A photovoltaic-electrolysis system with high solar-to-hydrogen efficiency under practical current densities

Area of Science:

• Renewable Energy Technologies
• Electrocatalysis
• Green Hydrogen Production

Background:

• Photovoltaic-alkaline water (PV-AW) electrolysis is promising for green hydrogen generation.
• Current PV-AW systems face limitations in solar-to-hydrogen (STH) conversion efficiency at practical current densities, hindering economic viability.
• Low efficiencies (<20%) and high costs impede large-scale adoption of PV-AW for hydrogen fuel.

Purpose of the Study:

• To design and develop a highly efficient photovoltaic-alkaline water (PV-AW) electrolysis system.
• To overcome the efficiency limitations of existing PV-AW systems for cost-effective green hydrogen production.
• To achieve high STH conversion efficiencies at practical current densities.

Main Methods:

• Development of a customized alkaline water (AW) electrolyzer integrated with a concentrator photovoltaic (CPV) receiver.
• Design of a novel anodic oxygen evolving catalyst based on an iron oxide/nickel (oxy)hydroxide (Fe2O3-NiO(OH)) composite.
• System integration and performance testing under relevant operating conditions.

Main Results:

• The customized AW electrolyzer demonstrated unprecedented catalytic performance, achieving 1 A cm-2 at 1.8 V.
• The system achieved a high solar-to-hydrogen (STH) conversion efficiency of up to 29.1% at large current densities.
• This efficiency surpasses all previously reported photovoltaic-electrolysis systems, indicating significant advancement.

Conclusions:

• The developed PV-AW system, featuring a novel catalyst and CPV integration, significantly enhances green hydrogen production efficiency.
• The high STH efficiency achieved addresses the economic barriers of current PV-AW technologies.
• This work paves the way for more economical and large-scale green hydrogen generation using solar energy.