Synergistic Effect of Metal–Organic Framework-Derived TiO<sub>2</sub> Nanoparticles and an Ultrathin Carbon Layer on Passivation of Hematite Surface States
Juan Wu, Mixiang Qi, Gang Wang, Bin Yu, Chengdong Liu, Wei Hou, Weisheng Liu
Abstract
A passivation layer plays an important role in suppressing charge recombination on surface trap states. However, the effect of a single passivation layer is limited. Building a passivation system containing multiple passivation layers with different functions for efficient charge separation presents a challenge. In this study, we demonstrate the synergistic passivation effect between a metal–organic framework-derived TiO2 nanoparticle layer and an ultrathin carbon layer, which facilitates the charge separation of an α-Fe2O3 photoanode with a surface separation efficiency of 57%. The α-Fe2O3/TiO2/C photoanode generates a photocurrent of 1.93 mA cm–2 at 1.23 V vs a reversible hydrogen electrode, which is about 3.22 times higher than that of pristine α-Fe2O3. After the introduction of the cocatalyst β-FeOOH onto the α-Fe2O3/TiO2/C photoanode, a higher photocurrent of 2.95 mA cm–2 is generated under the same condition without doping and constructing a heterojunction.