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We have achieved the synthesis of dual-metal single atoms and atomic clusters that co-anchor on a highly graphitic carbon support. The catalyst comprises Ni 4 (and Fe 4 ) nanoclusters located adjacent to the corresponding NiN 4 (and FeN 4 ) single-atom sites, which is verified by systematic X-ray absorption characterization and density functional theory calculations. A distinct cooperation between Fe 4 (Ni 4 ) nanoclusters and the corresponding FeN 4 (NiN 4 ) atomic sites optimizes the adsorption energy of reaction intermediates and reduces the energy barrier of the potential-determining steps. This catalyst exhibits enhanced oxygen reduction and evolution activity and long-cycle stability compared to counterparts without nanoclusters and commercial Pt/C. The fabricated Zn−air batteries deliver a high power density and long-term cyclability, demonstrating their prospects in energy storage device applications.

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strain sensors have been favored by many researchers for their good flexibility, small size, light weight, and high conformability and have been initially explored for human health monitoring, human-computer interaction, and other fields. [7][8][9][10] The design and development of strain sensing materials are the core of flexible strain sensors. [11][12][13] With the concept of environmental protection and sustainable development deeply rooted, renewable, degradable, and natural fiber materials have become the more competitive materials to manufacture flexible strain sensors due to their low price, easy acquisition, and easy combination with textiles. [14][15][16] Natural fiber materials are mainly divided into cellulose fiber (cotton, fibrilia, and viscose) and protein fiber (wool and silk), which all show excellent softness and can be woven into yarn, nonwoven film, and 2D or 3D fabric with different structural characteristics. [17][18][19][20] The above materials can be directly carbonized or mixed with other conductive nanomaterials to construct flexible conductive networks. These green manufacturing materials have become an important trend to develop flexible strain sensors. [21][22][23] The carbonization temperature and time are the decisive factors for balancing the electrical conductivity and strain sensing performance of carbonized natural fiber materials. [24][25][26] Many studies found that although carbonized fibers exhibit excellent conductivity, they have a small strain range and high brittleness. Thus, they need to be combined with elastic polymers to improve their flexibility and strain capacity. [27][28][29] Original natural fiber materials can maintain excellent softness after they are combined with conductive nanomaterials, but they still exhibit major challenges, such as poor resilience, small strain range, poor wear resistance, and others. Therefore, they need to be combined with elastic polymers to improve the sensing performance. [30][31][32] The main polymer materials are polyurethane (TPU), polydimethylsiloxane (PDMS), and Ecoflex. The breaking elongation of the polymer determines the upper limit of the sensor strain range. The resilience, viscoelasticity, and fatigue resistance of the polymer are very important to the hysteresis, durability, and response speed of the sensor. The interfacial interaction between the polymer and conductive material affects the stability and sensitivity of the sensor. Conductive nanomaterials are diversiform, including carbon black (CB), carbon nanotubes (CNTs), graphene (GR), silver nanoparticles (AgNP), silver nanowires (AgNW), copper nanoparticles Flexible strain sensors with outstanding stretchability and sensitivity can be widely used in medical health, smart robot, intelligent garment, man-machine interaction, and other fields. The use of natural fibers enables a green manufacturing pathway to design strain sensors within the context of increasingly serious environmental pollution. Commercialized natural fibers, including cellulose fibers (cotton and ...