Recent Progress on Titanium Sesquioxide: Fabrication, Properties, and Applications

Titanium sesquioxide (Ti2O3) is drawing broad attention due to its fascinating physical properties and promising applications in the fields of energy, biomedicine, and electronics, among others. Its richness is due mainly to the strongly correlated 3d(1) electrons on the Ti3+ sites. In stark contrast to titanium dioxide (TiO2), Ti2O3 has an ultra-narrow bandgap (approximate to 0.1 eV) at room temperature, resulting from strong correlation among the 3d(1) electrons. Distinct electrical and optical properties are introduced in Ti2O3, accompanied with varied intriguing applications. Remarkable photothermal conversion, infrared photodetection, and electrocatalytic properties have been reported and explored in the past few years. Based on its unique and excellent properties, Ti2O3 has been utilized in seawater desalination, electrocatalytic water splitting, cancer therapy, hydrogen production, mid-infrared photodetection, nitrogen fixation, Li-ion batteries, etc. Herein, the fabrication, structural and electronic properties of Ti2O3 are comprehensively introduced, with a focused summary of recent research progress on its applications. Finally, current challenges, opportunities, and future perspectives of Ti2O3 are discussed.