Synthesizing molybdenum-doped bismuth vanadate nanoneedle array as photocatalyst for water oxidation using bifunctional molybdenum as dopant and structure directing agent

Abstract

Developing one-dimensional nanostructures is one of the efficient strategies for improving short charge diffusion path and serious charge recombination of bismuth vanadate (BiVO4) as the photocatalyst for water oxidation. The well-aligned molybdenum-doped (Mo-doped) BiVO4 nanoneedle array is synthesized on transparent conducting glass via the facile one-step solution process. The Mo ion cannot only act as the dopant for enhancing the carrier density but also play the role of the structure directing agent for promoting the formation of the well-defined nanoneedle array. The highest photocurrent density of 1.62 mA/cm2 at 1.23 VRHE and the smallest onset potential of 0.34 VRHE are obtained for the 6% Mo-doped BiVO4 electrode, while the pristine BiVO4 electrode only shows the photocurrent density of 0.78 mA/cm2 and the onset potential of 0.64 VRHE at the same conditions. The better photocatalytic ability for the Mo-doped BiVO4 electrode is owing to the preferable charge-transfer path and the higher carrier density induced by the doping of Mo in BiVO4. This work firstly demonstrates that Mo-doping can attain an extra benefit of producing the well-aligned nanoneedle array. Realizing heteroatom-doping and morphology design simultaneously using the simple solution process is promising for synthesizing the efficient photocatalyst toward water oxidation. The relation between the metal dopant and the morphology evolution is expected to be developed in the future work to more understand the principle of designing photocatalysts using the heteroatom-doping technique.