Efficient hydrogen generation from aqueous protons through direct conversion of solar energy is an essential prerequisite of a future hydrogen economy and easily accessible renewable energy. For achieving this goal, the effective synthesis of a catalyst that can promote the hydrogen evolution reaction (HER) is in demand. Several mononuclear non-noble metal complexes carrying non-innocent S donating ligands have been reported as efficient photocatalysts and electrocatalysts for proton reduction. A thorough understanding of the elementary steps of hydrogen formation allows one to derive structure–property relationships that can guide future catalyst design. In this review, we highlight the mechanisms of the homogeneous HER for these catalysts in the light of photocatalytic, electrocatalytic and computational data with the main concern of elucidating the interplay between the localization of the electron density and the hydrogen evolution reaction pathway. In addition, the effects of π-conjugation, heteroatoms and electron accepting/donating moieties on the basicity of the metal center and catalyst overpotential are discussed to rationalize the formation of a metal or ligand hydrid intermediate. Moreover, some suggestions are provided for future use in the design of effective HER catalysts.

中文翻译：

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非纯硫配位金属配合物产氢反应机理的最新进展

通过直接转换太阳能从含水质子产生有效的氢是未来氢经济和易于获得的可再生能源的基本前提。为了实现该目标，需要能够促进氢析出反应（HER）的催化剂的有效合成。已经报道了几种带有非纯S供体的单核非贵金属配合物，作为用于质子还原的有效光催化剂和电催化剂。对氢形成基本步骤的透彻理解使人们可以推导结构与性质之间的关系，从而指导未来的催化剂设计。在本综述中，我们将根据光催化作用着重说明这些催化剂的均相HER机理，电催化和计算数据，其主要关注点在于阐明电子密度的局限性与析氢反应路径之间的相互作用。此外，讨论了π-共轭，杂原子和电子接受/给体部分对金属中心碱度和催化剂超电势的影响，以合理化金属或配体氢化物中间体的形成。而且，提供了一些建议，供将来在有效的HER催化剂的设计中使用。讨论了金属中心的碱度和催化剂超电势上的杂原子和电子接受/给体部分，以合理化金属或配体氢化物中间体的形成。而且，提供了一些建议，供将来在有效的HER催化剂的设计中使用。讨论了金属中心的碱度和催化剂超电势上的杂原子和电子接受/给体部分，以合理化金属或配体氢化物中间体的形成。而且，提供了一些建议，供将来在有效的HER催化剂的设计中使用。