Sodium-ion batteries (SIBs) are considered as complementary alternatives to lithium-ion batteries for grid energy storage due to the abundance of sodium. However, low capacity, poor rate capability, and cycling stability of existing anodes significantly hinder the practical applications of SIBs. Herein, ultrathin two-dimensional SnS2 nanosheets (3-4 nm in thickness) are synthesized via a facile refluxing process toward enhanced sodium storage. The SnS2 nanosheets exhibit a high apparent diffusion coefficient of Na(+) and fast sodiation/desodiation reaction kinetics. In half-cells, the nanosheets deliver a high reversible capacity of 733 mAh g(-1) at 0.1 A g(-1), which still remains up to 435 mAh g(-1) at 2 A g(-1). The cell has a high capacity retention of 647 mA h g(-1) during the 50th cycle at 0.1 A g(-1), which is by far the best for SnS2, suggesting that nanosheet morphology is beneficial to improve cycling stability in addition to rate capability. The SnS2 nanosheets also show encouraging performance in a full cell with a Na3V2(PO4)3 cathode. In addition, the sodium storage mechanism is investigated by ex situ XRD coupled with high-resolution TEM. The high specific capacity, good rate capability, and cycling durability suggest that SnS2 nanosheets have great potential working as anodes for high-performance SIBs.

Electrocatalytic water splitting for hydrogen production is an appealing way to reduce carbon emissions and generate renewable fuels. This promising process, however, is limited by its sluggish reaction kinetics and high‐cost catalysts. Construction of low‐cost and high‐performance non‐noble metal‐based catalysts have been one of the most effective approaches to address these grand challenges. Notably, the electronic structure tuning strategy, which could subtly tailor the electronic states, band structures, and adsorption ability of the catalysts, has become a pivotal way to further enhance the electrochemical water splitting reactions based on non‐noble metal‐based catalysts. Particularly, heteroatom‐doping plays an effective role in regulating the electronic structure and optimizing the intrinsic activity of the catalysts. Nevertheless, the reaction kinetics, and in particular, the functional mechanisms of the hetero‐dopants in catalysts yet remains ambiguous. Herein, the recent progress is comprehensively reviewed in heteroatom doped non‐noble metal‐based electrocatalysts for hydrogen evolution reaction, particularly focus on the electronic tuning effect of hetero‐dopants in the catalysts and the corresponding synthetic pathway, catalytic performance, and activity origin. This review also attempts to establish an intrinsic correlation between the localized electronic structures and the catalytic properties, so as to provide a good reference for developing advanced low‐cost catalysts.

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2D black phosphorus (BP) is one promising electrocatalyst toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalysis. The too strong adsorption of oxygen intermediates during OER, while the too weak adsorption of hydrogen intermediate during HER, however, greatly compromise its practical water splitting applications with overpotentials as high as 450 mV for OER and 420 mV for HER to achieve 10 mA cm−2 under alkaline conditions. Herein, by rationally introducing the nanosized iridium (Ir) modifier together with optimized exposing surface toward electrolytes, an efficient Ir‐modified BP electrocatalyst with much favorable adsorption energies toward catalytic intermediates possesses an outstanding pH‐universal water splitting performance, surpassing the nearly all reported BP‐based catalysts and the commercial noble‐metal catalysts. The Ir‐modified BP catalyst with the optimized exposed surfaces only requires an overall cell voltage of 1.54 and 1.57 V to achieve 10 mA cm−2 in acidic and alkaline electrolysers, respectively. This design uncovers the potential applications of 2D BP in practical electrocatalysis fields via decreasing reaction intermediate adsorption energy barriers and promoting the interfacial electron coupling for heterostructured catalysts, and offers new insights into the surface‐dependent activity enhancement mechanism.

It has been well recognized that the surface reconstruction of electrocatalysts at the initial stage in the form of phase transitions, defect migrations, valence regulations, etc., plays a critical role in generating real, surface active catalytic centers and achieving steady surface reactions. It is also expected that a low activation energy barrier for initiating surface reconstruction is crucial for rapid and stable electrochemical catalysis. Despite this, the surface reconstruction kinetics and their effects on catalytic reactions have been rarely investigated. Herein, using phase modulated polymorphic cobalt‐based catalysts with tailorable nitrogen‐metal bonds through a cationic molybdenum‐substitution strategy, real‐time X‐ray photoelectron spectroscopy (XPS) structural monitoring of the surface chemical state evolution during the catalytic reaction is performed to track the initial surface reconstruction kinetics during the alkaline oxygen evolution reaction (OER). It is concluded that the molybdenum‐modulated cobalt‐based nanocatalyst can be tuned with favorable initial surface reconstruction and stabilized active centers to reach optimized OER catalysis, accompanied by a low onset overpotential of only 210 mV and a favorable overpotential at 10 mA cm–2 of 290 mV, outperforming the commercial, noble‐metallic RuO2 catalyst. This study thus provides new conceptual insights into rationally regulating the initial surface reconstruction kinetics for high‐performance electrocatalysis reactions.