Electrochemical water splitting is regarded as a most effective hydrogen production technique. In fact, quite a few exceptional electrocatalysts, processes, and even large‐scale demonstrations have been developed. In particular, some amorphous catalysts have become well‐known for their extraordinary performance on account of their disordered structure, numerous, uniformly distributed active sites with high unit activity and better stability that outshine their single‐crystalline counterparts. Herein, a review of recent research advances of amorphous catalysts used in electrocatalytic water splitting are provided, including both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Particularly, the scaled‐up application of amorphous catalysts with multifarious compositions and diverse heterostructures in electrolyzing water and the reason why amorphous catalysts exhibit excellent catalytic performance are emphasized on. In addition, the mechanism of water electrolysis and the evaluation criteria of catalytic properties are analyzed in detail. Finally, the broader development outlook of amorphous catalysts is discussed.

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High‐entropy materials (HEMs) have been in the spotlight as emerging catalysts for electrochemical water splitting. In particular, HEM catalysts feature multi‐element active sites and unsaturated coordination as well as entropy stabilization in comparison with their single‐element counterparts. Herein, a comprehensive overview of HEM catalysts used in electrochemical water splitting is provided, covering both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Particularly, the review begins with discussions of the concept and structure of HEMs. In addition, effective strategies for rationally designing HEMs on the basis of computational techniques and experimental aspects is described. Importantly, the importance of computationally aided methods, that is, density functional theory calculations, high‐throughput screening, and machine learning, to the discovery and design of HEMs, is described. Furthermore, the applications of HEMs in the field of water electrolysis are reviewed. Eventually, an outlook regarding the prospects and future opportunities for HEMs is provided.

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Metal‐halide perovskites possess great potential for electrochemical water splitting that has not been realized due to their intolerance to water. Here, methylammonium lead halide perovskites (MAPbX3) are used to electrocatalyze water oxidation in aqueous electrolytes by creating MAPbX3@AlPO‐5 host–guest composites. Due to the protective feature of the zeolite matrix, halide perovskite nanocrystals (NCs) confined in aluminophosphate AlPO‐5 zeolites achieve an excellent stability in water. The resultant electrocatalyst undergoes dynamic surface restructuring during the oxygen evolution reaction (OER) with the formation of an edge‐sharing α‐PbO2 active layer. The existence of charge‐transfer interactions at the MAPbX3/α‐PbO2 interface significantly modulates the surface electron density of the α‐PbO2 and optimizes the adsorption free energy of oxygen‐containing intermediate species. Furthermore, the soft‐lattice nature of halide perovskites enables more facile triggering of lattice‐oxygen oxidation of nanostructured α‐PbO2, exhibiting pH‐dependent OER activity and non‐concerted proton‐electron transfer for MAPbX3@AlPO‐5 composite. As a result, the developed MAPbBr3@AlPO‐5 composite manifests an ultralow overpotential of 233 mV at 10 mA cm−2 in 1 m KOH. These findings offer facile access to halide perovskite applied to water electrolysis with enhanced intrinsic activity, providing a new paradigm for designing high‐efficiency OER electrocatalysts.