Efficient and stable visible-light-driven Z-scheme overall water splitting using an oxysulfide H₂ evolution...

Area of Science:

• Photocatalysis
• Materials Science
• Renewable Energy

Background:

• Z-scheme systems enable overall water splitting using narrow-bandgap photocatalysts.
• Enhancing photocatalyst activity, electron transfer, and suppressing back reactions are crucial for system performance.
• Sm2Ti2O5S2 is a novel oxysulfide material with potential for photocatalytic applications.

Purpose of the Study:

• To develop a high-performance oxysulfide photocatalyst for Z-scheme overall water splitting.
• To investigate the efficiency and stability of a Sm2Ti2O5S2/BiVO4/reduced graphene oxide system.
• To evaluate the system's performance under varying pressure conditions relevant to practical applications.

Main Methods:

• Synthesis and surface modification of Sm2Ti2O5S2 as a hydrogen evolution photocatalyst.
• Integration of Sm2Ti2O5S2 with BiVO4 (oxygen evolution photocatalyst) and reduced graphene oxide (electron mediator).
• Testing of the Z-scheme system for overall water splitting, measuring solar-to-hydrogen efficiency and stability over 100 hours.
• Evaluation of system activity under elevated background pressure (up to 90 kPa).

Main Results:

• The developed Z-scheme system achieved a solar-to-hydrogen energy conversion efficiency of 0.22%.
• The system demonstrated stable water splitting activity for over 100 hours.
• Water splitting performance was minimally affected by increasing background pressure to 90 kPa, indicating robustness.

Conclusions:

• The novel Sm2Ti2O5S2 oxysulfide photocatalyst is effective for Z-scheme overall water splitting.
• The integrated system shows high stability and efficiency, suitable for practical conditions.
• The system's resilience to pressure variations highlights its potential for real-world hydrogen production.