Surface-engineered mesoporous carbon-based material for the electrochemical detection of hexavalent chromium

Abstract

Detection of toxic hexavalent chromium in soil, groundwater, industrial effluent, etc., is of significant interest. We demonstrate the electrochemical detection of Cr(VI) using a surface-engineered mesoporous carbon-based material. The mesoporous carbon-based material is obtained by the controlled pyrolysis of a homogenous mixture of Fe and Co complexes of hydrolyzed collagen. The as-synthesized material is subjected to surface engineering by acid treatment. The surface-engineered mesoporous carbon-based material has a surface area as large as 443.28 m² g⁻¹ with interconnected mesopores. Detection of Cr(VI) was achieved at parts per billion level by electrochemical reduction using the surface-engineered carbon-based electrode at the potential of 0.65 V (Ag/AgCl). The modified electrode has excellent sensitivity (7.75 ± 0.03 × 10^-4 μA/ppb) and selectivity, low detection limit (8 ppb), and wide linear range (40–800 ppb). The coexisting other metal ions do not interfere with the amperometric measurement of Cr(VI). The electrode is highly stable and it retains >65% of the initial current during the long-term durability test for an hour. The highly porous nature of the material favors facile mass transport and facilitate electron transfer kinetics. The trace amount of CoFe alloy present in the carbon-based material catalyses the reduction of Cr(VI) at a favourable potential.