Photoelectrochemical and crystalline properties of a GaN photoelectrode loaded with α-Fe2O3 as cocatalyst.

Nitrides are of particular interest in energy applications given their suitability to photocatalytically generate H₂ from aqueous solutions. However, one of the drawbacks of nitrides is the decomposition they suffer when used in photoelectrochemical cells. Here, we report the improvement of the catalytic performance and chemical stability of a GaN electrode when it is decorated with Fe₂O₃ particles compared with an undecorated electrode. Our results show a higher reaction rate in the Fe₂O₃/GaN electrode, and that photocorrosion marks take more than 20 times longer to appear on it. We also characterized the crystalline properties of the Fe₂O₃ particles with transmission electron microscopy. The results show that the Fe₂O₃ particles keep an epitaxial relationship with GaN that follows the Fe₂O₃ { 0003 } | | GaN { 0001 } and Fe₂O₃ [ 11 2 ¯ 0 ] | | GaN [ 1 1 ¯ 00 ] symmetry constraints. We also characterized an Fe₂O₃ (thin film)/GaN electrode, however it did not present any catalytic improvement compared with a bare GaN electrode. The epitaxial relationship found between the Fe₂O₃ thin film and GaN exhibited the Fe₂O₃ { 11 2 ¯ 0 } | | GaN { 0002 } and Fe₂O₃ [ 3 3 ¯ 00 ] | | GaN [ 11 2 ¯ 0 ] symmetry constraints. [ABSTRACT FROM AUTHOR]