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

Abstract 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 3d¹ electrons on the Ti³⁺ sites. In stark contrast to titanium dioxide (TiO₂), Ti₂O₃ has an ultra‐narrow bandgap (≈0.1 eV) at room temperature, resulting from strong correlation among the 3d¹ 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.