Mn²⁺ Doping in In₂S₃ Increases Photoanodic Activity for Photoelectrochemical Water-Splitting

Area of Science:

• Materials Science
• Photochemistry
• Renewable Energy

Background:

• Photoelectrochemical (PEC) water-splitting is crucial for sustainable hydrogen (H2) generation.
• Indium sulfide (In2S3) is a visible light-active semiconductor with potential for PEC applications.
• Improving the efficiency of In2S3 in water splitting requires enhanced charge separation and transport.

Purpose of the Study:

• To investigate the effect of Mn2+ doping on the PEC activity of In2S3.
• To enhance the hydrogen generation efficiency of In2S3 through in-situ hydrothermal modification.
• To evaluate the performance of Mn-doped In2S3 in both freshwater and saline water environments.

Main Methods:

• In-situ hydrothermal synthesis of Mn-doped In2S3 (Mn-In2S3) nanosheets.
• Photoelectrochemical measurements to determine photocurrent density and separation efficiency.
• Mott-Schottky analysis and Ultraviolet Photoelectron Spectroscopy (UPS) to characterize electronic properties.

Main Results:

• Mn-In2S3 exhibited a photocurrent density of 4.49 mA/cm2 at 1.2 V vs RHE, a significant increase from In2S3 (3.18 mA/cm2).
• Charge separation efficiency improved by 1.58 times in Mn-In2S3 (51.2%) compared to In2S3 (32.4%).
• Mott-Schottky analysis revealed a 3.23-fold enhancement in carrier density for Mn-In2S3, and performance in saline water also improved.

Conclusions:

• Mn2+ doping effectively enhances the photoelectrochemical water-splitting performance of In2S3 by improving charge transport and reducing recombination.
• The modified band edge positions and narrowed band gap in Mn-In2S3 contribute to its superior activity.
• Mn-In2S3 demonstrates practical applicability for hydrogen generation, showing robust performance in saline water.