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