Spontaneously Improved Adsorption of H2O and Its Intermediates on Electron-Deficient Mn(3+δ)+ for Efficient Photocatalytic H2O2 Production

Abstract

Transitional metal oxyhydroxides have been demonstrated to be the reliable cocatalysts for water oxidation reaction. However, their insufficient adsorption ability for H₂O and its intermediate products during water oxidation greatly restricts the improvement of water oxidation rate. In this study, a spontaneously improved adsorption of H₂O and its intermediates on the electron-deficient Mn^(3+δ)+ of MnOOH cocatalyst can greatly promote the rapid water oxidation to realize the efficient photocatalytic H₂O₂ production in a pure water system. In this case, amorphous MnOOH is selectively deposited on the (110) facet of AuPd-modified single-crystal BiVO₄ photocatalyst via the directionally photoinduced oxidation approach to produce AuPd/BiVO₄/MnOOH photocatalyst. Photocatalytic experiments exhibit that the as-prepared AuPd/BiVO₄/MnOOH (0.5%) photocatalyst obtains the boosted H₂O₂-evolution rate of 214 μmol∙L⁻¹ as well as exhibits an outstanding stability and reproducibility. Density functional theory calculations and X-ray photoelectron spectroscopy (XPS) characterization reveal that the free electrons of MnOOH can effectively transfer to BiVO₄ to induce the generation of electron-deficient Mn sites (Mn^(3+δ)+), which spontaneously promotes the adsorption of H₂O and its intermediates for enhancing 4-electron water oxidation reaction, resulting in an efficient H₂O₂ production. The present work about the strong interaction between cocatalyst and bulk catalyst provides a fresh idea for the rational design of highly efficient catalytic materials.

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