Dalle Carbonare Nicola, Boaretto Rita, Caramori Stefano, Argazzi Roberto, Dal Colle Maurizio, Pasquini Luca, Bertoncello Renzo, Marelli Marcello, Evangelisti Claudio, Bignozzi Carlo Alberto
Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 11-17, 44121 Ferrara, Italy.
CNR/ISOF c/o Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 11-17, 44121 Ferrara, Italy.
Molecules. 2016 Jul 20;21(7):942. doi: 10.3390/molecules21070942.
Doping hematite with different elements is a common strategy to improve the electrocatalytic activity towards the water oxidation reaction, although the exact effect of these external agents is not yet clearly understood. Using a feasible electrophoretic procedure, we prepared modified hematite films by introducing in the deposition solution Ti(IV) butoxide. Photoelectrochemical performances of all the modified electrodes were superior to the unmodified one, with a 4-fold increase in the photocurrent at 0.65 V vs. SCE in 0.1 M NaOH (pH 13.3) for the 5% Ti-modified electrode, which was the best performing electrode. Subsequent functionalization with an iron-based catalyst led, at the same potential, to a photocurrent of ca. 1.5 mA·cm(-2), one of the highest achieved with materials based on solution processing in the absence of precious elements. AFM, XPS, TEM and XANES analyses revealed the formation of different Ti(IV) oxide phases on the hematite surface, that can reduce surface state recombination and enhance hole injection through local surface field effects, as confirmed by electrochemical impedance analysis.
用不同元素掺杂赤铁矿是提高水氧化反应电催化活性的常见策略，尽管这些外加试剂的确切作用尚未完全明确。我们采用一种可行的电泳方法，通过在沉积溶液中引入丁醇钛（IV）制备了改性赤铁矿薄膜。所有改性电极的光电化学性能均优于未改性电极，在0.1 M NaOH（pH 13.3）中，相对于饱和甘汞电极（SCE），5%钛改性电极在0.65 V时的光电流增加了4倍，该电极是性能最佳的电极。随后用铁基催化剂进行功能化处理，在相同电位下，光电流约为1.5 mA·cm⁻²，这是在无贵金属元素的情况下基于溶液处理的材料所达到的最高值之一。原子力显微镜（AFM）、X射线光电子能谱（XPS）、透射电子显微镜（TEM）和X射线吸收近边结构（XANES）分析表明，赤铁矿表面形成了不同的二氧化钛（IV）相，这可以减少表面态复合，并通过局部表面场效应增强空穴注入，电化学阻抗分析证实了这一点。
