Bio-engineered hexagon-shaped Co3O4 nanoplates on deoxyribonucleic acid (DNA) scaffold: An efficient electrode material for an asymmetric supercapacitor and electrocatalysis application

Nanostructured mixed transition metal oxide spinels for supercapacitor applications

There have been numerous applications of supercapacitors in day-to-day life. Along with batteries and fuel cells, supercapacitors play an essential role in supplementary electrochemical energy storage technologies. They are used as power sources in portable electronics, automobiles, power backup, medical equipment, etc. Among various working electrode materials explored for supercapacitors, nanostructured transition metal oxides containing mixed metals are highly specific and special, because of their stability, variable oxidation states of the constituted metal ions, possibility to tune the mixed metal combinations, and existence of new battery types and extrinsic pseudocapacitance. This review presents the key features and recent developments in the direction of synthesis and electrochemical energy storage behavior of some of the recent morphology-oriented transition metal oxide and mixed transition metal oxide nanoparticles. We also targeted the studies on a few of the recently developed flexible and bendable supercapacitor devices based on these mixed transition metal oxides.

Plasma-Engineered N-CoOx Nanowire Array as a Bifunctional Electrode for Supercapacitor and Electrocatalysis

Surface engineering has achieved great success in enhancing the electrochemical activity of Co₃O₄. However, the previously reported methods always involve high-temperature calcination processes which are prone to induce agglomeration of the nanostructure, leading to the attenuation of performance. In this work, Co₃O₄ nanowires were successfully modified by a low-temperature NH₃/Ar plasma treatment, which simultaneously generated a porous structure and efficient nitrogen doping with no agglomeration. The modified N-CoO_x electrode exhibited remarkable performance due to the synergistic effect of the porous structure and nitrogen doping, which provided additional active sites for faradic transitions and improved charge transfer characteristics. The electrode achieved excellent supercapacitive performance with a maximum specific capacitance of 2862 mF/cm² and superior cycling retention. Furthermore, the assembled asymmetric supercapacitor (N-CoO_x//AC) device exhibited an extended potential window of 1.5 V, a maximum specific energy of 80.5 Wh/kg, and a maximum specific power of 25.4 kW/kg with 91% capacity retention after 5000 charge-discharge cycles. Moreover, boosted hydrogen evolution reaction performance was also confirmed by the low overpotential (126 mV) and long-term stability. This work enlightens prospective research on the plasma-enhanced surface engineering strategies.