WO3 is a promising candidate to be used as the photoanode material for photoelectrochemical (PEC) cell applications. However, chemical dissolution induced by OH-species in the solution rapidly degrades its photocatalytic activity, rendering it unfit for commercial applications. With the aim of improving its photostability, as well as enhancing the photocurrent for a high performance photoanode, we take the strategy of applying a thin layer of TiO2 as protection between the WO3 and the electrolyte. Our study first confirmed the fast degradation and gradual photoactivity loss of WO3 in solutions with pH greater than 5. After applying the protective layer, the stability of WO3 / TiO2 has significantly improved in comparison with bare WO3. Furthermore, the TiO2 / WO3 configuration forms a tandem photoanode exhibiting an increased photocurrent and light harvesting efficiency. We believe the increase in photocurrent is due to favorable band alignment of the two semiconductors, leading to enhanced charge separation. Further improvement in the light harvest is also demonstrated by creating nanostructured WO3 thin films.

WO3-based tandem photoanode with improved stability and photoelectrochemical efficiency

248th National Meeting (2014)

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