Tuning the surface Fermi level on p-type gallium nitride nanowires for efficient overall water splitting.
Solar water splitting is one of the key steps in artificial photosynthesis for future carbon-neutral, storable and sustainable source of energy. Here we show that one of the major obstacles for achieving efficient and stable overall water splitting over the emerging nanostructured photocatalyst is directly related to the uncontrolled surface charge properties. By tuning the Fermi level on the nonpolar surfaces of gallium nitride nanowire arrays, we demonstrate that the quantum efficiency can be enhanced by more than two orders of magnitude. The internal quantum efficiency and activity on p-type gallium nitride nanowires can reach ~51% and ~4.0 mol hydrogen h(-1) g(-1), respectively. The nanowires remain virtually unchanged after over 50,000 μmol gas (hydrogen and oxygen) is produced, which is more than 10,000 times the amount of photocatalyst itself (~4.6 μmol). The essential role of Fermi-level tuning in balancing redox reactions and in enhancing the efficiency and stability is also elucidated.
Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Québec, Canada H3A 0E9.
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Kibria
Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Québec, Canada H3A 0E9.
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Zhao
Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Québec, Canada H3A 0E9.
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Chowdhury
Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Québec, Canada H3A 0E9.
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Wang
Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Québec, Canada H3A 0E9.
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Nguyen
Science des Matériaux, IREQ, Hydro-Québec, 1800 Boulevard Lionel-Boulet, Varennes, Québec, Canada J3X1S1.
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Trudeau
Centre for the Physics of Materials, Department of Physics, McGill University, 3600 University Street, Montreal, Québec, Canada H3A 2T8.
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Guo
Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Québec, Canada H3A 0E9.
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D002384:Catalysis; D005708:Gallium / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D036103:Nanotechnology / Q000379:methods*; D053770:Nanowires / Q000737:chemistry*; D010084:Oxidation-Reduction; D010777:Photochemistry / Q000379:methods*; D056951:Photoelectron Spectroscopy; D011789:Quantum Theory; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
D014867:Water; C473348:gallium nitride; D005708:Gallium