Nanocomposite Based Sensory Systems for the Planet-Mimic and other Extreme Environments

The planetary exploration has been one of the NASA’s focuses for decades.  Efforts have been achieved in the Lunar and Martian missions. Due to the currently changed situation, the attention has been shifted to the earth-like, planet-mimic, or other extraordinary environmental study.  Highlights of this on-ground mimic study include “reusable approaches” and “assays under extreme conditions” that will strengthen our understanding of the total Earth and similar planetary systems, and the effects of natural and human-induced changes on the global environment. In this work, we systematically developed and compared conventional, mesoscopic, and nanosized composites for their sensory application under extreme conditions. The compounds we chose are nickel, nickel oxide, and nickel hydroxide. Conventional chemical synthesis and in-situ surface preparation were both employed to get bulky and thin layer material respectively. While both protocols generated functional substances that exhibit sensory responses under very harsh conditions (high temperature, high pressure, and high alkalinity), the thin-layer approach resulted in the formation of nanocompsite films that can be operated in a more repeatable and more controllable fashion than others.  Nanosized nickel hydroxide thin films displayed excellent voltammetric responses toward some organic molecules including alcohols, aldehydes, sugars, starches, and amino acids that represent the model indicator compounds existed in different stages of the long, pre-history evolution. Our mechanistic study found the redox transition of Ni(II/III) moieties within the film mesoscopic networks are responsible for these responses.  The excellent reversibility of the redox transition makes the sensing events reproducible and stable.  The sensory study was carried out under extraordinary conditions that showed the great promise to be extended into an earth-like, planet-mimic environment, which adds new means to the existent analytical arsenal in the search of extraterrestrial life and planetary exploration. This work was supported by NASA-TSGC-NIP, SACP-UARP, Starter-award of UARP, and Welch Grant ( BJ-0027 ).