A three-dimensional graphene network (3DGN) grown on nickel foam is an excellent template for the synthesis of graphene-based composite electrodes for use in supercapacitors. Ni(OH) 2 nanosheets coated onto single-crystal Ni 3 S 2 nanorods grown on the surface of the 3DGN (referred to as the Ni 3 S 2 @Ni(OH) 2 / 3DGN) are synthesized using a one-step hydrothermal reaction. SEM, TEM, XRD and Raman spectroscopy are used to investigate the morphological and structural evolution of the Ni 3 S 2 @Ni(OH) 2 /3DGN. Detailed electrochemical characterization shows that the Ni 3 S 2 @Ni(OH) 2 /3DGN exhibits high specific capacitance (1277 F g À1 at 2 mV s À1 and 1037.5 F g À1 at 5.1 A g À1) and areal capacitance (4.7 F cm À2 at 2 mV s À1 and 3.85 F cm À2 at 19.1 mA cm À2) with good cycling performance (99.1% capacitance retention after 2000 cycles).

Conductive polymer hydrogels are receiving considerable attention in applications such as soft robots and human-machine interfaces. Herein, a transparent and highly ionically conductive hydrogel that integrates sensing, UV-filtering, water-retaining, and anti-freezing performances is achieved by the organic combination of tannic acid-coated hydroxyapatite nanowires (TA@HAP NWs), polyvinyl alcohol (PVA) chains, ethylene glycol (EG), and metal ions. The highly ionic conductivity of the hydrogel enables tensile strain, pressure, and temperature sensing capabilities. In particular, in terms of the hydrogel strain sensors based on ionic conduction, it has high sensitivity (GF = 2.84) within a wide strain range (350%), high linearity (R 2 = 0.99003), fast response (≈50 ms) and excellent cycle stability. In addition, the incorporated TA@HAP NWs act as a nano-reinforced filler to improve the mechanical properties and confer a UV-shielding ability upon the hydrogel due to its size effect and the characteristics of absorbing ultraviolet light waves, which can reflect and absorb short ultraviolet rays and transmit visible light. Meanwhile, owing to the water-locking effect between EG and water molecules, the hydrogel exhibits freezing resistance at low temperatures and moisture retention at high temperatures. This biocompatible and multifunctional conductive hydrogel provides new ideas for the design of novel ionic skin devices.

Transition metal catalysts are known to activate persulfate, but the properties that govern the intrinsic activity of these catalysts are still unknown. Here, we developed a series of catalysts with transition metals anchored on carbon nanotubes (denoted M–N–CNTs, where M = Co, Fe, Mn, or Ni) containing single-atom M–N moieties, to activate peroxymonosulfate for the efficient nonradical oxidation of sulfamethoxazole. The spin state of M–N–CNTs strongly determined their catalytic activity. A large effective magnetic moment with a high spin state (e.g., Co–N) favored the overlap of d orbitals with oxygen-containing adsorbates (such as peroxo species) on metal active sites and promoted electron transfer, which facilitated peroxymonosulfate adsorption and enhanced the oxidation capacity of the reactive species. These findings advance the mechanistic understanding of transition metal-mediated persulfate activation and inform the development of efficient spintronic catalysts for environmental applications.

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