Carbon aerogels with nickel@N-doped carbon core-shell nanoclusters as electrochemical sensors for simultaneous determination of hydroquinone and catechol

Rational design of carbon nanomaterials with high adsorption capability and remarkable catalytic activity is essential to achieve high-performance sensors. In this paper, supramolecular hydrogels cross-linking of Ni2+, chitosan (CS) and multi-walled carbon nanotubes (MWCNT) are prepared and used as the precursors to produce nanocomposites composed of core-shell structures and carbon aerogels (denoted as NCACNT/Ni) by facile pyrolysis. Due to the anchoring of abundant functional groups on the CS chains and the spatial confinement of MWCNTs, the N-doped carbon shells encapsulating Ni nanoclusters with the small size of ca. 4 nm uniformly distribute in the carbon aerogels. On one hand, the N atoms on the shell accepting electrons from Ni cores can easily adsorb hydroquinone and catechol (HQ and CT) by hydrogen bonding to enhance the local molecular concentration; on the other hand, the highly active NiNx sites can enhance the oxide current response signal. The high adsorption capability and remarkable catalytic activity endow the NCACNT/Ni with high performance towards qualitative and quantitative determination of HQ and CT with a linear range from 2 to 100 μM and respective limit of detection (LODs) of 0.36 μM (3σ/k) and 0.41 μM (3σ/k). This work paves a new pathway for the rational design and engineering of carbon nanomaterials for electrochemical sensors and environmental analyses.