Developing low-cost single-atom catalysts (SACs) with high-density active sites for oxygen reduction/evolution reactions (ORR/OER) are desirable to promote the performance and application of metal-air batteries. Herein, the Fe nanoparticles are precisely regulated to Fe single atoms supported on the waste biomass corn silk (CS) based porous carbon for ORR and OER. The distinct hierarchical porous structure and hollow tube morphology are critical for boosting ORR/OER performance through exposing more accessible active sites, providing facile electron conductivity, and facilitating the mass transfer of reactant. Moreover, the enhanced intrinsic activity is mainly ascribed to the high Fe single-atom (4.3 wt.%) loading content in the as-synthesized catalyst. Moreover, the ultra-high N doping (10 wt.%) can compensate the insufficient OER performance of conventional FeNC catalysts. When as-prepared catalysts are assembled as air-electrodes in flexible Zn-air batteries, they perform a high peak power density of 101 mW cm −2 , a stable discharge-charge voltage gap of 0.73 V for >44 h, which shows a great potential for Zinc-air battery. This work provides an avenue to transform the renewable low-cost biomass materials into bifunctional electrocatalysts with high-density single-atom active sites and hierarchical porous structure.
Development of monodispersed crystalline nanoparticles with previously unavailable spherical shapes continues to be a constant theme in a wide range of areas but remains a challenge. On the basis of in situ vulcanization strategy and density functional calculations, we show that the shape evolution of uneven metal oxide nanoparticles can be used to achieve highly crystalline monodispersed oxide nanospheres by taking advantage of the unique lattice mismatch at interfaces between closely packed molybdenum dioxide and layered molybdenum sulfides. The monodispersed MoO 2 nanospheres together with the adhered ultrathin MoS 2 nanosheets show a surprisingly high photoreduction ability of concentrated Cr(VI), superior to those ever reported for MoO 2 -or MoS 2 -containing materials under visible and near-infrared light, most likely due to the merits as represented by the metallic character, high density carrier, near-infrared local surface plasma resonance effect, and enhanced interfacial interactions. In this study, the merits of MoS 2 /MoO 2 are fully utilized and outstanding photocatalytic reduction performances of Cr(VI) are achieved, which opens up exciting prospects for its practical application in photocatalysis. The methodology reported here may provide more opportunities to explore functions of monodispersed crystalline oxide nanospheres.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.