TY - JOUR AU - Francesca M Toma AU - Jason K Cooper AU - Viktoria Kunzelmann AU - Matthew T McDowell AU - Jie Yu AU - David M Larson AU - Nicholas J Borys AU - Christine Abelyan AU - Jeffrey W Beeman AU - Kin Man Yu AU - Jinhui Yang AU - Le Chen AU - Matthew R Shaner AU - Joshua Spurgeon AU - Frances A Houle AU - Kristin A Persson AU - Ian D Sharp AB -

Artificial photosynthesis relies on the availability of semiconductors that are chemically stable and can efficiently capture solar energy. Although metal oxide semiconductors have been investigated for their promise to resist oxidative attack, materials in this class can suffer from chemical and photochemical instability. Here we present a methodology for evaluating corrosion mechanisms and apply it to bismuth vanadate, a state-of-the-art photoanode. Analysis of changing morphology and composition under solar water splitting conditions reveals chemical instabilities that are not predicted from thermodynamic considerations of stable solid oxide phases, as represented by the Pourbaix diagram for the system. Computational modelling indicates that photoexcited charge carriers accumulated at the surface destabilize the lattice, and that self-passivation by formation of a chemically stable surface phase is kinetically hindered. Although chemical stability of metal oxides cannot be assumed, insight into corrosion mechanisms aids development of protection strategies and discovery of semiconductors with improved stability.

BT - Nature Communications DA - 05/2016 DO - 10.1038/ncomms12012 IS - 1 LA - eng N2 -

Artificial photosynthesis relies on the availability of semiconductors that are chemically stable and can efficiently capture solar energy. Although metal oxide semiconductors have been investigated for their promise to resist oxidative attack, materials in this class can suffer from chemical and photochemical instability. Here we present a methodology for evaluating corrosion mechanisms and apply it to bismuth vanadate, a state-of-the-art photoanode. Analysis of changing morphology and composition under solar water splitting conditions reveals chemical instabilities that are not predicted from thermodynamic considerations of stable solid oxide phases, as represented by the Pourbaix diagram for the system. Computational modelling indicates that photoexcited charge carriers accumulated at the surface destabilize the lattice, and that self-passivation by formation of a chemically stable surface phase is kinetically hindered. Although chemical stability of metal oxides cannot be assumed, insight into corrosion mechanisms aids development of protection strategies and discovery of semiconductors with improved stability.

PY - 2016 ST - Nat Commun T2 - Nature Communications TI - Mechanistic insights into chemical and photochemical transformations of bismuth vanadate photoanodes VL - 7 ER -