Unassisted water splitting with 9.3% efficiency by a single quantum nanostructure photoelectrode

To split water and produce hydrogen by white light is an excellent solution for the storage and supply of clean and sustainable energy. Efficiency and stability are the key challenges for a successful exploitation. InGaN, evaluated against other semiconductors, metal oxides, carbon based - and organic materials has most suited intrinsic materials properties. Based on this optimum materials choice we report photoelectrochemical (PEC) hydrogen generation under white light illumination by an InGaN-based quantum nanostructure photoelectrode. No degradation occurs for operation over 10 h. Our novel concept, combining quantum nanostructure physics with electrochemistry and catalysis leads to almost 10% efficiency at zero external voltage. The efficiency rises above 25% at 0.2 V. This is unmatched for a single photoelectrode, representing the most advanced technology of low complexity. •We report photoelectrochemical hydrogen generation under white light illumination.•We used epitaxial grown InN-quantum dots on InGaN-nanowalls as a photoelectrode.•Our novel concept leads to almost 10% efficiency at zero external voltage.•The efficiency rises above 25% at 0.2 V.•The device shows good stability, no degradation occurs for operation over 10 h.