splitting (2H 2 O → 2H 2 + O 2 ), consisting of hydrogen evolution and oxygen evolution reaction (HER/OER), can convert electricity to chemical energy in H 2 and O 2 for further energy applications. The practical application of overall water splitting, however, is still limited due to the lack of effective and stable catalysts to reduce reaction energy barrier and enhance Faraday efficient for both reactions. [6][7][8][9][10] Different materials have been studied for overall water splitting catalysis, like metal chalcogenides, metal carbides, oxides, etc. The transition metal carbides, especially graphene, have a better electroconductivity, ductility, and high surface area which display excellent performance in water splitting. [11][12][13] Oxides as another abundant species on the earth also show better water splitting performance, but their stability in hard media is not very good. [14][15][16] The layered double hydroxides (LDH) with unique structure, abundant interstratified electrons and channels for intermediate adsorption and desorption display wonderful water splitting performance. [17][18][19][20] Additionally, the metalorganic frameworks (MOFs) and their based nanocrystals as newly nanomaterials have got much attention in various fields, but their structure limited the active sites exposure for the complete coordinative metal sites. [21][22][23][24][25] Therefore, it is important to enable the cost-effective, large-scale production of these catalysts, and further improve the performance and efficiency of overall water splitting.Transition metal chalcogenides have many different compositions with various lattice structure, while those materials also have unique electronic structures. [26] Based on those superior properties, the transition metal chalcogenides show promising application in many energy applications, [27] such as electrochemical catalysis, photocatalysis, metal-air batteries, and other energy conversion reactions. Especially for their abundant defects sties, [26][27][28] tunable electronic structure, [29][30][31][32] and various morphology, [33][34][35][36][37] the transition metal chalcogenides exhibit boosting performance for water splitting. However, they still have some disadvantages, such as poor conductivity, activity, and stability, in water splitting limited their large-scale industrial application. [38][39][40][41][42] How to synthesize the active and stable transition metal chalcogenides is still a big challenge for wide application. In this Review, the several promising strategies are designed to prepare the active and stable transition metal chalcogenides (Scheme 1). → 2H 2 + O 2 ) is a very promising avenue to effectively and environmentally friendly produce highly pure hydrogen (H 2 ) and oxygen (O 2 ) at a large scale. Different materials have been developed to enhance the efficiency for water splitting. Among them, chalcogenides with unique atomic arrangement and high electronic transport show interesting catalytic properties in various electrochemical reactions, such as the ...

The oxygen‐related electrochemical process, including the oxygen evolution reaction and oxygen reduction reaction, is usually a kinetically sluggish reaction and thus dominates the whole efficiency of energy storage and conversion devices. Owing to the dominant role of the oxygen‐related electrochemical process in the development of electrochemical energy, an abundance of oxygen‐related electrocatalysts is discovered. Among them, perovskite‐type materials with flexible crystal and electronic structures have been researched for a long time. However, most perovskite materials still show low intrinsic activity, which highlights the importance of activation strategies for perovskite‐type structures to improve their intrinsic activity. In this review, the recent progress of the activation strategies for perovskite‐type structures is summarized and their related applications in oxygen‐related electrocatalysis reactions, including electrochemistry water splitting, metal–air batteries, and solid oxide fuel cells are discussed. Furthermore, the existing challenges and the future perspectives for the designing of ideal perovskite‐type structure catalysts are proposed and discussed.

Oriented synthesis of transition metal sulfides (TMSs) with controlled compositions and crystal structures has long been promising for electronic devices and energy applications. Liquid-phase cation exchange (LCE) is a wellstudied route by varying the compositions. However, achieving crystal structure selectivity is still a great challenge. Here, we demonstrate gas-phase cation exchange (GCE), which can induce a specific topological transformation (TT), for the synthesis of versatile TMSs with identified cubic or hexagonal crystal structures. The parallel six-sided subunit (PSS), a new descriptor, is defined to describe the substitution of cations and the transition of the anion sublattice. Under this principle, the band gap of targeted TMSs can be tailored. Using the photocatalytic hydrogen evolution as an example, the optimal hydrogen evolution rate of a zinc-cadmium sulfide (ZCS4) is determined to be 11.59 mmol h À 1 g À 1 , showing a 36.2-fold improvement over CdS.

Interfacial nanostructured materials have stimulated extensive interests in the research areas of green energy production and conversion due to their unique structures and performance. These interfacial crystalline structures with rich intrinsic defects, such as oxygen vacancies, adatoms, grain boundaries, and substitutional impurities, have led to unique activities in a variety of catalytic reactions. The rational design and engineering development of the interfaces provide an attractive way to optimize the catalytic performance and finally improve the efficiency of energy conversion and storage. Herein, a comprehensive overview of interfacial inorganic nanostructures and their electrocatalytic applications are summarized, and some future challenge and opportunity have also been proposed.

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