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Electrocatalytic water splitting is one of the most promising sustainable energy conversion technologies, but is limited by the sluggish electrochemical reactions. Inorganic nanomaterials have been widely used as efficient catalysts for promoting the electrochemical kinetics. Several approaches to optimize the activities of these nanocatalysts have been developed. The electronic structures of the catalysts play a pivotal role in governing the activity and thus have been identified as an essential descriptor. However, the underlying working mechanisms related to the refined electronic structures remain elusive. To establish the structure–electronic‐behavior–activity relationship, a comprehensive overview of the developed strategies to regulate the electronic structures is presented, emphasizing the surface modification, strain, phase transition, and heterostructure. Current challenges to the fundamental understanding of electron behaviors in the nanocatalysts are fully discussed. Making split happen: Strategies to regulate electronic structures of materials to optimize their electrocatalytic activities in water splitting are summarized in this Review. The structure–electronic‐behavior–activity relationships are highlighted as well as current challenges on understanding the electronic behaviors. [ABSTRACT FROM AUTHOR]

Efficient hydrogen production by water electrolysis is significant for the development of renewable energy. To date, the cost and scarcity of noble‐metal catalysts are limiting their scale‐up applications. To overcome the current challenge, high‐performance novel electrocatalysts are required to speed up the commercialization of electrolysis technology. Notably, the sluggish electrode reactions, namely, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), especially the latter, have been the main rate‐limiting factor for water splitting. Phosphate, as a new series of OER electrocatalysts, has attracted enormous attentions, owing to its unique lattice structure geometry. The phosphate group not only benefits the adsorption of water molecule but also facilitates the oxyhydrate of metal site and dissociation of water. This Minireview provides a brief summary of the recent progresses of phosphate‐based electrocatalysts, discusses the relationship between crystal structure and catalytic activity, and presents the challenges of phosphate electrocatalysts. ′Cats out of the bag: This Minireview details the relationship between crystal structure and catalytic activity of phosphate‐based electrocatalysts and provides the methods used to fabricate phosphate‐based electrocatalysts. [ABSTRACT FROM AUTHOR]

Developing highly efficient electrocatalysts for hydrogen generation from water has been a crucial option for future energy conversion and storage. Rhenium dichalcogenides (ReX2, X=S or Se) have attracted tremendous research interests due to their unique distorted‐1T phase and anisotropic electronic structure. So far, there is no report about S doped ReSe2 electrocatalyst. In this work, we present a three‐dimensional nanosheets electrocatalyst derived from sulfur‐doped rhenium selenide (ReSe2(1–x)S2x) grown on carbon fiber paper (CFP) for water splitting. It is noting that the catalytic activity could be significantly fine‐tuned by controlling quantity of sulfur dopant. ReSe1.78S0.22/CFP cathode exhibits the best performance with a Tafel slope of 84 mV dec−1, an overpotential of 123 mV to drive the current density of 10 mA cm−2 as well as a long‐term stability of 30 h. The X‐ray photoelectron spectroscopy and density functional theory calculations confirm that sulfur‐doped structure, especially the dangling sulfur atoms adsorbed on the surface Se atom kars, achieves a more thermoneutral hydrogen adsorption energy, conducing an optimized catalytic activity of the basal plane. This study demonstrates that S doped ReSe2 could be a promising candidate electrocatalyst for hydrogen evolution. Positive for doping: A sulfur‐doped rhenium selenide nanosheets electrocatalyst is developed for efficient hydrogen evolution, supported by experimental analyses and theoretical simulation. [ABSTRACT FROM AUTHOR]

High-performance and affordable electrocatalysts from earth-abundant elements are desirably pursued for water splitting involving hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Here, a bifunctional electrocatalyst of highly crystalline Mo2C nanoparticles supported on carbon sheets (Mo2C/CS) was designed toward overall water splitting. Owing to the highly active catalytic nature of Mo2C nanoparticles, the high surface area of carbon sheets and efficient charge transfer in the strongly coupled composite, the designed catalysts show excellent bifunctional behavior with an onset potential of −60 mV for HER and an overpotential of 320 mV to achieve a current density of 10 mA cm−2 for OER in 1 m KOH while maintaining robust stability. Moreover, the electrolysis cell using the catalyst only requires a low cell voltage of 1.73 V to achieve a current density of 10 mA cm−2 and maintains the activity for more than 100 h when employing the Mo2C/CS catalyst as both anode and cathode electrodes. Such high performance makes Mo2C/CS a promising electrocatalyst for practical hydrogen production from water splitting. [ABSTRACT FROM AUTHOR]

The Cover picture shows a new bifunctional electrocatalyst of strongly coupled molybdenum carbide on carbon sheets (Mo2C@CS) toward overall water splitting. Benefitting from the synergistic advantages of active sites on basal planes, high surface area, and unique lamellar structure of supporting carbon sheets, the resulting Mo2C@CS exhibits superior electrocatalytic activity for both hydrogen and oxygen evolution reactions as well as excellent stability. Remarkably, the composite is able to serve as both anode and cathode catalyst for the two‐electrode water electrolyzer on page 3540 in Issue 18, 2017 (DOI: 10.1002/cssc.201701276). [ABSTRACT FROM AUTHOR]