The conversion of solar energy into hydrogen fuel by splitting water into photoelectrochemical cells (PEC) is an appealing strategy to store energy and minimize the extensive use of fossil fuels. The key requirement for efficient water splitting is producing a large band bending (photovoltage) at the semiconductor to improve the separation of the photogenerated charge carriers. Therefore, an attractive method consists in creating internal electrical fields inside the PEC to render more favorable band bending for water splitting. Coupling ferroelectric materials exhibiting spontaneous polarization with visible light photoactive semiconductors can be a likely approach to getting higher photovoltage outputs. The spontaneous electric polarization tends to promote the desirable separation of photogenerated electron- hole pairs and can produce photovoltages higher than that obtained from a conventional p-n heterojunction. Herein, we demonstrate that a hole inversion layer induced by a ferroelectric Bi4V2O11 perovskite at the n-type BiVO4 interface creates a virtual p-n junction with high photovoltage, which is suitable for water splitting. The photovoltage output can be boosted by changing the polarization by doping the ferroelectric material with tungsten in order to produce the relatively large photovoltage of 1.39 V, decreasing the surface recombination and enhancing the photocurrent as much as 180%.

Cobalt-Prussian blue analogues are remarkable catalysts for the oxygen evolution reaction (water oxidation) under mild conditions such as neutral pH. Although there is extensive reports on literature about the application...

Monoclinic BiVO 4 is recognized as a promising photoanode for water oxidation, but its relatively wide bandgap energy (E g %2.5 eV) and poor charge transport limit the light absorption (η abs ) and charge separation (η sep ) efficiencies, thus resulting in low photocurrents. To solve these drawbacks, here the η abs  η sep product has been decoupled by combining W-doped BiVO 4 and V 2 O 5 rods (E g %2.1 eV) for simultaneously increasing the light harvesting and the charge separation in photoanodes under back-side illumination. In this strategy, V 2 O 5 rods maximize the light absorption and hole transport throughout the W-BiVO 4 film, making more holes to achieve the V 2 O 5 /W-BiVO 4 /H 2 O interface to trigger the water oxidation reaction with photocurrents as high as 6.6 mA cm À2 at 1.23 V RHE after 2 h reaction. Notably, under back-side illumination, the W-BiVO 4 /V 2 O 5 photoanode exhibited η abs  η sep of 74.5 and 93.0% at 0.5 and 1.23 V RHE , respectively, the highest values reported up to date for BiVO 4 -based photoelectrodes. This simple strategy brings us closer to develop efficient photoanodes for photoelectrochemical water splitting devices.

No abstract

No abstract