Highly sensitive colorimetric detection of Cr (VI) in water through nano-confinement effect of CTAB-MoS2/rGO nanocomposites

Abstract

Cr (VI) can invade the human body through digestion, respiratory tract, skin, and mucous membrane; therefore, the detection of Cr (VI) in water has extreme environmental significance. In this study, the intercalated CTAB broadened the interspacing of the MoS2, ensured that the interlayer gap between S-Mo-S molecules was unblocked, and exposed more reactive sites. CTAB-MoS2 grows vertically on the fewer layers of reduced graphene oxide (rGO) and forms a nanowall structure through a C-S bond. The unique nanowall structure of CTAB-MoS2/rGO constitutes the nano-confinement space, and CTAB changes the surface electrical property of CTAB-MoS2/rGO nanocomposites. Cr (VI) ions were fixed on the surfaces of the composites by electrostatic attraction. Based on the nano-confinement and electrostatic attraction effect of CTAB-MoS2/rGO, the sensitive colorimetric detection of Cr (VI) was achieved, and the detection limit was 1.25 nM (S/N = 3). The catalytic activity conforms to the Lineweaver-Burk equation; the reaction velocity (Vmax) and Michaelis-Menton constant (Km) of CTAB-MoS2/rGO nanocomposites for Cr (VI) detection are 14.85 × 10−7 Ms−1 and 1.09 mM, respectively. The colorimetric sensing method not only has a high selectivity for the Cr (VI) but also can be utilized for the determination of Cr (VI) in real samples. Consequently, the colorimetric sensing method provides a broad range of environmental monitoring prospects.