N-type BiVO4 has recently emerged as a promising photoanode because it can generate up to J = 7.6 mA/cm2, utilizing a significant portion of visible light without needing much external bias, due to its favorable CB edge position near the thermodynamic H2 evolution potential.  However, the solar-to-hydrogen efficiency achieved by BiVO4 to date has been far below what is expected because it suffers from extremely low electron-hole separation yield (Fsep).  To date, the effort to improve Fsep of BiVO4 has mainly focused on doping studies, which intended to improve its poor electron transport properties.  In this presentation we report electrochemical synthesis of a nanoporous BiVO4 electrode with a specific surface area of 32.9 m2/g that effectively suppresses bulk carrier recombination without additional doping.  We will also discuss a new concept to interface BiVO4 with oxygen evolution catalysts (OECs), which enables the optimization of the BiVO4/OEC interface and the OEC/electrolyte interface simultaneously. The resulting photoanode generates a photocurrent density of 2.73 mA/cm2 for water oxidation at 0.6 V vs. RHE in a neutral phosphate buffer.

Nanoporous bismuth vanadate photoanodes for use in solar energy conversion

247th National Meeting (2014)

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