Quasi-1D hyperbranched WO3 nanostructures for low-voltage photoelectrochemical water splitting

Abstract

Arrays of hyperbranched high aspect ratio mesostructures are grown by pulsed laser deposition through a self-assembly process from the gas phase. These hierarchical arrays are successfully used as photoanodes for the photoelectrochemical splitting of water, exhibiting an onset potential as low as 0.4 V vs. RHE and saturation current densities up to 1.85 mA cm⁻² at 0.8 V vs. RHE. While the latter is similar to the state of the art values for WO₃ nanostructured photoanodes, both the onset and saturation voltages are significantly lower than any other reported values. This peculiar behavior is attributed to the hyperbranched structure and to its excellent optical and electronic properties.