Template-cum-catalysis free synthesis of α-MnO2 nanorods-hierarchical MoS2 microspheres composite for ultra-sensitive and selective determination of nitrite

In this work, a novel composite constituted by alpha-MnO2 nanorods and hierarchical MoS2 microspheres is synthesized by a simple, template-cum-catalysis free two-step hydrothermal method for ultra-sensitive and selective detection of nitrite. The nitrite sensor (with optimal MnO2-MoS2 weight ratio) showed a limit of detection of 16 mu M, the short response time (<5 s), outstanding selectivity, reproducibility, and sensitivity of 515.84 mu A mM(-1) cm(-2) (R-2 = 0.996) in the range of 100-800 mu M in an optimized electrolytic pH of 4. The excellent sensing ability of the sensor can be attributed to the heterogeneous interface between two material constituents that results in unimpeded electrical transport due to the presence of intertwined nanosheets in MoS2 and 1D alpha-MnO2 nanorods, high number of active sites emanating from huge numbers of edges and defects in MoS2, high proportion of metallic (1T) phase than semiconducting (2H) phase in MoS2 and the combined effect of 1D alpha-MnO2 nanorods and MoS2 nanosheets. The fabricated sensor was also effectively assessed for the detection of nitrite in potable water. This novel, binderfree, MnO2-MoS2 composite based electrode material paves a new way for the development of simple, non-enzymatic and inexpensive electrochemical sensors for analytical applications. (c) 2019 Elsevier B.V. All rights reserved.