Science Daily April 5, 2021
Development of an efficient and durable photoelectrode is important for the deployment of solar-fuel production. A team of researchers in the US (Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, University of Michigan) has shown the photoelectrochemically self-improving behaviour of a silicon/gallium nitride photocathode for hydrogen production with efficiency approaching ~100%. Using correlative approach based on different spectroscopic and microscopic techniques, and density functional theory calculations, they provided a mechanistic understanding of the chemical transformation as the origin of the self-improving behaviour. A thin layer of gallium oxynitride forms on the side walls of the gallium nitride grains, via a partial oxygen substitution at nitrogen sites, and displays a higher density of catalytic sites for the hydrogen-evolving reaction. The chemical transformation of gallium nitride into gallium oxynitride leads to sustained operation and enhanced catalytic activity, thus showing promise for oxynitride layers as protective catalytic coatings for hydrogen evolution. The work could accelerate the commercialization of artificial photosynthesis technologies and hydrogen fuel cells…read more. TECHNICAL ARTICLEÂ
Self-improving behaviour of Si/GaN photocathodes. Credit: Nature Materials (2021)Â