Introduction

The invention consists of a photoanode for the generation of hydrogen by photocatalytic water splitting, thus addressing the challenge of finding new renewable, clean and storable energy sources. The electrode is composed by a nanostructured InGaN/InN layer directly grown on a commercially available silicon substrate, thus resulting in a device that is stable against degradation, environmentally friendly and cost effective.

Technical features

The invention relates to the generation of hydrogen by water splitting driven by solar energy. The aim of the present invention is to provide both a photoanode that does not undergo rapid degradation of photocatalytic efficiency, and a method for producing such photoanode on conventional Si photovoltaic cells while retaining the high activity required for the intended application. These and other objects are achieved with the present invention, which consists of a novel hybrid device integrating a photoanode on a commercial Si photovoltaic cell. The photoanode is made of an InGaN layer epitaxially grown on (111) crystallographic planes of p-type silicon and decorated by InN quantum dots. The InGaN layer provides a wide bandgap tunability for optimal absorption of solar radiation. The InN dots enhance the photocatalytic efficiency by increasing the positively charged surface donor states. The Si photovoltaic cell, easily providing the bias of 0.4 V, allows the integrated system to reach the 22% efficiency in solar energy conversion, in a fully autonomous system. This performance meets all the targets set by the US Department of Energy.

Possible Applications

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

Advantages

• Chemical stability;
• Wide bandgap tunability;
• Zero impact storable H2 production;
• Possible implementation on Silicon photovoltaic cells;
• Cost effective;
• Biological compatibility.