Iodine ion modification enables Ag nanowire film with improved carrier transport properties and stability as high-performance transparent conductor

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.

Bottom-up fabrication of three-dimensional nanoporous gold from Au nanoparticles using nanowelding

Three-dimensional(3D)nanoporous gold(NPG)shows promising applications in various fields.However,its most common fabrication strategy(i.e.,dealloying)faces the problems of high energy consumption,resource waste,the use of corrosive solvent,and residue of the sacrificial component.Here,we report a general bottom-up nanowelding strategy to fabricate high-purity NPG from Au nanoparticles(NPs),accomplished via interfacial self-assembly of the Au NPs into monolayer Au NP film,its subsequent layer-by-layer transfer onto a solid substrate,and direct current(DC)nanowelding.We show that the DC nanowelding process can gradually evolve the layered Au NP film into NPG at low temperatures within 10 s,while not damaging their spherical structure.This is because during the nanowelding,electrons are preferred to be localized at the high-resistance NP/NP junctions,whose electrostatic repulsion in turn strengthens their surface atom diffusion to initiate a mild solid-state diffusion nanowelding.Furthermore,when using differently sized Au NPs as the starting building blocks,this strategy allows readily tuning the thickness,ligament size,and pore size,thereby offering great flexibility to create functional porous nanomaterials,e.g.,electrocatalyst for methanol electrooxidation.Surely,low-temperature nanowelding can play a role for the production of diverse nanoporous materials from other NPs beyond Au NPs.