Ertl Michael, Ma Zili, Thersleff Thomas, Lyu Pengbo, Huettner Sven, Nachtigall Petr, Breu Josef, Slabon Adam
Institute of Inorganic Chemistry , RWTH Aachen University , Landoltweg 1 , Aachen D-52056 , Germany.
Department of Materials and Environmental Chemistry , Stockholm University , Svante Arrhenius väg 16 C , Stockholm 10691 , Sweden.
Inorg Chem. 2019 Aug 5;58(15):9655-9662. doi: 10.1021/acs.inorgchem.9b00327. Epub 2019 Jul 16.
Mössbauerite, a trivalent iron-only layered oxyhydroxide, has been recently identified as an electrocatalyst for water oxidation. We investigated the material as potential cocatalyst for photoelectrochemical water oxidation on semiconductor photoanodes. The band edge positions of mössbauerite were determined for the first time with a combination of Mott-Schottky analysis and UV-vis diffuse reflectance spectroscopy. The positive value of the Mott-Schottky slope and the flatband potential of 0.34 V vs reversible hydrogen electrode (RHE) identifies the material as an n-type semiconductor, but bare mössbauerite does not produce noticeable photocurrent during water oxidation. Type-II heterojunction formation by facile drop-casting with WO thin films yielded photoanodes with amended charge carrier separation and photocurrents up to 1.22 mA cm at 1.23 V vs RHE. Mössbauerite is capable of increasing the charge carrier separation at lower potential and improving the photocurrent during photoelectrochemical water oxidation. The rise in photocurrent of the mössbauerite-functionalized WO photoanode thus originates from improved charge carrier separation and augmented hole collection efficiency. Our results highlight the potential of mössbauerite as a second-phase catalyst for semiconductor electrodes.
纤铁矿，一种仅含三价铁的层状羟基氧化物，最近被确定为水氧化的电催化剂。我们研究了该材料作为半导体光阳极上光电化学水氧化潜在助催化剂的性能。通过莫特-肖特基分析和紫外-可见漫反射光谱相结合的方法首次测定了纤铁矿的能带边缘位置。莫特-肖特基斜率的正值和平带电位为相对于可逆氢电极（RHE）的0.34 V，表明该材料为n型半导体，但裸纤铁矿在水氧化过程中不会产生明显的光电流。通过与WO薄膜简单滴铸形成II型异质结，得到了电荷载流子分离得到改善、在相对于RHE为1.23 V时光电流高达1.22 mA cm的光阳极。纤铁矿能够在较低电位下提高电荷载流子的分离，并在光电化学水氧化过程中提高光电流。因此，纤铁矿功能化的WO光阳极光电流的增加源于电荷载流子分离的改善和空穴收集效率的提高。我们的结果突出了纤铁矿作为半导体电极第二相催化剂的潜力。
