Visible light-driven pure water splitting by a nature-inspired organic semiconductor-based system

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Natural photosynthesis utilizes photosystems (PSII and PSI) for water splitting.
• Graphitic carbon nitride (g-C3N4) is a robust organic semiconductor with potential photocatalytic applications.

Purpose of the Study:

• To integrate g-C3N4 into a nature-inspired water splitting system.
• To develop parallel systems using g-C3N4 with BiVO4 and WO3 for overall water splitting under visible light.

Main Methods:

• Development of two parallel water splitting systems incorporating g-C3N4 with BiVO4 and WO3.
• Investigation of the influence of pH, redox mediator concentration, and photocatalyst mass ratio on gas evolution rates.

Main Results:

• Both systems achieved simultaneous hydrogen and oxygen evolution in an ideal 2:1 ratio.
• Stable and reproducible hydrogen and oxygen evolution rates of 36 and 18 μmol h⁻¹ g⁻¹, respectively, were maintained over 14 hours.
• Gas evolution rates were found to be dependent on pH, redox mediator concentration, and the mass ratio of the photocatalysts.

Conclusions:

• Graphitic carbon nitride (g-C3N4) functions as a robust, multifunctional photocatalyst for water splitting.
• The developed systems mimic natural photosynthesis and offer potential for scalable hydrogen production.
• g-C3N4 shows promise for integration into other energy conversion systems like photoelectrochemical (PEC) cells and coupled solar cells.