Single-crystalline α-Fe2O3 oblique nanoparallelepipeds: High-yield synthesis, growth mechanism and structure enhanced gas-sensing properties

Abstract

In this paper, single-crystalline α-Fe2O3 oblique nanoparallelepipeds are fabricated in high yield via a facile surfactant-free hydrothermal method, which involves oriented aggregation and Ostwald ripening. The obtained nanocrystals have exposed facets of {012}, {01-4} and {-210} with a rhombohedral α-Fe2O3 structure. The gas sensors based on the as-synthesized α-Fe2O3 nanostructures exhibit high sensitivity, short recovery time, and good reproducibility in ethanol and acetone. The superiority of the gas-sensing properties of the obtained nanostructures should be attributed to the surface structure of the nanocrystals. The as-prepared α-Fe2O3 nanocrystals are significant for exploiting their other applications in the future.

Fabrication of α-Fe2O3/g-C3N4 composites for cataluminescence sensing of H2S

“…As described in the work of Li et al, the obtained graphene/g-C 3 N 4 nanocomposites can promote the catalytic capacity by activation of molecular oxygen, while that was not found for either pristine g-C 3 N 4 or graphene alone [26]. It is widely acknowledged that hematite (␣-Fe 2 O 3 ), a significant n-type semiconductor, the most stable iron oxide under ambient conditions, has been extensively applied to gas sensors, catalysts, and pigments owning to its low cost, non-toxicity and high resistance to corrosion [29][30][31]. Bearing these in mind, we devoted efforts to depositing ␣-Fe 2 O 3 on the g-C 3 N 4 sheets to build a composite, which may provided additional sites for the interaction with reaction gas, in expectation for designing a better catalyst.…”

Novel Composites of α‐Fe2O3 Tetrakaidecahedron and Graphene Oxide as an Effective Photoelectrode with Enhanced Photocurrent Performances

“…Hematite (α-Fe 2 O 3 ) is considered as a very interesting semiconductor and better reproducibility for ethanol and acetone detection than commercial α-Fe 2 O 3 powders. [ 30 ] The superiority has been ascribed to the special surface structure of polyhedral nanocrystals. The application of α-Fe 2 O 3 polyhedron to photoelectrochemical fi eld has been extended.…”

Gas Sensors Based on <I>α</I>-Fe<SUB>2</SUB>O<SUB>3</SUB> Nanorods, Nanotubes and Nanocubes

“…Therefore, the "surface accessibility" is crucial for maintaining the high sensitivity of crystals. 31 The nanotubes are enclosed by two preferentially exposed planes with {010} and two planes with {001}; the nanorods are enclosed by six equivalent crystal planes with {110} and two equivalent planes with {001}; the nanocubes are enclosed by planes with {012}, {102}, and {−11-2}. 32 Therefore, the preferential exposed planes {010} for nanotubes maybe lead to enhancement of gas sensitivity.…”

“…nanostructures including nanocubes, 15 16 nanorods, [17][18][19] nanobelts, 20 21 nanotubes, [22][23][24] nanoflowers, 25 nanorings, 26 dendritic micro-pines, 27 and nanoparticles 28 have been prepared. A few gas sensors based on these nanostructures such as poly-crystal nanotubes, nanourchin, nanorods, poly-crystal nanobelts, oblique nanoparallelepipeds, and hollow spheres, [29][30][31] have been fabricated and showed good gas-sensing properties, but they mainly focused on preparation and gas sensitivity on ethanol of the nanostructures, lacking in comparative study on relativity of gas sensitivity to single-crystal nanostructures with different exposed facets. Here we selectively synthesized single-crystalline nanorods, nanotubes and nanocubes of -Fe 2 O 3 , and then fabricated them into chemiresistive gas sensors to evaluate the gas-sensing properties for ethanol, acetone, formaldehyde, and ammonia, and discovered enhancing gas-sensing performance to these gases of -Fe 2 O 3 nanotubes.…”