Atomic Sandwiched p-n Homojunctions.

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Semiconductor p-n junctions are crucial for photoelectrochemical (PEC) water splitting.
• Challenges include carrier recombination and slow oxygen evolution reaction (OER) kinetics in current designs.
• Advancements in p-n junction photoelectrode engineering are needed to improve water splitting efficiency.

Purpose of the Study:

• To engineer advanced p-n homojunctions in tin disulfide (SnS2) for enhanced PEC water splitting.
• To investigate the impact of nitrogen doping on SnS2 photoelectrode performance.
• To achieve efficient and stable solar water splitting for hydrogen and oxygen production.

Main Methods:

• Fabrication of three-unit-cell n-type SnS2 (n-SnS2) nanosheet arrays.
• Introduction of nitrogen (N) as acceptor dopants via controllable NH3 treatment to create sandwiched p-n homojunctions.
• Characterization of the N-doped pnp-SnS2 structure and evaluation of its PEC water splitting performance.

Main Results:

• The optimal N-doped pnp-SnS2 achieved a record photocurrent density of 3.28 mA cm⁻², a 21-fold increase over undoped n-SnS2.
• This represents the highest performance reported for SnS2 photoanodes in PEC water splitting.
• Stoichiometric O2 and H2 evolution with near 100% Faradaic efficiencies were observed.

Conclusions:

• The engineered sandwiched p-n homojunctions in N-doped SnS2 significantly enhance PEC water splitting.
• Improved performance is attributed to facilitated charge separation, accelerated OER kinetics, prolonged carrier lifetime, and enhanced stability.
• This work offers a promising strategy for developing high-performance photoelectrodes for solar fuel production.