posted on 2020-03-05, 18:10authored byPriscilla
P. Peregrino, Marco R. Cavallari, Fernando J. Fonseca, Sanclayton G. C. Moreira, Maria José
A. Sales, Leonardo G. Paterno
This work unveils the roles played
by potato starch (ST) in the
immobilization, photochemical reduction, and gas sensitivity of graphene
oxide (GO) films. The ST/GO films are assembled layer by layer (LbL)
onto quartz substrates by establishing mutual hydrogen bonds that
drive a stepwise film growth, with equal amounts of materials being
adsorbed in each deposition cycle. Afterward, the films are photochemically
reduced with UV irradiation (254 nm), following a first-order kinetics
that proceeds much faster when GO is assembled along with ST instead
of a nonoxygenated polyelectrolyte, namely, poly(diallyl dimethylammonium)
hydrochloride (PDAC). Finally, the gas-sensing performance of ST/reduced
graphene oxide (RGO) and PDAC/RGO sensors fabricated via LbL atop
of gold interdigitated microelectrodes is evaluated at different relative
humidity levels and in different concentrations of ammonia, ethanol,
and acetone. In comparison to the PDAC/RGO sensor, the ones containing
ST are much more sensitive, especially when operating in a high-relative-humidity
environment. An array comprising these chemical sensors provides unique
electrical fingerprints for each of the investigated analytes and
is capable of discriminating and quantifying them in a wide range
of concentrations, from 10 to 1000 ppm.