Solution Process–Based Facile Flame–Boosted Low‐Valence Transition Metal Doping on Pristine Oxide for Highly Enhanced Photoelectrochemical Solar Water Oxidation Reaction

ABSTRACT As for the high sustainable solar hydrogen production via water splitting, transition metal doping on an oxide photoanode in photoelectrochemical (PEC) cells has been recognized as an effective approach. However, conventional thermal‐diffusion‐mediated doping strategies face the challenge of resolving sluggish catalytic kinetics for oxygen evolution reaction (OER) and its practical utilization for the synthesis of photoanode films. Herein, we introduce facile ultrafast flame‐boosted doping of Mo into a BiVO 4 (FL MoBVO) film for 20 s to achieve an efficient PEC OER. Mo elements in a low‐valence state (i.e., Mo 6− δ ) and Mo 6+ are successfully doped into the photoanode, which manipulate the energy band structure, facilitating the downward shift of band edges and promoting the surface catalytic kinetics. Consequently, the flame‐boosted Mo‐doping results in superior PEC performance in a mild environment with neutral electrolyte without introducing any other additives or co‐catalysts, where the photocurrent density at 1.23 V RHE under 1 sun illumination in pH 7 is outstandingly enhanced, over 9‐fold higher than that of a pristine BiVO 4 . The flame‐boosted doping induces significantly enhanced photoexcited charge transport and catalytic reaction kinetics performances simultaneously. Our report provides the effective strategy boosting both the thermodynamic and kinetic charge migration properties for sustainable materials.