Improved photoelectrochemical water splitting efficiency of nanoporous GaN photoanode

Nanoporous (NP) GaN was used as a photoanode during photoelectrochemical water splitting and its efficiency and stability were compared with those of planar GaN. The NP GaN showed larger photocurrent density under illumination, which indicated more hydrogen generation. The enhancement was higher for a large applied voltage where the water splitting process was limited by charge transfer between semiconductor and electrolyte. Photocurrents decreased with time during the water splitting; however, the photocurrent degradation was less severe for NP GaN. It was attributed to efficient hole transport from photoanode to electrolyte in NP GaN due to its large surface area.