Nanostructured Bi2Se3‑Decorated TiSe2 Pyramids on Ti Foil for Photoelectrochemical Water Splitting.

The interface of two-dimensional transition metal dichalcogenides hosts collective interactions between the electronic structures that tune the charge density wave (CDW) states and the photoelectrochemical (PEC) properties of heterostructures. This work reports the influence of the interface on the CDW and PEC of a sputtered Bi₂Se₃/TiSe₂ heterostructure on Ti metal foils. The hexagonal nanoflakes on the spiral-pyramid-like surface morphology of pristine TiSe₂ confirm the Bi₂Se₃ decoration on the TiSe₂ sample. The stoichiometric growth of TiSe₂ and Bi₂Se₃ was revealed from X-ray photoelectron spectroscopy and Raman spectroscopy. The temperature-dependent Raman spectroscopy demonstrates the evolution of E_g^CDW and A_1g^CDW optical phonon modes with increased CDW phase transition temperature for the Bi₂Se₃/TiSe₂ heterostructure. The enhancement of photoresponsive properties of the Bi₂Se₃/TiSe₂ heterostructure under a solar light intensity of 100 mW/cm² (AM = 1.5 G) in 0.5 M Na₂SO₄ electrolyte solution toward suitable water splitting was validated from the PEC measurements. This engineered heterostructure can pave the futuristic path to studying light-active electrodes with tunable CDW properties of pristine TiSe₂ and Bi₂Se₃/TiSe₂ heterostructures grown on flexible Ti substrates. [ABSTRACT FROM AUTHOR]