Enhanced production rates of hydrogen generation and carbon dioxide reduction using aluminum gallium nitride/gallium nitride heteroepitaxial films as photoelectrodes in seawater

In this study, aluminum gallium nitride/gallium nitride heterostructure grown on the sapphire substrate is used as the photoanodes for the generation of hydrogen gas and formic acid through water photoelectrolysis and carbon dioxide reduction, respectively, in photoelectrochemical reaction. These processes are conducted using carbon dioxide-containing sodium chloride aqueous solution and seawater, as the electrolytes. The typical production rates of formic acid and hydrogen gas produced from photoanodes made of aluminum gallium nitride/gallium nitride heterostructure are significantly higher than those of photoanodes made of a single gallium nitride epitaxial layer. This enhancement in production rate is attributed to facilitated transport of photo generated electrons by two-dimensional electron gas at the aluminum gallium nitride/gallium nitride interface from the working area to the ohmic metal electrode on the photoelectrodes.