In-situ formed hierarchical transition metal oxide nanoarrays with rich antisite defects and oxygen vacancies for high-rate energy storage devices

摘要

Developing transition metal oxides(TMOs)with high energy,power,and long cycle lifetime for elec-tric energy storage devices remains a critical challenge to date.Herein,we demonstrate a facile method that enables in-situ transformation of nickel cobalt oxide nanowire arrays(NiCoO NWA)into hierarchical nanowire-nanosheet arrays(ac-NiCoO NWSA)for enhanced energy storage properties.More specifically,the method leads to formation of atomically thin nanosheets(only 2.0 nm)and creates abundant an-tisite defects and oxygen vacancies.Owing to these merits,the as-prepared ac-NiCoO NWSA electrode exhibits over five-fold higher specific capacity,superior rate capability(up to 100 A/g),and excellent cy-cling stability of 10,000 cycles at 50 A/g in alkaline electrolyte compared to pristine NiCoO NWA.Density functional theory(DFT)simulations elucidate the electrochemical activity enhancement mechanism of the TMOs.Moreover,our method triggers similar structural reconstruction phenomenon on other TMOs including ZnCo-,CoMn-and ZnNiCo-oxides,proving the universality of the method.Our findings provide a general method towards simultaneously manipulating the micro-morphologies and defects of TMOs for advanced energy storage devices.