PhotoElectroChemical applicCation of Uranium oxides for enhanced LIght AbsoRption (PECULIAR)

带隙能在2.0-2.6 eV范围内的铀氧化物具有良好的电学和催化性能，主要是由铀阳离子的价动力学驱动的，是一种很有前途的光电化学水分解反应电极材料。尽管被认为是一种稀有元素，但由于挥发性、腐蚀性和有毒化合物的意外泄漏，最初作为核燃料浓缩过程中的废流产生的大量贫铀源(例如，仅在美国就有70万吨UF6)目前被储存起来，没有任何进一步应用的前景，从而构成永久的环境危害。鉴于其有趣的电子和结构性质(贫化)，铀氧化物是潜在有用的能源应用材料，然而，由于可获得性有限，到目前为止还没有探索替代概念。首次获得了用于气相沉积(热镀和等离子体辅助化学气相沉积)氧化铀膜的铀金属-有机前驱体，并研究了所得薄膜在水分解装置中作为潜在光电极的可能性。申请者的初步研究说明了UOx在(照片)化学能量转换周期中的巨大潜力和大部分未开发的潜力。铀氧化物是适合于PEC应用的半导体材料，因为它们的带隙能量意味着在太阳光谱的可见光部分有很高的光子吸收，更重要的是，它们的带边位置跨越了氢势和氧势。这项提议将探索不同的铀氧化物相和晶型在光电化学实验中的适用性。与著名的半导体金属氧化物如二氧化钛、三氧化二铁和氧化锌相比，铀氧化物的化学和材料方面的研究较少，因此这项工作将伴随着从头算密度泛函计算，以了解关于水分解反应的基本过程。此外，还将通过理论研究和实验验证来研究U：O比对UOx与其他电势光阳极材料的带隙能和热力学稳定性的影响。此外，还将详细阐述杂质(掺杂剂)以及与异质结构中已有的有效吸收相结合的影响，以详细了解光电催化性能，并评估从水中有效利用铀氧化物生产氢气的可能性。

Uranium oxides with band-gap energies in the range of 2.0 - 2.6 eV coupled with their good electrical and catalytic properties mostly driven by facile valence dynamics of the uranium cations are promising electrode materials in photoelectrochemical water splitting reactions. Although being considered a scarce element, huge amounts of depleted uranium sources (e.g.,alone 700,000 Tons UF6 in the USA) originally produced as waste streams in the enrichment process of nuclear fuels, is currently stored without any prospect for further applications that poses a perpetual environmental hazard, due to accidental release of volatile, corrosive and toxic compounds. In view of their interesting electronic and structural properties (depleted) uranium oxides are potentially useful materials for energy applications, however alternative concepts have been not probed so far due to the limited accessibility. For the first time uranium metal-organic precursors for the gas phase deposition (thermal and plasma-assisted chemical vapor deposition) of uranium oxide coatings have been achieved and the resulting thin-films have been investigated as potential photoelectrodes in water-splitting setups. Preliminary studies by the applicants illustrate the enormous and mostly unexplored potential of UOx in (photo)chemical energy conversion cycles. Uranium oxides are suitable semiconductor materials for PEC applications due to their band gap energies that imply high photon absorption in the visible part of the solar spectrum, and more importantly the fact that their band edge positions straddle with the hydrogen and oxygen potentials. The proposed - PECULIAR - will explore the suitability of different uranium oxide phases and polymorphs in photoelectrochemical experiments. Compared to well-known semiconductor metal oxides such as TiO2, Fe2O3 and ZnO, the chemistry and materials aspects of uranium oxides is scantily explored and therefore this effort will be accompanied by ab-initio DFT calculationsto understand the underlying processes with respect to water-splitting reactions . In addition, influence of U:O ratio on the band gap energies as well thermodynamical stability of UOx with other potential photoanode materials will be investigated by theoretical studies followed by their experimental validation. Further, the effect of impurities (dopants) and combination with already existing potent absorbers in heterostructures will be elaborated for a detailed understanding of the photoelectrocatalytical performance and the assessment of the beneficial use of uranium oxide to produce hydrogen from water.