Photothermal devices and thermoelectric cells hold great promise for energy generation but integration of the two remains a considerable challenge in real-life power supply for sensors. Here, a novel photo-thermo-electric hydrogel (PTEH-Interlocking) was constructed by the synthesis of a photothermal layer on a thermoelectric hydrogel with the redox pair Fe(CN)63−/Fe(CN)64−. The smart design of using the oxidation of pyrogallic acid by Fe(CN)63− to construct the photothermal layer for photo-to-heat conversion protected the redox couple of the thermogalvanic ion pair from ultraviolet damage, as well as triggered the formation of an interlocking structure at the interface of the photothermal layer and the thermoelectric hydrogel. The as-prepared PTEH-Interlocking has shown a high Seebeck coefficient and rapid heat transfer, boosting the photo-thermo-electric conversion. As a demonstration of a practical application, the PTEH-Interlocking cells are successfully used as the energy supply for a mechanical sensor.
The rising demand for wearable zinc-air batteries encounters challenges in balancing electrochemical performance and mechanical resilience. Elastic carbon aerogels in air cathodes necessitate a metal content constraint of less than 3 wt.%, adversely impacting catalytic activity optimization. This study presents a novel fabrication method for fibrous carbon aerogels with high compressive resilience and extraordinary catalytic performance. An external layer of graphene shells and carbon nanotubes integrated onto the fibrous carbon matrix mitigates metallic species diffusion. This confinement ensures exceptional bi-catalytic activity for oxygen-involved redox reactions without compromising ultra-elasticity. With high cobalt content in the aerogel cathode, it exhibits minimal voltage gaps during charge–discharge cycles, showcasing unique zinc-cobalt-air hybrid battery characteristics. It sustains exceptional elasticity in repeated testing, achieving approximately 79.2% round-trip efficiency over a 60-h cycle test, underscoring its potential as a wearable energy storage device.
High-performance flexible and transparent chemical sensors are key to achieving wearable electronics. Graphene with high transmittance and electrical properties is a suitable material for flexible and transparent chemical sensors. However, graphene has low detectivity to chemical substances. Here, we report hybrid chemical sensors fabricated by introducing a highly flat and smooth metal–organic framework (MOF) on graphene. The graphene chemical sensors functionalized with MOF on SiO2/Si wafer exhibit 22 times higher sensitivity of 6.07 μA ppm−1 in detecting ethanol than that of pristine graphene transistors of 0.28 μA ppm−1 and a low detection limit of 1 ppm. Furthermore, a flexible transparent 7 × 7 chemical sensor array exhibits great driving stability after the bending cycles of 105 at a bending radius of 1.0 mm and shows sensitivity of 0.11 μA ppm−1. Our findings demonstrate an efficient way to improve the chemical sensing ability of graphene for application in wearable chemical sensors.
Natural polymers-based carbon electrodes have gained significant research attention for next-generation portable supercapacitors. Herein, present an environmentally benign and novel approach for the synthesis of N/S-Ox carbon material derived from natural polymers on gram scale. By capitalizing the synergistic effect of sulfonated lignin and amino-containing chitosan, this methodology produces a straightforward, low-budget, and scalable process. The incorporation of sulfonate motifs from lignin contributes to the formation of C-SOx moieties and multi-porous architecture with a high surface area. Simultaneously, amino groups in chitosan induce nitrogen doping, enhancing conductivity, and wettability. The resulting N/SOx carbon material exhibits a micro/meso-porous architecture, facilitating electrolyte diffusion, and demonstrating improved rate capability and pseudocapacitance via Faradaic redox reactions. The N/SOx carbon material showcases notable capacitance (392 F g−1 at 1 Ag−1) as compared with the reported carbon materials form biomass and outstanding cyclic stability (94.8% retention after 5000 cycles). By optimizing various chitosan mass ratios, the most effective N/SOx carbon material SNACM = S/N-doped activated carbon material (SNACM-2) was produced using a lignin: chitosan sample ratio of 1:2 for symmetric supercapacitors. Furthermore, the quasi-solid-state symmetric supercapacitors based on SNACM-2 exhibit an excellent specific capacitance of 142 F g−1 at 1 A g−1, coupled with outstanding flexibility. The SNACM-2 demonstrates a high-energy density of 9.8 W h kg−1 at a power density of 0.5 kW kg−1. This study presents a successful strategy for transforming low-valued, eco-friendly natural polymers into renewable, high-performance carbon materials for supercapacitors.