This Feature summarizes recent works in paper-based potentiometry and voltammetry in heavy metal determination. Interactions of paper substrates with heavy metals, influence on the sensing response, and modification methods applied to paper substrates to improve the performance of recently developed electrochemical sensors are discussed. Since the rekindling of interest in paper-based analytical devices, methodologies and electrode designs for heavy metal determinations are highlighted. Promising aspects of the use of these sensors for samples containing solids and the increased versatility of the use of paper in analytics offers the possibility of increased acceptance of these low-cost platforms.

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Well‐defined, stoichiometric derivatives of graphene afford many opportunities in fine‐tuning of graphene properties and hence, extend the application potential of this material. Here, we present the electrochemical properties of cyanographene (G−CN), and graphene acid (G−COOH) in order to understand the role of the covalently attached functional groups on the graphene sheet in electrochemical sensing for the detection of biomarkers. G−CN shows better performance for the negatively charged analytes ascorbic and uric acids when compared to G−COOH. The less‐favourable performance of G−COOH is explained by repulsion between negatively charged analytes and negatively charged functional groups of G−COOH. The capacitance of both materials is in a comparable range, but chronopotentiometry reveals that G−CN shows a greater capacitance than G−COOH. The identified differences in electrochemical properties imprinted by the functional group show that its chemical nature can be exploited in fine‐tuning of the selectivity of electrochemical sensing and energy storage applications.

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