Ag nanowire (NW) film is the promising next generation transparent conductor. However, the residual long-chain polyvinylpyrrolidone (PVP, introduced during the synthesis of Ag NWs) layer greatly deteriorates the carrier transport capability of the Ag NW film and as well its long-term stability. Here, we report a one-step I⁻ ion modification strategy to completely replace the PVP layer with an ultrathin, dense layer of I⁻ ions, which not only greatly diminishes the resistance of the Ag NW film itself and that at interface of the Ag NW film and a functional layer (e.g., a current collect electrode) but also effectively isolates the approaching of corrosive species. Consequently, this strategy can simultaneously improve the carrier transport properties of the Ag NW film and its long-term stability, making it an ideal electric component in diverse devices. For example, the transparent heater and pressure sensor made from the I⁻-wrapped Ag NW film, relative to their counterparts made from the PVP-wrapped Ag NW film, deliver much improved heating performance and pressure sensing performance, respectively. These results suggest a facile post treatment approach for thin Ag NW film with improved carrier transport properties and long-term stability, thereby greatly facilitating its downstream applications.

The accomplishment of nanowelding typically requires the input of high energy, possibly causing appreciable damages to the brittle nanomaterial. Herein, we report an external field (EF, i.e., light, direct current (DC), and alternating current (AC))-strengthened Ostwald nanowelding (ONW) strategy to enable low-temperature nanowelding of Au nanoparticles (NPs) with nanoscale spacing in solution and propose an electron localization mechanism to understand it. We reveal that the EF-derived local electrons not only greatly strengthen the dissolution of surface atoms and the reduction of Au³⁺ ions dissolved, but also confine (together with ordered water molecules) the transport of Au³⁺ ions within the nanogap. Consequently, the electrochemical Ostwald ripening (OR) process of the Au NPs is actively strengthened, which, along with the local electron-strengthened surface atom diffusion (as a result of the strong electrostatic repulsion created), enables feasible ONW for solution processing of interdigital electrodes (IDEs) from Au NPs and high-performance transparent conductor (TC) from Ag nanowires (NWs). Our low-temperature nanowelding strategy offers an efficient interconnection technique for the processing of functional nanodevices from individual nanomaterials.

Capacitive deionization is an attractive approach to water desalination and treatment. To achieve efficient capacitative desalination, rationally designed electrodes with high specific capacitances, conductivities, and stabilities are necessary. Here we report the construction of a three-dimensional (3D) holey graphene hydrogel (HGH). This material contains abundant in-plane pores, offering efficient ion transport pathways. Furthermore, it forms a highly interconnected network of graphene sheets, providing efficient electron transport pathways, and its 3D hierarchical porous structure can provide a large specific surface area for the adsorption and storage of ions. Consequently, HGH serves as a binder-free electrode material with excellent electrical conductivity. Cyclic voltammetry (CV) measurements indicate that the optimized HGH can achieve specific capacitances of 358.4 F·g^-1 in 6 M KOH solution and 148 F·g^-1 in 0.5 M NaCl solution. Because of these high capacitances, HGH has a desalination capacity as high as 26.8 mg·g^-1 (applied potential: 1.2 V; initial NaCl concentration: ~5, 000 mg·L^-1).