Electrochemical and photoelectrochemical conversion of renewable energy sources into useful chemicals and fuels is of paramount importance for future sustainable technologies. Renewable energy conversion requires catalysts for multielectron redox reactions such as water oxidation and reduction (toward water splitting systems). Developing efficient catalysts for multielectron redox reactions is a great challenge in current science and technology. Metal oxides have been extensively researched to be applied to a large variety of photonic and electronic devices due to the wide range of electronic properties of conducting, semiconducting, and insulating and diverse catalytic properties at their surface depending on the exposing facet, as well as physical and chemical robustness under ambient conditions. We aspire to the development of an easy technique available for large-scale production of metal oxide films based on simple casting and calcination to adopt a strategy for controlling the formation and growth of metal oxide films by ligands to metal centers in precursors. We have developed an easy preparation technique of mono- and multimetallic oxide films, termed the “mixed metal-imidazole casting (MiMIC) method”, by which metal oxide films are generated tightly on various electrode substrates by casting precursor solutions or suspensions containing component metal salts in a mixed solvent of methanol/imidazole derivative as a ligand, followed by calcination. The general versatility of the MiMIC method encourages us to hunt new metal oxide films as efficient catalysts for the multielectron redox reactions, because the rigid adherability of films formed on a current collector electrode is necessary for essential evaluation of the catalytic performance of the metal oxide films. In this Account, we expound synthesis and characterization of a variety of mono- and multimetallic oxide films using the MiMIC method and its application to electro- and photoelectrocatalysis for water splitting and oxygen reduction, which are important key reactions in future sustainable technology. The adherability of these films onto the electrode surface is prominent although their morphology, crystallinity, and nanostructures depend on the metal oxide materials, which is one of the important factors to induce high performance of the metal oxide films for electro- and photoelectrocatalysis. Imidazole derivatives were found to act as a source of nitrogen for the N-doping to a metal oxide lattice, and a structure-directing agent for the anisotropic crystallization, as well as a binder among constituting nanoparticles to lead to the rigid adherability of films on the substrate. These findings surely expand material development to a great extent, by not only changing the metal compositions but also being based on band engineering due to doping of representative elements and crystal facet control of metal oxide films.

中文翻译：

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使用混合金属-咪唑铸造 （MiMIC） 方法寻找用于电和光电催化的先进金属氧化物薄膜的材料


将可再生能源电化学和光电化学转化为有用的化学品和燃料对于未来的可持续技术至关重要。可再生能源转换需要用于多电子氧化还原反应的催化剂，例如水氧化和还原（朝向水分解系统）。开发用于多电子氧化还原反应的高效催化剂是当前科学技术中的巨大挑战。金属氧化物已被广泛研究应用于各种光子和电子器件，因为其表面的导电、半导体和绝缘电子特性范围广泛，其表面具有不同的催化特性，具体取决于暴露面，以及环境条件下的物理和化学稳健性。我们渴望开发一种简单的技术，可用于基于简单铸造和煅烧的金属氧化物薄膜的大规模生产，以采用一种策略来控制配体对前驱体中金属中心的金属氧化物膜的形成和生长。我们开发了一种简单的单金属和多金属氧化物薄膜制备技术，称为“混合金属-咪唑铸造 （MiMIC） 方法”，通过浇注含有组分金属盐的前驱体溶液或悬浮液，在甲醇/咪唑衍生物作为配体的混合溶剂中，然后煅烧，在各种电极衬底上紧密生成金属氧化物薄膜。 MiMIC 方法的普遍多功能性鼓励我们寻找新的金属氧化物膜作为多电子氧化还原反应的有效催化剂，因为在集流体电极上形成的薄膜的刚性粘附性对于评估金属氧化物膜的催化性能是必要的。在本篇报道中，我们阐述了使用 MiMIC 方法合成和表征各种单金属和多金属氧化物薄膜，及其在电催化和光电催化中的作用，用于分解水和氧还原，这是未来可持续技术中的重要关键反应。尽管这些薄膜的形态、结晶度和纳米结构取决于金属氧化物材料，但这些薄膜在电极表面的粘附性很突出，这是诱导金属氧化物薄膜用于电催化和光电催化的高性能的重要因素之一。发现咪唑衍生物是 N 掺杂金属氧化物晶格的氮源，是各向异性结晶的结构导向剂，以及构成纳米颗粒之间的粘合剂，导致薄膜在基材上的刚性粘附。这些发现无疑在很大程度上扩展了材料的发展，不仅改变了金属成分，而且由于代表性元素的掺杂和金属氧化物薄膜的晶体刻面控制，它们基于能带工程。