Artificial photosynthesis is considered a promising method to produce clean and renewable energy by sunlight. To accomplish this aim, development of efficient and robust catalysts for water oxidation and hydrogen production is extremely important. Owing to the advantages of easily modified structures and traceable catalytic processes, molecular water oxidation catalysts (WOCs) attract much attention during the past decade. However, the transformation of molecular WOCs to metal oxides/hydroxides or metal ions may occur under the harsh catalytic conditions, making the identification of true active species difficult. In this article, recent progress on molecular complexes acting as real catalysts or precursors toward water oxidation was briefly reviewed. We summarized the commonly used physical techniques and chemical methods that enable to distinguish homogeneous catalysts from heterogeneous catalysts. The factors that affect the nature of WOCs, such as reaction conditions, transition metal centers, and supporting ligands were discussed as well.

人工光合作用被认为是通过阳光产生清洁和可再生能源的一种有前途的方法。为了实现该目的，开发用于水氧化和制氢的有效且坚固的催化剂极为重要。由于易于修饰的结构和可追溯的催化过程的优势，分子水氧化催化剂（WOC）在过去十年中引起了广泛关注。但是，在苛刻的催化条件下可能发生分子WOC向金属氧化物/氢氧化物或金属离子的转化，从而使鉴定真正的活性物质变得困难。在本文中，简要综述了分子络合物作为水氧化的真正催化剂或前体的最新进展。我们总结了常用的物理技术和化学方法，可以区分均相催化剂和非均相催化剂。还讨论了影响WOC性质的因素，例如反应条件，过渡金属中心和支持配体。