Designing electrocatalysts with high-performance for both reduction and oxidation reactions faces severe challenges. Here, the uniform and ultrasmall (~3.4 nm) high-entropy alloys (HEAs) Pt18Ni26Fe15Co14Cu27 nanoparticles are synthesized by a simple low-temperature oil phase strategy at atmospheric pressure. The Pt18Ni26Fe15Co14Cu27/C catalyst exhibits excellent electrocatalytic performance for hydrogen evolution reaction (HER) and methanol oxidation reaction (MOR). The catalyst shows ultrasmall overpotential of 11 mV at the current density of 10 mA cm−2, excellent activity (10.96 A mg−1Pt at −0.07 V vs. reversible hydrogen electrode) and stability in the alkaline medium. Furthermore, it is also the efficient catalyst (15.04 A mg−1Pt) ever reported for MOR in alkaline solution. Periodic DFT calculations confirm the multi-active sites for both HER and MOR on the HEA surface as the key factor for both proton and intermediate transformation. Meanwhile, the construction of HEA surfaces supplies the fast site-to-site electron transfer for both reduction and oxidation processes.

Despite high-energy density and low cost of the lithium-sulfur (Li-S) batteries, their commercial success is greatly impeded by their severe capacity decay during long-term cycling caused by polysulfide shuttling. Herein, a new phase engineering strategy is demonstrated for making MXene/1T-2H MoS 2 -C nanohybrids for boosting the performance of Li-S batteries in terms of capacity, rate ability, and stability. It is found that the plentiful positively charged S-vacancy defects created on MXene/1T-2H MoS 2 -C, proved by high-resolution transmission electron microscopy and electron paramagnetic resonance, can serve as strong adsorption and activation sites for polar polysulfide intermediates, accelerate redox reactions, and prevent the dissolution of polysulfides. As a consequence, the novel MXene/1T-2H MoS 2 -C-S cathode delivers a high initial capacity of 1194.7 mAh g −1 at 0.1 C, a high level of capacity retention of 799.3 mAh g −1 after 300 cycles at 0.5 C, and reliable operation in soft-package batteries. The present MXene/1T-2H MoS 2 -C becomes among the best cathode materials for Li-S batteries.

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Nitrogen, phosphorus and oxygen tri-doped porous graphite carbon@oxidized carbon cloth electrodes exhibit excellent activity and durability for full water splitting at all pH values.

Despite its very high capacity (4200 mAh g −1 ), the widespread application of the silicon anode is still hampered by severe volume changes (up to 300%) during cycling, which results in electrical contact loss and thus dramatic capacity fading with poor cycle life. To address this challenge, 3D advanced Mxene/Si-based superstructures including MXene matrix, silicon, SiO x layer, and nitrogen-doped carbon (MXene/ Si@SiO x @C) in a layer-by-layer manner were rationally designed and fabricated for boosting lithium-ion batteries (LIBs). The MXene/Si@SiO x @C anode takes the advantages of high Li + ion capacity offered by Si, mechanical stability by the synergistic effect of SiO x , MXene, and N-doped carbon coating, and excellent structural stability by forming a strong Ti−N bond among the layers. Such an interesting superstructure boosts the lithium storage performance (390 mAh g −1 with 99.9% Coulombic efficiency and 76.4% capacity retention after 1000 cycles at 10 C) and effectively suppresses electrode swelling only to 12% with no noticeable fracture or pulverization after long-term cycling. Furthermore, a soft package full LIB with MXene/Si@SiO x @C anode and Li[Ni 0.6 Co 0.2 Mn 0.2 ]O 2 (NCM622) cathode was demonstrated, which delivers a stable capacity of 171 mAh g −1 at 0.2 C, a promising energy density of 485 Wh kg −1 based on positive active material, as well as good cycling stability for 200 cycles even after bending. The present MXene/Si@SiO x @C becomes among the best Si-based anode materials for LIBs.

appeared as a promising route due to its simplicity, low cost, zero greenhouse gas emission, and high energy conversion efficiency. [13][14][15][16][17][18][19] Therein, the basic hydrogen evolution reaction (HER) is deemed to be a more valuable process than acidic oxygen evolution reaction due to the lack of electrocatalysts for the acidic oxygen evolution reaction. Therefore, developing HER electrocatalysts with high activity and superior stability in alkaline media is highly desirable for electrochemical water splitting because the basic HER rate is 2-3 orders of magnitude lower than that in acidic solutions. [20][21][22][23][24][25][26][27][28][29][30] Currently, state-of-the-art HER electrocatalysts in alkaline solutions are precious Pt-based materials, which extremely limit their widespread commercialization. Recently, great efforts have been devoted to enhancing the performance of inexpensive electrocatalysts to replace the precious Pt-based catalysts. Among the potential catalysts, transition metal nitrides, especially nickel-based mixed metal compounds, have been widely demonstrated as highly active HER catalysts in alkaline solution owing to their special properties such as low electrical resistance, superior water dissociation kinetics, and good corrosion resistance. [31][32][33][34] However, it is still a great challenge to design strongly coupled transition metal nitrides/C hybrid nanocage (NiCoN/C nanocage) structures with outstanding performance for basic HER. Designing non-precious-metal catalysts with comparable mass activity to state-of-the-art noble-metal catalysts for the hydrogen evolution reaction (HER) in alkaline solution still remains a significant challenge. Herein a new strongly coupled nickel-cobalt nitrides/carbon complex nanocage (NiCoNzocage) is rationally designed via chemical etching of ZIF-67nanocubes with Ni(NO 3 ) 2 under sonication at room temperature, following nitridation. The as-prepared strongly coupled NiCoN/C nanocages exhibit a mass activity of 0.204 mA µg −1 at an overpotential of 200 mV for the HER in alkaline solution, which is comparable to that of commercial Pt/C (0.451 mA µg −1 ). The strongly coupled NiCoN/C nanocages also possess superior stability for the HER with negligible current loss under the overpotentials of 200 mV for 10 h. Density functional theory (DFT) calculations reveal that the excellent HER performance under alkaline condition arises from the robust Co 2+ →Co 0 transformation achieved by strong (Ni, Co)Nbonding-induced efficient d-p-d coupled electron transfer, which is a key for optimal initial water adsorption and splitting. The high degree of amorphization urges the C-sites to be an electron-pushing bath to promote the interlayer/sites electron-transfer with loss of the orbital-selection-forbidden-rule, which uniformly boosts the surface catalytic activities up to a high level independent of the individual surface active sites. ElectrocatalysisThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

High‐entropy alloys (HEAs) have attracted widespread attention in electrocatalysis due to their unique advantages (adjustable composition, complex surface, high tolerance, etc.). They allow for the formation of new and tailorable active sites in multiple elements adjacent to each other, and the interaction can be tailored by rational selection of element configuration and composition. However, it needs to be further explored in catalyst design, the interaction of elements, and the determination of active sites. This review article focuses on the important progress for multi‐sites electrocatalysis in HEAs. The classification is done on the basis of catalytic reaction, including hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, alcohol oxidation reaction, carbon dioxide reduction reaction, and nitrogen reduction reaction. Based on experiments and theories, a more in‐depth exploration of the high catalytic activity of HEAs will be conducted, including the selection of elements (the special role of each element in catalysis) and the multi‐sites effect. This review can provide the basis for the element selection and design of HEAs in some reactions, to adjust the compositions of HEAs to improve their intrinsic activity. Furthermore, the remaining challenges and future directions for promising research fields are also provided.