KCS

Most importantly, chemical free and noble metal free design of electrocatalysts is highly required. First time we have applied chemical free strategy to design highly reactive sub-2 nm Co3O4 ultra-small nanoparticles (USNPs) and active edges having 2dimensional fibrous carbon wrapped Co3O4 ultra-small nanoparticles (Co3O4 USNPs@FC). The strategy is the single green waste source (fibrous orange peel) for two utilities and multi applications (1+2+m) with zero waste generation. The green solvent with functional groups plays a crucial role to obtained Co3O4 ultra-small nanoparticles, which were further intertwined with the plethora of active sites have fibers carbon. Due to pivotal traits like high surface area, mesoporosity, and lone pair of electrons in the structure of Co3O4 USNPs@FC shows an excellent electrocatalyst activity for oxygen evaluation reaction (OER) with an overpotential of 390 mV at 10 mA cm-2 and high stability under seawater. This synthesis strategy unveils to create eco-friendly nanostructures for energy conversion from various aqueous systems.