Reduced Graphene Oxide Conjugated Cu2O Nanowire Mesocrystals for High-Performance NO2 Gas Sensor
作者: Suzi Deng, Verawati Tjoa, Hai Ming fan*, Hui Ru Tan, Dean C. Sayle, Malini Olivo, Subodh Mhaisalkar, Jun Wei, Chorng Haur Sow * 期刊:J. Am. Chem. Soc.2012, 134, 4905-4917
摘
要:Reduced graphene oxide (rGO)-conjugated Cu2O nanowire mesocrystals were formed by nonclassical crystallization in the presence of GO and o-anisidine
under hydrothermal conditions. The resultant mesocrystals are comprised
of highly anisotropic nanowires as building blocks and possess a
distinct octahedral morphology with eight {111} equivalent crystal
faces. The mechanisms underlying the sequential formation of the
mesocrystals are as follows: first, GO-promoted agglomeration of
amorphous spherical Cu2O nanoparticles at the initial stage,
leading to the transition of growth mechanism from conventional
ion-by-ion growth to particle-mediated crystallization; second, the
evolution of the amorphous microspheres into hierarchical structure, and
finally to nanowire mesocrystals through mesoscale transformation,
where Ostwald ripening is responsible for the growth of the nanowire
building blocks; third, large-scale self-organization of the
mesocrystals and the reduction of GO (at high GO concentration) occur
simultaneously, resulting in an integrated hybrid architecture where
porous three-dimensional (3D) framework structures interspersed among
two-dimensional (2D) rGO sheets. Interestingly, “super-mesocrystals”
formed by 3D oriented attachment of mesocrystals are also formed judging
from the voided Sierpinski polyhedrons observed. Furthermore, the
interior nanowire architecture of these mesocrystals can be kinetically
controlled by careful variation of growth conditions. Owing to high
specific surface area and improved conductivity, the rGO-Cu2O mesocrystals achieved a higher sensitivity toward NO2 at room temperature, surpassing the performance of standalone systems of Cu2O nanowires networks and rGO sheets. The unique characteristics of rGO-Cu2O mesocrystal point to its promising applications in ultrasensitive environmental sensors.