Synthesis, characterization and properties of indium-doped manganese oxide molecular sieve sponges

Abstract

Indium-doped manganese oxide semiconducting substrates were synthesized under hydrothermal conditions of 250–270 °C for 4–10 days to generate nanowires or nanorods. Next, a facile resuspension/freeze-drying route was utilized to fabricate free-standing manganese oxide molecular sieve sponges through the auto-knitting of substrate materials. Compared with undoped manganese oxide substrates, indium doped manganese oxide substrates may generate two new FT-IR bands at 1090–1092 cm⁻¹ and 1026–1028 cm⁻¹, weaken most Raman bands (i.e., 183, 329, 390, 476, 519, and 580 cm⁻¹) except the band at around 640 cm⁻¹, boost the activity of electrocatalytic oxygen reduction over the carbon electrode surface, and enhance electrical conductivity by 3–23 times under synthetic conditions for indium doping. Moreover, the mechanical property of a sponge is positively correlated with the length of the substrate nanowires.