Chemically Cross-linked Conductive Network Hydrogel as Dual-Functional Layer Enabling Stable Solar Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Photoelectrochemical (PEC) water splitting is a key technology for solar-to-hydrogen conversion.
• Challenges include slow charge transfer and photocorrosion, limiting efficiency and durability.
• A need exists for advanced materials to overcome the activity-stability trade-off.

Purpose of the Study:

• To develop a highly conductive and stable 3D porous hydrogel network for PEC water splitting.
• To integrate this hydrogel with a dual-functional catalyst layer and metal oxide semiconductors.
• To enhance both the activity and long-term stability of photoanodes.

Main Methods:

• Synthesized a 3D hydrogel network by cross-linking polyaniline (PANI) and poly(acrylic acid) (PAA).
• Anchored metal ions to create a P(ANI-AA)-CoFe dual-functional layer chemically bonded to the hydrogel.
• Integrated the Gel-CoFe/NiO layer onto various semiconductor metal oxide (MO) arrays (TiO2, Fe2O3, WO3, BiVO4) to form photoanodes.

Main Results:

• The P(ANI-AA)-CoFe/NiO/BiVO4 photoanode achieved a high photocurrent density of 6.26 mA cm⁻² at 1.23 V vs RHE.
• A large-scale system demonstrated sustained photocurrent of 27 mA with 500 hours of operational stability at 1.1 V vs RHE.
• The 3D porous structure effectively suppressed photocorrosion and improved charge transport.

Conclusions:

• The rationally designed hydrogel-catalyst dual-network provides a universal paradigm for overcoming the activity-stability trade-off in PEC systems.
• This approach significantly enhances the performance and durability of solar-to-hydrogen conversion devices.
• The developed photoanodes outperform previously reported PEC systems in terms of stability and efficiency.