Strategies for the deposition of LaFeO3 photocathodes: improving the photocurrent with a polymer template

Abstract

Renewable and sustainable alternatives to fossil fuels are needed to limit the impact of global warming. Using metal oxide semiconductors as photoelectrodes within photoelectrochemical cell devices, in which solar energy can be stored and ultimately used for electricity generation, is one such alternative. LaFeO₃ (LFO) has been shown to be an active photocathode in the illumination of visible light but is restricted by a low surface area and relatively low photocurrents achieved. The work herein utilizes a spin coating deposition method with a solution of nitrate precursors combined with a non-ionic polymeric surfactant (Triton X-100). This allowed for the formation of a uniform porous LFO film of high coverage on a fluorine-doped tin oxide-coated substrate by directing the growth and preventing particle aggregation during film fabrication. These porous LFO films achieved an enhanced photocurrent of −161 ± 6 μA cm⁻² at +0.43 V_RHE, in addition to a remarkably high onset potential of +1.4 V_RHE for cathodic photocurrent. It was additionally shown that the attained film quality and activity were superior to those of other film fabrication methods such as doctor blading and spray pyrolysis. With this polymer templating method for LFO films, not only are higher photocurrents achieved but there are also added benefits such as better charge separation, higher efficiencies, higher specific electrochemically active surface area, and improved stability.