Needle-like ZnO nanorods (ZnO-NRs)/Ag nanoparticles (Ag-NPs) heterostructures with tunable silver contents have been successfully designed and constructed via a two-step hydrothermal approach on zinc foil. The as-fabricated heteroarchitectured composite was Ag-NPs with a size range about 30 to 50 nm in diameter assembled uniformly on the surface of needle-like ZnO-NRs, several micrometers long and about 480 nm wide near the half height of the nanorods. Through the variation of the reactant concentration such as silver nitrate, the silver content on the ZnO-NRs can be controllably tuned, which further greatly affected the photocatalytic performance of the decomposition of a representative dye pollutant of rhodamine B, and there is an optimum amount of secondary Ag-NPs. This facile method developed here also can be extended to construct other ZnO-based noble metal or semiconductor heterostructures on zinc substrates.

Developing a high‐rate and stable battery‐type anode to match the capacitor‐type cathode is a critical issue for potassium ion capacitors (PICs). Surface‐redox pseudocapacitive materials can meet this demand due to their fast surface Faradaic reaction kinetics and superior structure stability during charging–discharging. Herein, a free‐standing anode by growing VN particle‐composed nanosheets on carbon fibers (VN@CFs) is developed. The VN@CFs is endowed with high reversible capacity of 245.8 mA h g–1 at 0.05 A g–1, high rate performance of 102.7 mA h g–1 at 6.0 A g–1, and long‐term stability. Based on the in situ XRD, ex situ XPS and TEM characterizations, and density functional theory calculations, it is proved that the potassium storage of VN derives from a surface‐redox pseudocapacitive mechanism between VN and K+, rather than an intercalation or conversion reaction. As expected, the as‐assembled PICs based on the VN@CFs anode show an ultrahigh power output of 10.9 kW kg–1 when keeping an energy density of 49.2 Wh kg–1 and excellent capacity retention of 86.8% after 15000 cycles.

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The development of flexible supercapacitors is highly desired for electrode materials with good flexibility and a high specific surface area. The electrospun carbon fiber membranes (CFMs) have the possibility of being used as flexible electrodes due to their one-dimensional fiber structure. The pristine CFMs generally have poor porosity, and the activation process is of the essence. However, the conventional blending activation process will produce an uneven pore distribution and destroy the fiber membrane structure, which is not conducive to maintaining the flexibility of CFMs and hindering the application in flexible supercapacitors. Herein, by treating the electrospun CFMs with KOH impregnation activation process, we have succeeded in making the activation of CFMs more uniform and avoiding the occurrence of local over-activation. On the premise of ensuring that the fiber structure of CFMs is not damaged, the specific surface area of activated CFMs (ACFMs) was increased to 2408 m 2 g -1 , and the mechanical flexibility of CFMs was well maintained. As a result, the optimal ACFMs delivers a specific capacitance of 289.2 F g -1 at a current density of 0.5 A g -1 in aqueous electrolyte and an energy density of 14.8 Wh kg -1 in neutral electrolyte. In addition, the flexible solid-state symmetric supercapacitor also shows excellent electrochemical performance, making it have great potential in energy storage applications for wearable, foldable, and portable electronic devices.