Improved Charge Carrier Dynamics by Unconventional Doping Strategy for BiVO₄ Photoanode

Area of Science:

• Materials Science
• Photocatalysis
• Semiconductor Physics

Background:

• Bismuth vanadate (BiVO4) is a promising photoanode material for solar fuel production.
• Poor charge separation due to sluggish charge transport and short diffusion length limits BiVO4 efficiency.

Purpose of the Study:

• To investigate the effect of acceptor doping on BiVO4 charge carrier dynamics.
• To enhance charge separation and improve the efficiency of BiVO4 photoanodes.

Main Methods:

• Unconventional acceptor doping strategy using Al3+ ions.
• Characterization of charge carrier concentration, diffusion length, and carrier lifetime.
• Photoelectrochemical measurements to determine photocurrent density.

Main Results:

• Al doping decreased carrier concentration but increased carrier diffusion length and lifetime.
• Optimized 0.5 at% Al-doped BiVO4 (Al:BVO_0.5) showed a ~3.5 and 2.6 order of magnitude increase in diffusion length and carrier lifetime, respectively.
• Achieved a photocurrent density of 3.02 mA cm-2 at 1.23 V_RHE under AM 1.5G illumination.

Conclusions:

• Acceptor doping is an effective strategy to enhance charge carrier dynamics in BiVO4.
• Al doping in BiVO4 widens the space charge layer, facilitating charge transport and separation.
• This work provides new insights into semiconductor physics and design principles for efficient photoanodes.