RESUMEN
There is an urgent need to design practical aqueous rechargeable batteries (ARBs) with high energy density and long cycle life, using state-of-the-art cathode materials with low toxicity and environmental friendly nature. In virtue of the stable discharge potential and high energy density, silver (Ag) presents a huge perspective in the field of aqueous batteries. Herein, the paradigm of a novel core-shell Ag@Cu structure in situ Cu porous nanowire array skeleton (Ag@Cu NWA) is designed as the efficient cathode of an ARB. Benefiting from the ultrathin metal Ag shell (â¼7 nm) and the high-conductivity metal Cu core, along with the robust porous nanowire framework, the as-obtained Ag@Cu NWA cathode integrates the features of maximal utilization of the active material, superior charge transfer, and exceptional electrolyte accessibility, exhibiting a considerable capacity of 1.79 mA h cm-2 (458 mA h g-1: 92.3% of theoretical capacity) and remarkable cycling stability (83.6% retention after 5000 cycles). Furthermore, a well-designed aqueous rechargeable Ag//Bi full cell is fabricated using the Ag@Cu NWA cathode, achieving high capacity (1.57 mA h cm-2 at 2 mA cm-2) with excellent rate performance (92.9% at 20 mA cm-2) and an admirable energy density of 16.96 mW h cm-3. This work puts forward a prospective strategy to construct viable new types of ARB materials based on multimetal nanocomposites, showing great potential for practical electronic devices.
RESUMEN
Designing highly efficient electrocatalysts for oxygen evolution reaction (OER) plays a key role in the development of various renewable energy storage and conversion devices. In this work, we developed metallic Co4N porous nanowire arrays directly grown on flexible substrates as highly active OER electrocatalysts for the first time. Benefiting from the collaborative advantages of metallic character, 1D porous nanowire arrays, and unique 3D electrode configuration, surface oxidation activated Co4N porous nanowire arrays/carbon cloth achieved an extremely small overpotential of 257â mV at a current density of 10â mA cm(-2), and a low Tafel slope of 44â mV dec(-1) in an alkaline medium, which is the best OER performance among reported Co-based electrocatalysts to date. Moreover, in-depth mechanistic investigations demonstrate the active phases are the metallic Co4N core inside with a thin cobalt oxides/hydroxides shell during the OER process. Our finding introduces a new concept to explore the design of high-efficiency OER electrocatalysts.