High Light Absorption and Charge Separation Efficiency at Low Applied Voltage from Sb-Doped SnO₂/BiVO₄ Core/Shell Nanorod-Array Photoanodes

Abstract

BiVO4 has become the top-performing semiconductor among photoanodes for photoelectrochemical water oxidation. However, BiVO4 photoanodes are still limited to a fraction of the theoretically possible photocurrent at low applied voltages because of modest charge transport properties and a trade-off between light absorption and charge separation efficiencies. Here, we investigate photoanodes composed of thin layers of BiVO4 coated onto Sb-doped SnO2 (Sb:SnO2) nanorod-arrays (Sb:SnO2/BiVO4 NRAs) and demonstrate a high value for the product of light absorption and charge separation efficiencies (ηabs × ηsep) of ∼51% at an applied voltage of 0.6 V versus the reversible hydrogen electrode, as determined by integration of the quantum efficiency over the standard AM 1.5G spectrum. To the best of our knowledge, this is one of the highest ηabs × ηsep efficiencies achieved to date at this voltage for nanowire-core/BiVO4-shell photoanodes. Moreover, although WO3 has recently been extensively studied as a core nanowire material for core/shell BiVO4 photoanodes, the Sb:SnO2/BiVO4 NRAs generate larger photocurrents, especially at low applied voltages. In addition, we present control experiments on planar Sb:SnO2/BiVO4 and WO3/BiVO4 heterojunctions, which indicate that Sb:SnO2 is more favorable as a core material. These results indicate that integration of Sb:SnO2 nanorod cores with other successful strategies such as doping and coating with oxygen evolution catalysts can move the performance of BiVO4 and related semiconductors closer to their theoretical potential.

Niobium Doping in BiVO4: Interplay Between Effective Mass, Stability, and Pressure

“…Poor transport of photo-induced carriers, electron-hole recombination and slow reaction kinetics at the interface are the crucial limitations of pristine BiVO 4 . [11][12][13] So far, many experimental techniques developed to synthesize BiVO 4 . The materials quality and stability depend on the experimental environment and routs to synthesize the material.…”

“…In fact, doping with appropriate ions and synthesizing it in a corresponding tuned chemical environment is one of the good strategies to overcome the limitations and hence enhancing the photocatalytic properties of BiVO 4 . There have been both experimental and theoretical works of BiVO 4 in the presence of defects and impurities [12,[14][15][16][17][18][19] to understand such strategies. Theoretical predictions of such strategies and growth environment for the desired dopant in BiVO 4 can be an important tool to expedite the search process.…”

Enhancing Mo:BiVO4 Solar Water Splitting with Patterned Au Nanospheres by Plasmon‐Induced Energy Transfer

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PEC cells demands the development of stable, economical, and efficient photoanodes. [4][5][6] One common strategy for improving these metal oxide photoanodes is to decorate them with various plasmonic metals, such as metal nanoparticles or nanorods, to introduce nearfield localized surface plasmon resonance (LSPR) and/or surface plasmon polaritons (SPP). [2,3] However, these metal oxide photoanodes exhibit poor efficiency because they cannot achieve simultaneously high light absorption, charge separation, and charge transfer efficiencies.

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Balancing Light Absorption and Charge Transport in Vertical SnS2 Nanoflake Photoanodes with Stepped Layers and Large Intrinsic Mobility

“…[42] As shown in Figure 4a, an LHE of about 90% was achieved at shorter wavelengths with absorption onset at around 580 nm. The LHE of our optimized nanoflakes was measured using an integrating sphere, as described in our previous report.…”