Water electrolysis is potentially a clean and sustainable process for electrochemical hydrogen production. This review thoroughly examines strategies to improve the performance of electrode and electrocatalyst layers and their influence on lowering the overpotential required for hydrogen-related reactions, thereby reducing the resistance characteristics, improving the electrochemically active surface area, and raising the electrolyzer efficiency. In particular, it emphasizes the important functions of morphological modification, atomic doping, and defect/vacancy engineering. The review begins with describing the operating mechanisms of several electrolysis technologies—including alkaline water electrolysis (AWE), proton exchange membrane water electrolyzer (PEMWE), anion exchange membrane water electrolyzer (AEMWE), and solid oxide electrolysis (SOE). Further, a major part of discussion is dedicated to how morphological control of the electrode and electrocatalyst, doping, and vacancy engineering are used to maximize performance across various technologies. Additionally, the binder-free electrocatalysts coating techniques (vapor deposition methods, direct growth, electrodeposition, and anodizing) have been presented as improvement strategies for electrolyzers. By focusing on commonly used components and techniques, this article thoroughly explores important link with performance across above-mentioned electrolyzers.

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