Hydrogen evolution reaction (HER) in alkaline medium is currently a point of focus for sustainable development of hydrogen as an alternative clean fuel for various energy systems, but suffers from sluggish reaction kinetics due to additional water dissociation step. So, the state-of-the-art catalysts performing well in acidic media lose considerable catalytic performance in alkaline media. This review summarizes the recent developments to overcome the kinetics issues of alkaline HER, synthesis of materials with modified morphologies, and electronic structures to tune the active sites and their applications as efficient catalysts for HER. It first explains the fundamentals and electrochemistry of HER and then outlines the requirements for an efficient and stable catalyst in alkaline medium. The challenges with alkaline HER and limitation with the electrocatalysts along with prospective solutions are then highlighted. It further describes the synthesis methods of advanced nanostructures based on carbon, noble, and inexpensive metals and their heterogeneous structures. These heterogeneous structures provide some ideal systems for analyzing the role of structure and synergy on alkaline HER catalysis. At the end, it provides the concluding remarks and future perspectives that can be helpful for tuning the catalysts active-sites with improved electrochemical efficiencies in future.

中文翻译：

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碱性电解质中析氢的电催化剂：机制、挑战和前瞻性解决方案。

碱性介质中的析氢反应（HER）目前是氢作为各种能源系统替代清洁燃料可持续发展的焦点，但由于额外的水离解步骤，反应动力学缓慢。因此，在酸性介质中表现良好的最先进的催化剂在碱性介质中会失去相当大的催化性能。本综述总结了克服碱性 HER 动力学问题、具有改进形态的材料合成和调整活性位点的电子结构及其作为高效 HER 催化剂的应用的最新进展。它首先解释了 HER 的基本原理和电化学，然后概述了碱性介质中高效稳定的催化剂的要求。然后强调了碱性 HER 的挑战和电催化剂的局限性以及前瞻性的解决方案。它进一步描述了基于碳、贵金属和廉价金属及其异质结构的先进纳米结构的合成方法。这些异质结构为分析碱性 HER 催化中的结构作用和协同作用提供了一些理想的系统。最后，它提供了结论性意见和未来展望，这有助于调整催化剂活性位点以提高未来的电化学效率。