Photoelectrochemical water splitting on metal-nitride nanowire arrays: Breaking the efficiency bottleneck of solar-to-hydrogen conversion

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This project is related to the generation of green hydrogen using a clean, renewable process via photoelectrochemical water splitting under direct solar irradiation. Compared to solar electricity, the use of chemical bonds to store solar energy promises significantly reduced device fabrication cost, as well as the cost associated with energy storage. Over the past 40 years, researches have been largely focused upon metal-oxide based photocatalyst materials that are only responsive to ultraviolet (UV) light (~ 4% in solar spectrum). We have recently demonstrated, for the first time, spontaneous hydrogen production from pure water splitting on metal-nitride nanowires under blue and green-lighting irradiation (up to ~ 560 nm), the longest wavelength ever reported. We have further identified that the currently reported low solar-to-hydrogen conversion efficiency (~1-2%) on nanoscale photocatalysts is largely limited by Fermi-level pinning and surface band bending. In this project, by engineering the surface charge properties of metal-nitride nanowires through controlled Mg-dopant incorporation, we aim to enhance the solar-to-hydrogen conversion efficiency by one to two orders of magnitude. We will investigate the synthesis, characterization, and photocatalytic properties of multi-band InGaN:Mg nanowire arrays, that can break the efficiency bottleneck of solar-to-hydrogen conversion. We aim to demonstrate one-step solar-to-hydrogen production with an energy conversion efficiency of more than 15%, which is comparable to the efficiency of commercial solar cells. This project also involves close collaborations with research staff members in IREQ, Hydro-Québec and CIS Scientific Inc. in Montreal, who are in the business of developing clean energy devices and systems. We strongly believe it is of imminent interest to launch such a multidisciplinary project, which is poised to provide a paradigm shift in the rapidly evolving solar energy and hydrogen industries.