Anthraquinone modification of microporous carbide derived carbon films for on-chip micro-supercapacitors applications

•Carbide derived carbon (CDC) films were modified with anthraquinone (AQ) species.•Electrochemical grafting of AQ was achieved in microporous carbon for the first time.•0.88 × 10−10 mol cm−2 of AQ were grafted to 700 °C chlorinated on-chip CDC thin film.•The total capacitance of the micro-supercapacitor electrodes was doubled in 1 M KOH.•AQ grafting opens the way for an increase of CDC electrode capacitance

The modification of carbide derived carbon (CDC) thin film electrodes with anthraquinone (AQ) molecules was demonstrated by using pulsed chronoamperometry, in 0.1 M NEt4BF4/ACN solution of AQ diazonium derivative. The functionalization of CDC electrodes was only possible when a critical pore size is reached: only 2 nm pore diameter CDC can be grafted with AQ moieties, smaller pore size leading to a poorly functionalized electrode. High AQ surface coverage of 0.88 × 10−10 mol.cm−2 was determined using 2 nm pore size CDC. Despite a decrease in double layer capacitance value of about 10%, the total capacitance of the AQ-modified on-chip CDC electrodes was twice larger than that of pristine CDC film, leading to high total capacitance value of 44 mF.cm−2 (338 F.cm−3). The cyclability of the AQ-modified on-chip CDC electrode was also investigated. The faradic contribution of AQ grafted molecules progressively decreased during cycling and only 39% of the normalized capacity remained after 500 cycles; this decrease has been assigned to electrostatic repulsion of dianionic AQ confined in narrow micropores in the alkaline media.

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