Mn-based aqueous zinc-ion batteries (ZIBs) are promising candidate for large-scale rechargeable energy storage because of easy fabrication, low cost, and high safety. Nevertheless, the commercial application of Mn-based cathode is hindered by the challenging issues of low rate capability and poor cyclability. Herein, a manganese–vanadium hybrid, K–V2C@MnO2 cathode, featured with MnO2 nanosheets uniformly formed on a V2CTX MXene surface, is elaborately designed and synthesized by metal–cation intercalation and following in situ growth strategy. Benefiting from the hybrid structure with high conductivity, abundant active sites, and the synergistic reaction of Mn2+ electrodeposition and inhibited structural damage of MnO2, K–V2C@MnO2 shows excellent electrochemical performance for aqueous ZIBs. Specifically, it presents the high specific capacity of 408.1 mAh g–1 at 0.3 A g–1 and maintains the specific capacity of 119.2 mAh g–1 at a high current density of 10 A g–1 in a long-term cycle of up to 10000 cycles. It is superior to almost all reported Mn-based cathodes for ZIBs in the aqueous electrolyte. The superior electrochemical performance suggests that the Mn-based cathode materials designed in this work can be a rational approach to be applied for high-performance ZIBs cathodes.

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Screening and developing highly efficient electrodes is key to large-scale water electrolysis. The practical industrial electrode should fulfill several criteria of high activity, structural stability, and fast bubble evolution at a large current density. In this study, a novel monolithic 3D hollow foam electrode that can achieve the requirements of large current density water electrolysis is developed and fabricated through a simple electroless plating-calcination strategy. This strong 3D Ni-Mo-B hollow foam electrode can withstand a pressure of 2.37 MPa and exhibits high electrochemical surface area, high conductivity, and low gas transfer resistance, drastically boosting its catalytic performance. It affords 50 mA cm -2 at overpotentials of only 68 mV for hydrogen evolution reaction and 293 mV for oxygen evolution reaction and can survive at a large current density of 5 A cm -2 while maintaining its structure and performance in 1.0 m KOH. The advantages of facile preparation, high mechanical strength, high gas mass transfer ability, and excellent performance enable this structure to be a potential electrode, active substrate, or 3D catalyst in many fields.

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