Metastable Hexagonal In₂O₃ Nanofibers Templated from InOOH Nanofibers under Ambient Pressure

Abstract Single‐crystal, metastable, hexagonal In 2 O 3 (H‐In 2 O 3 ) nanofibers with an average diameter of 80 nm and length of up to several micrometers were synthesized on a large scale, for the first time under ambient pressure, by annealing InOOH nanofibers at 490 °C. The InOOH nanofibers were prepared by a controlled hydrolysis solvothermal reaction, using InCl 3 ·4H 2 O as the starting material and ether as the solvent, in the temperature range of 190–240 °C. The solvent has significant effects on the formation of the metastable phase and the morphology of the In 2 O 3 nanocrystals during the synthesis of the precursor InOOH. Room‐temperature optical absorption spectra of the hexagonal In 2 O 3 nanofibers showed strong absorption peak located at 325 nm (3.83 eV) with a slight blue‐shift compared with that of bulk In 2 O 3 (3.75 eV). The H‐In 2 O 3 nanofibers photoluminesce at room temperature with emission peaks at 378 nm, 398 nm, and 420 nm. The successful production of metastable hexagonal In 2 O 3 nanofibers in large scale under mild conditions could be of interest both for applications and fundamental studies.