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

Abstract

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.