Serra J M, Balaguer M, Santos-Blasco J, Borras-Morell J F, Garcia-Baños B, Plaza-Gonzalez P, Catalán-Martínez D, Penaranda-Foix F, Domínguez A, Navarrete L, Catala-Civera J M
Instituto de Tecnología Química, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Avenida de los Naranjos s/n, Valencia, 46022, Spain.
Instituto ITACA, Universitat Politècnica de València, Camino de Vera, Valencia, 46022, Spain.
Mater Horiz. 2023 Nov 27;10(12):5796-5804. doi: 10.1039/d3mh01339a.
The industrial adoption of low-carbon technologies and renewable electricity requires novel tools for electrifying unitary steps and efficient energy storage, such as the catalytic synthesis of valuable chemical carriers. The recently-discovered use of microwaves as an effective reducing agent of solid materials provides a novel framework to improve this chemical-conversion route, thanks to promoting oxygen-vacancy formation and O-surface exchange at low temperatures. However, many efforts are still required to boost the redox properties and process efficiency. Here, we scrutinise the dynamics and the physicochemical dependencies governing microwave-induced redox transformations on solid-state ion-conducting materials. The reduction is triggered upon a material-dependent induction temperature, leading to a characteristically abrupt rise in electric conductivity. This work reveals that the released O yield strongly depends on the material's composition and can be tuned by controlling the gas-environment composition and the intensity of the microwave power. The reduction effect prevails at the grain surface level and, thus, amplifies for fine-grained materials, and this is ascribed to limitations in oxygen-vacancy diffusion across the grain compared to a microwave-enhanced surface evacuation. The precise cyclability and stability of the redox process will enable multiple applications like gas depuration, energy storage, or hydrogen generation in several industrial applications.
低碳技术和可再生电力的工业应用需要新的工具来实现单一步骤的电气化和高效的能量存储，例如催化合成有价值的化学载体。最近发现微波可作为固体材料的有效还原剂，这为改进这种化学转化途径提供了一个新的框架，这得益于它在低温下促进氧空位的形成和表面氧交换。然而，仍需要付出很多努力来提高氧化还原性能和工艺效率。在这里，我们详细研究了固态离子导电材料上微波诱导的氧化还原转变的动力学和物理化学依赖性。还原反应在取决于材料的诱导温度下触发，导致电导率出现典型的突然上升。这项工作表明，释放的氧产量强烈取决于材料的组成，并且可以通过控制气体环境组成和微波功率强度来调节。还原效应在晶粒表面水平上占主导，因此对于细晶粒材料会放大，这归因于与微波增强的表面排空相比，氧空位在晶粒间扩散的限制。氧化还原过程精确的循环性和稳定性将使其能够在多种工业应用中实现气体净化、能量存储或制氢等多种应用。
