Reith Lukas, Lienau Karla, Triana C A, Siol Sebastian, Patzke Greta R
Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
ACS Omega. 2019 Sep 13;4(13):15444-15456. doi: 10.1021/acsomega.9b01677. eCollection 2019 Sep 24.
The development of efficient, stable, and economic water oxidation catalysts (WOCs) is a forefront topic of sustainable energy research. We newly present a comprehensive three-step approach to systematically investigate challenging relationships among preparative history, properties, and performance in heterogeneous WOCs. To this end, we studied (1) the influence of the preparative method on the material properties and (2) their correlation with the performance as (3) a function of the catalytic test method. Spinel-type CoO was selected as a clear-cut model WOC and synthesized via nine different preparative routes. In search of the key material properties for high catalytic performance, these cobalt oxide samples were characterized with a wide range of analytical methods, including X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, Raman spectroscopy, BET surface area analysis, and transmission electron microscopy. Next, the corresponding catalytic water oxidation activities were assessed with the three most widely applied protocols to date, namely, photocatalytic, electrocatalytic, and chemical oxidation. The activity of the CoO samples was found to clearly depend on the applied test method. Increasing surface area and disorder as well as a decrease in oxidation states arising from low synthesis temperatures were identified as key parameters for high chemical oxidation activity. Surprisingly, no obvious property-performance correlations were found for photocatalytic water oxidation. In sharp contrast, all samples showed similar activity in electrochemical water oxidation. The substantial performance differences between the applied protocols demonstrate that control and comprehensive understanding of the preparative history are crucial for establishing reliable structure-performance relationships in WOC design.
开发高效、稳定且经济的水氧化催化剂（WOCs）是可持续能源研究的前沿课题。我们首次提出了一种全面的三步方法，以系统地研究多相WOCs中制备历史、性质和性能之间具有挑战性的关系。为此，我们研究了：（1）制备方法对材料性质的影响；（2）它们与作为（3）催化测试方法函数的性能之间的相关性。选择尖晶石型CoO作为明确的模型WOC，并通过九种不同的制备路线合成。为了寻找具有高催化性能的关键材料性质，这些氧化钴样品采用了多种分析方法进行表征，包括X射线吸收光谱、X射线光电子能谱、粉末X射线衍射、拉曼光谱、BET表面积分析和透射电子显微镜。接下来，使用迄今为止应用最广泛的三种方案，即光催化、电催化和化学氧化，评估相应的催化水氧化活性。发现CoO样品的活性明显取决于所应用的测试方法。增加表面积和无序度以及由于低合成温度导致的氧化态降低被确定为高化学氧化活性的关键参数。令人惊讶的是，在光催化水氧化中未发现明显的性质-性能相关性。与之形成鲜明对比的是，所有样品在电化学水氧化中表现出相似的活性。所应用方案之间的显著性能差异表明，控制和全面理解制备历史对于在WOC设计中建立可靠的结构-性能关系至关重要。
