Precise Lattice-Strain Modulation of Hematite Enabled by Gradient Doping of Mn for Enhanced Photoelectrocatalytic Oxidative C─C Bond Scission

Abstract

The high-value utilization of biomass feedstock is fascinating but limited by efficient C─H activation to break C─C bonds. Herein, F-Fe2O3-Mn photoanodes with modulable compressive strain are fabricated by gradient infusion of Mn into F-doped hematite (F-Fe2O3), which is illustrated to be highly efficient for oxidative C─C bond cleavage of various bio-based 1,2-diols to produce benzoic acids or aromatic ketones (94.5–97.2% yields) in photoelectrocatalytic (PEC) device, coupling with a high H2 production of 1180 μmol cm−2 (≈96% yield). The gradient doping of Mn species into the photoelectrode bulk results in improved photoexcited carriers separation and transfer efficiency of the photoelectrode (3.41 mA cm−2). On the other hand, the lattice distortion induced by Mn doping also leads to a strain effect on F─Fe2O3─Mn, which can precisely modulate the photoelectrode electronic structure. Control experiments, in situ characterization, and theoretical calculations elaborate that compressive strain is capable of adjusting the position of the d-band center to facilitate C─H activation, remarkably enabling PEC oxidative C─C bond breaking of 1,2-diol and the desorption of the oxidized product. This “one-stone-two-bird” strategy presents a straightforward protocol for efficiently breaking C─C bonds in organic and biomass transformations via PEC oxidation.