Peter A. Rock Thermochemistry Laboratory and Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit, University of California, Davis, CA 95616, USA.
Proc Natl Acad Sci U S A. 2013 May 28;110(22):8801-6. doi: 10.1073/pnas.1306623110. Epub 2013 May 10.
Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn(3+)/Mn(4+) ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states.
先前的测量表明，钙锰氧化物纳米颗粒比二元锰氧化物（Mn3O4、Mn2O3 和 MnO2）更适合水氧化催化剂。这种增强的可能原因涉及多种因素的结合：钙锰氧化物材料具有层状结构，热力学稳定性高，表面积大，低表面能表明 H2O 在内外表面的结合相对较松，并且它们具有混合价态的锰，其内部氧化焓与 Mn(3+)/Mn(4+) 比值无关，且比 Mn2O3-MnO2 对小得多。这些因素通过为溶质和水提供易于接近活性位点的途径以及不同氧化态锰之间的电子转移来提高催化能力。
