Sn²⁺-Induced In Situ Phase Modulation Enabling a Highly Active o-SnSe/h-NiSe/r-Ni₃Se₂ Multifunctional Heterostructure...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Small-molecule-assisted water splitting requires highly active sites and integrated photothermal/photoelectronic properties.
• Existing electrocatalysts face limitations in efficiency and energy conversion.

Purpose of the Study:

• To develop a novel Sn²⁺-initiated phase-modulation strategy for synthesizing a multifunctional heterostructure.
• To investigate the synergistic effects of photothermal and photoelectronic properties on urea oxidation reaction (UOR) and water splitting.

Main Methods:

• Facile synthesis of rhombohedral NiSe and Ni₃Se₂ precursor.
• In situ phase transition to hexagonal NiSe and generation of orthorhombic SnSe.
• Formation of the o-SnSe/h-NiSe/r-Ni₃Se₂ heterostructure.
• Theoretical calculations to understand reaction mechanisms and energy barriers.
• Electrochemical testing for UOR activity and water splitting performance.

Main Results:

• The synthesized o-SnSe/h-NiSe/r-Ni₃Se₂ heterostructure exhibits enhanced light harvesting and photothermal/photoelectronic functionalities.
• h-NiSe lowers the UOR energy barrier, while o-SnSe promotes urea adsorption and accelerates kinetics.
• Photoelectronic effect significantly increases charge-carrier density and lowers UOR activation energy.
• Exceptional UOR activity achieved, with current densities of 10, 500, and 1000 mA cm^-2 at low overpotentials (1.28, 1.34, 1.37 V).
• Urea-assisted water splitting electrolyzer using this material outperforms conventional HER||OER electrolyzers.

Conclusions:

• The Sn²⁺-initiated phase-modulation strategy is effective for creating advanced electrocatalysts.
• The synergistic photothermal and photoelectronic effects in o-SnSe/h-NiSe/r-Ni₃Se₂ significantly boost water splitting efficiency.
• This work presents a promising pathway for developing efficient and cost-effective energy conversion technologies.