Healable conductive materials have received considerable attention. However, their practical applications are impeded by low electrical conductivity and irreversible degradation after breaking/healing cycles. Here we report a highly conductive completely reversible electron tunneling-assisted percolation network of silver nanosatellite particles for putty-like moldable and healable nanocomposites. The densely and uniformly distributed silver nanosatellite particles with a bimodal size distribution are generated by the radical and reactive oxygen species-mediated vigorous etching and reduction reaction of silver flakes using tetrahydrofuran peroxide in a silicone rubber matrix. The close work function match between silicone and silver enables electron tunneling between nanosatellite particles, increasing electrical conductivity by~5 orders of magnitude (1.02×10 3 Scm −1) without coalescence of fillers. This results in~100% electrical healing efficiency after 1000 breaking/healing cycles and stability under water immersion and 6-month exposure to ambient air. The highly conductive moldable nanocomposite may find applications in improvising and healing electrical parts.

The dependence of the electrical resistance on materials’ geometry determines the performance of conductive nanocomposites. Here, we report the invariable resistance of a conductive nanocomposite over 30% strain. This is enabled by the in situ–generated hierarchically structured silver nanosatellite particles, realizing a short interparticle distance (4.37 nm) in a stretchable silicone rubber matrix. Furthermore, the barrier height is tuned to be negligible by matching the electron affinity of silicone rubber to the work function of silver. The stretching results in the electron flow without additional scattering in the silicone rubber matrix. The transport is changed to quantum tunneling if the barrier height is gradually increased by using different matrix polymers with smaller electron affinities, such as ethyl vinyl acetates and thermoplastic polyurethane. The tunneling current decreases with increasing strain, which is accurately described by the Simmons approximation theory. The tunable transport in nanocomposites provides an advancement in the design of stretchable conductors.

Silver has long been employed as an electrically conductive component, and morphology-dependent properties have been actively investigated. Here we present a novel scalable synthesis method of flower-shaped silver nanoparticles (silver nanoflowers, Ag NFs). The preferential affinity of citrate molecules on (111) surface of silver enabled spontaneous anisotropic growth of Ag NFs (bud size: 250~580 nm, single crystalline petal thickness: 9~22 nm) with high reproducibility and a high yield of >99.5%. The unique hierarchical structure resulted in coalescence of petals over 80~120 °C which was practically employed in conductive inks to construct percolation pathways among Ag NFs. The ink with only 3 wt% of Ag NFs provided two orders of magnitude greater conductivity (1.008 × 105 Scm−1), at a low curing temperature of 120 °C, compared with the silver nanoparticle ink with a much higher silver concentration (50 wt%). This extraordinary property may provide an excellent opportunity for Ag NFs for practical applications in printable and flexible electronics.

Electrides have received considerable attention due to their exotic properties. However, the high reactivity with oxygen and moisture immediately decomposed electrides in an ambient air environment. Here we passivated dicalcium nitride electride (Ca 2 N:e − ) with silver via a wet chemical approach (Ag-Ca 2 N), significantly enhancing stability up to 17 min at room temperature in an ambient air environment. The Ca 2 N:e − was employed as a reducing agent due to the low work function (2.6 eV), high mobility, and high electron concentration facilitating electron transfer to Ag + ion in an aprotic cosolvent. Moreover, the noble metal surface passivation (thickness: 55 nm) was achieved with negligible increase in work function of Ag-Ca 2 N (2.78 eV). The optimized molar ratio of AgNO 3 /Ca 2 N:e − was 0.5. The enhanced stability of Ag-Ca 2 N in organic reaction medium enabled successful aldol condensation reaction outside the glovebox, with a high α,βunsaturated ketone yield of 75.4%, without involving environmentally harmful strong acid or base. The enhanced stability and low work function may realize practical economic applications of Ag-Ca 2 N.

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