High-valence Mo(VI) derived from in-situ oxidized MoS2 nanosheets enables enhanced electrochemical responses for nitrite measurements

Abstract Semiconducting MoS2 obtained from the liquid-phase exfoliation is oxidized at the potentials higher than 0.65 V via applied electrochemical processes, and high-valence Mo(VI) are formed. The oxidized MoS2 exhibits comparable performance to the electrochemical oxidation of nitrite, promoting the construction of sensors based on the assembly of nanomaterials. The signal amplification mechanism is exploited, and enhanced sensing responses are confirmed considering the strong coupling effect of Mo(VI) to nitrite. In order to optimize the sensing performance, the measurement parameters including the pH of buffer solutions, scan rates, and modification conditions are discussed. The cyclic voltammetry and chronoamperometry are successfully employed, and the oxidized MoS2 performs satisfactory linear relationship to nitrite concentrations ranging from 1.0 μM to 386.0 μM, with the detection limit of 0.028 μM. The oxidation state and enhanced electrochemical responses of semiconducting MoS2 as well as the developed nitrite sensing strategy inspire emerging characteristics of layered nanostructures and achieve the high potential in practical environmental and food safety monitoring.