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Recently emerged electronic skins with applications in on-body sensing and human-machine interfaces call for the development of high-performance skin-like electrodes. In this work, we report a highly robust, transparent, and breathable epidermal electrode composed of a scaffold-reinforced conductive nanonetwork (SRCN). Solution-dispersed Ag nanowires, through facile vacuum filtration, are embedded into a scaffold made of polyamide nanofibers. Optical transmittance of 84.9% at 550 nm wavelength is achieved at a significantly low sheet resistance of 8.2 Ω sq. The resistance of the SRCN only slightly increases by less than 0.1% after being bent for 3000 cycles at the maximum curvature of 300 m and by less than 1.5% after being dipped in saline solution for 2500 cycles. The excellent robustness is attributed to the reinforcement from the nanofiber-based scaffold as a backbone that maintains the connections among the Ag nanowires by undertaking most of the loaded stress. The SRCN not only forms tight and conformal bonding with the target surface but also allows the evaporation of perspiration, making it suitable as an epidermal electrode for long-time use. Furthermore, fine and clean-cut circuit patterns with a line width on the micrometer scale can be readily prepared, paving the way for fabricating sophisticated functional electronic skins.

Skin sensors are of paramount importance for flexible wearable electronics, which are active in medical diagnosis and healthcare monitoring. Ultrahigh sensitivity, large measuring range, and high skin conformability are highly desirable for skin sensors. Here, an ultrathin flexible piezoresistive sensor with high sensitivity and wide detection range is reported based on hierarchical nanonetwork structured pressuresensitive material and nanonetwork electrodes. The hierarchical nanonetwork material is composed of silver nanowires (Ag NWs), graphene (GR), and polyamide nanofibers (PANFs). Among them, Ag NWs are evenly interspersed in a PANFs network, forming conductive pathways. Also, GR acts as bridges of crossed Ag NWs. The hierarchical nanonetwork structure and GR bridges of the pressure-sensitive material enable the ultrahigh sensitivity for the pressure sensor. More specifically, the sensitivity of 134 kPa −1 (0−1.5 kPa) and the low detection of 3.7 Pa are achieved for the pressure sensor. Besides, the nanofibers act as a backbone, which provides effective protection for Ag NWs and GR as pressure is applied. Hence, the pressure sensor possesses an excellent durability (>8000 cycles) and wide detection range (>75 kPa). Additionally, ultrathin property (7 μm) and nanonetwork structure provide high skin conformability for the pressure sensor. These superior performances lay a foundation for the application of pressure sensors in physiological signal monitoring and pressure spatial distribution detection.

Solar-driven CO 2 photoreduction is attractive to produce usable fuels and valueadded chemicals. However, conventional strategies suffer from low activity and/or expense of sacrificial reagents. Here, the first example of CO 2 reduction to CO integrated with an oxidative organic synthesis of 1-phenylethanol to pinacols under solar light is reported. This strategy, making full utilization of photogenerated electrons and holes in redox reactions, provides the exact answer toward cost-effective CO 2 photoreduction.