Technology Overview

Solar produced hydrogen is a clean and storable source of energy. Here we present a novel InGaN/InN quantum dot photo-anode that can promote direct conversion of solar radiation into zero-impact hydrogen, via a process of photocatalytic water splitting, where the electrode is composed of a nanostructured InGaN/InN layer directly grown on a commercially available silicon (Si) substrate. The technology is cost effective and can be implemented into commercial Si solar cells. The electrode exhibits high resistance to degradation and thanks to the addition of InN quantum dots can lead to almost 10% efficiency without the aid of an external bias.

Technology Features, Specifications and Advantages

This InGaN/InN photo-anode promotes the direct conversion of white light into zero-impact hydrogen. The InGaN layer can be grown directly on economically viable Si substrates via Molecular Beam Epitaxy (MBE). InGaN exhibits high resistance to degradation and wide bandgap tunability, making it an optimal candidate for photocatalysis applications. The electrode is submerged in water and exposed to white light. The InGaN layer can absorb the optimal amount of solar radiation to promote the oxidation of water into O2 without any energy dispersion. The photocurrent generated inside the semiconductor drives the electrons to the working counter-electrode, on the surface of which H2 is produced. InN quantum dots can be grown in-situ directly on the InGaN surface via MBE. The quantum dots enhance the electrode efficiency by 50% compared to bare InGaN. InGaN/InN properties alone allow to drive photo-electrochemical water splitting with almost 10% efficiency without an external voltage or the addition of a co-catalyst that could reduce the radiation adsorption. The electrode can be directly integrated into a commercial solar cell to obtain a high stability and high efficiency autonomous system.

Advantages

• Promotes water-splitting without the aid of an external bias or expensive catalysts
• InGaN layer electronic properties can be tailored to optimize charge transport and radiation adsorption
• InGaN exhibits an excellent resistance to degradation compared to other semiconductors
• InN quantum dots enhance the efficiency of the electrode and can be grown in-situ, thus saving time and materials
• 100% carbon-free
• Economically viable
• Can be directly integrated into existing Si-based technology.

Potential Applications

The electrode can be developed onto flexible surfaces for easier introduction in standard or more complex photocatalytic systems.

Applications in:

• Hydrogen production;
• Renewable energy;
• Biosensors;
• Intermediate band solar cells;
• Analytical chemistry.

Customer Benefit

The product which forms the base of the business is an InN/InGaN quantum dot photo-anode for solar hydrogen generation by water splitting which can be integrated with a commercial Si photovoltaic cell to form a hybrid device with maximized efficiency. The plan is to produce the photo-anode and deliver it to established companies for full system fabrication. Future plans include:

• the integration of the photoelectrode with a commercial Si solar cell which can boost the efficiency of a fully autonomous system
• the transfer to mass production technologies like metal organic vapor phase epitaxy.

The technology can be developed onto wide or flexible surfaces and easily introduced as a photocatalytic stage into traditional systems where the catalytic bias is provided by external photovoltaic cells.