Hydrothermal synthesis of ternary α-Fe2O3-ZnO-Au nanocomposites with high gas-sensing performance

This study reports facile hydrothermal strategies for the synthesis of novel ternary alpha-Fe2O3-ZnO-Au nanocomposites under mild conditions, through further surface coating of ZnO and Au nanoparticles (NPs) on alpha-Fe2O3 nanorods. The ternary alpha-Fe2O3-ZnO-Au nanocomposites are found to show (1) higher sensitivity/responses (S) of 113 and 57 toward 100-ppm n-butanol and acetone, respectively compared to single alpha-Fe2O3 (S = 11.7, 9.1 for n-butanol, acetone) and binary alpha-Fe2O3-ZnO (S = 54.4, 28 for n-butanol, acetone) sensing materials, and (2) lower optimum operating temperature, i.e., 225 degrees C. The enhanced sensitivity could be attributed to the chemical sensitization effect induced by the Au NPs, and the existence of conjugated depletion layers in the nanocomposites which promote a greater drop in resistance upon exposure to the gas. These results will be useful for future design of iron oxide-based ternary nanocomposites as gas-sensing materials with high sensitivity, selectivity and stability. (C) 2014 Elsevier B.V. All rights reserved.