A Conformal Carbon Nanolayer Coated Fe 2 O 3 Cocatalyst for the Promoted Activity of Plasma‐Sputtered BiVO 4 Photoanode

To simultaneously improve the hole extraction ability of the BiVO 4 photoanode and accelerate the surface reaction kinetics, herein, a carbon nanolayer conformally coated Fe 2 O 3 (C−Fe 2 O 3 ) as oxygen evolution catalyst (OEC) is loaded on the H 2 plasma treated nanoporous BiVO 4 (BVO(H 2 )) surface by a hydrothermal reaction. It is found that the H 2 plasma induced vacancies in BVO remarkably increases the conductivity, and the C−Fe 2 O 3 enables hole extraction from the bulk to the surface as well as efficient hole injection to the electrolyte. As a result, the C−Fe 2 O 3 /BVO(H 2 ) photoanode achieves a photocurrent density of 4.4 mA/cm 2 at 1.23 V vs. reversible hydrogen electrode (RHE) and an ABPE value of 1.5 % at 0.68 V vs. RHE, which are 4.8‐fold and 13‐fold higher than that of BVO photoanode, respectively.