A hole inversion layer at the BiVO4/Bi4V2O11 interface produces a high tunable photovoltage for water splitting

Abstract

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%.

Pulsed Laser Deposition of Bismuth Vanadate Thin Films—The Effect of Oxygen Pressure on the Morphology, Composition, and Photoelectrochemical Performance

“…Notably, pristine FTO/BiVO 4 photoanodes (prepared under 0.1 mbar with removed V 2 O 5 ) generated a lower photocurrent than photoanodes consisting of the BiVO 4 @Bi 4 V 2 O 11 heterojunction. It has been already reported that such a system positively affects the photoelectroactivity in comparison to bare BiVO 4 [31,36]. The geometry of the system should be taken into account, as it was discussed for the BiVO 4 /V 2 O 5 photoanode.…”

“…The formation of heterojunction leads to the inhibition of bulk electron/hole recombination [38]. Generally, the presence of type-II heterojunction enhances bulk e − /h + separation efficiency due to the internal electric field generated on the phases interface, e.g., BiVO 4 /Bi 4 V 2 O 11 [36]. The enhancement of photoactivity in the case of the Bi 4 V 2 O 11 -containing photoanode may be also related to improved charge transfer resistance through the photoactive film in comparison with pristine BiVO 4 as it was reported previously [22].…”

Metal Chalcogenides on Silicon Photocathodes for Efficient Water Splitting: A Mini Overview

“…The illuminated open-circuit potential (OCP) is a feasible way for determining V fb when sufficient light is illuminated to remove band bending. This technique is an effective and convenient way to obtain the V ph of the electrode and gives useful information about the band bending and is commonly measured by increasing the light intensity until the J ph saturates [46]. Figure 7 depicts the OCP versus the illumination intensity to the samples of p-GaAsPN cell, MDMP-PPV:PCMB (bulk heterojunctions consisting of polyf2-methoxy-5-s38,78-dimethyloctyloxyd-pphenylenevinylene (MDMO-PPV) and 6,6-phenyl C61-butyric acid methyl ester PCBM), dye-sensitized solar cell (DSSC) (ITO/CuPc/C 60 /BPen/Al) and polycrystalline Si.…”

“…et al, who introduced an efficient approach which is coupling ferroelectric materials with semiconductors to boost the photovoltage higher than that obtainable from a conventional p-n heterojunction. The ferroelectric Bi 4 V 2 O 11 perovskite and n-type BiVO 4 creates a virtual p-n junction that produces high photovoltage of 1.39 V ( Figure 8j) [46]. The metal-insulator-semiconductor (MIS) photoanode using silicon was fabricated by Digdaya et al [57].…”

Enhancing Charge Separation in Photocatalysts with Internal Polar Electric Fields

“…Nanostructures of Bi 2 WO 6 , [77] Bi 2 MoO 6 , [78] Bi 2 O 2 CO 3 , [79] BiOX (X = Cl, Br,I ), [80][81][82] Bi 2 S 3 [83] and BiVO 4 [84] were synthesized as photocatalysts to decompose organic pollutants under visible-light irradiation. Although various methods, such as composite photocatalysts, noble metal loading and interfacial electric field, were used to improve the photocatalytic efficiency of bismuth-based photocatalysts, [84][85][86] the materials still demonstrate low quantum yields leadingt o www.chemphotochem.org low photocatalytic efficiencies. Therefore, buildinga ni nternal electric field in the crystal structure of photocatalystsi sa ne fficient strategy to greatlyi mprove charges eparationt oo btain materials with ahighq uantum yield.…”