Bauerfeind Katharina C L, Bredow Thomas
Mulliken Center for Theoretical Chemistry, Institute of Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4-6, 53115, Bonn, Germany.
Photochem Photobiol Sci. 2022 Jun;21(6):1091-1100. doi: 10.1007/s43630-022-00201-7. Epub 2022 Mar 31.
Zinc ferrite ZnFe[Formula: see text]O[Formula: see text] belongs to the spinel-type ferrites that have been proposed as photocatalysts for water splitting. The electronic band gap and the band edge positions are of utmost importance for the efficiency of the photocatalytic processes. We, therefore, calculated the absolute band energies of the most stable surface of ZnFe[Formula: see text]O[Formula: see text], the Zn-terminated (100) surface at self-consistent hybrid density functional theory level. The effect of Fe- and Zn-rich environments, cation exchange as antisite defects and implicit solvation on the band positions is investigated. Calculated flat band potentials of the pristine surface model ranges from [Formula: see text] to [Formula: see text] V against SHE in vacuum. For Zn-rich (Fe-rich) models this changes 0.3-0.9 (0.0-0.7) V against SHE. Fe-rich models are closest to the experimental range of reported flat band potentials. Solvent effects lower the calculated flat band potentials by up to 1.8 eV. The calculated band gaps range from 1.5 to 2.9 eV in agreement with previous theoretical work and experiment. Overall, our calculations confirm the experimentally observed low activity of ZnFe[Formula: see text]O[Formula: see text] and its dependence on preparation conditions.
铁酸锌ZnFe₂O₄属于尖晶石型铁氧体，已被提议用作光催化水分解的催化剂。电子带隙和带边位置对于光催化过程的效率至关重要。因此，我们在自洽混合密度泛函理论水平上计算了ZnFe₂O₄最稳定表面（锌端接的(100)表面）的绝对带能。研究了富铁和富锌环境、作为反位缺陷的阳离子交换以及隐式溶剂化对带位置的影响。在真空中，原始表面模型计算的平带电位相对于标准氢电极（SHE）范围为1.0至1.7 V。对于富锌（富铁）模型，相对于SHE，此值变化了0.3 - 0.9（0.0 - 0.7）V。富铁模型最接近报道的平带电位的实验范围。溶剂效应使计算的平带电位降低高达1.8 eV。计算的带隙范围为1.5至2.9 eV，与先前的理论工作和实验一致。总体而言，我们的计算证实了实验观察到的ZnFe₂O₄的低活性及其对制备条件的依赖性。
