Biologically inspired catalyst for electrochemical reduction of hazardous hexavalent chromium.

An indirect electrochemical detoxification and detection platform has been demonstrated for toxic hexavalent chromium (Cr(vi)) based on the biologically important N-4 macrocycle. The research work describes a simple, green, low-cost and potential way for the synthesis of a new N-4 macrocyclic molecule and the molecule is characterized by various analytical and spectroscopic techniques like elemental analysis, TGA, FT-IR, UV-visible, mass spectrometry and NMR spectroscopies, and cyclic voltammetry. The synthesized molecule was explored for the electrochemical reduction of Cr(vi) using both voltammetric and amperometric methods. Amperometric studies exhibited 50 to 2500 nM linear range and the detection limit and quantification limit are 18 and 50 nM, respectively. The common coexisting metal ions did not interfere with Cr(vi) even in the presence of 40-fold excess interfering ions. The real sample analysis was carried out with the fabricated sensor and successfully quantified a recovery result (98-104%) of Cr(vi) in water. This proposed sensor is helpful in the detection of chromium ions in drinking water and is capable of detecting Cr(vi) in the limits set by the World Health Organization (WHO). In addition, this sensor satisfactorily demonstrated considerable stability and reproducibility.

Redox Active Binary Logic Gate Circuit for Homeland Security.

Bipolar junction transistors are at the frontiers of modern electronics owing to their discrete voltage regulated operational levels. Here we report a redox active binary logic gate (RLG) which can store a "0" and "1" with distinct operational levels, albeit without an external voltage stimuli. In the RLG, a shorted configuration of half-cell electrodes provided the logic low level and decoupled configuration relaxed the system to the logic high level due to self-charge injection into the redox active polymeric system. Galvanostatic intermittent titration and electrochemical quartz crystal microbalance studies indicate the kinetics of self-charge injection are quite faster and sustainable in polypyrrole based RLG, recovering more than 70% signal in just 14 s with minor signal reduction at the end of 10000 cycles. These remarkable properties of RLGs are extended to design a security sensor which can detect and count intruders in a locality with decent precision and switching speed.