Synergy of zero-dimensional carbon dots decoration on the one-dimensional architecture of Ag-doped V₂O₅ for supercapacitor and overall water-splitting applications

The production of renewable energy sources and energy storage devices is crucial in addressing current global energy challenges. Hydrogen energy is a clean form of energy that can be produced without any harmful byproducts. For this purpose, nanorods of vanadium oxide (V2O5) and silver-doped vanadium oxide (Ag/V2O5) were synthesized by hydrothermal route. The carbon dots decorated silver doped vanadium oxide (Ag/V2O5@C) was fabricated using an ultrasonication approach. Various physio-chemical techniques were used to characterize the fabricated samples. The synthesized materials were employed as electrodes and electrocatalysts for supercapacitor and water-splitting applications. Cyclic voltammetry and cyclic charge-discharge experiments were performed, and results showed that Ag/V2O5@C exhibited 936 Fg(-1) specific capacitance at 5 mVs(-1) and 977 s discharge time. The charge transfer resistance was calculated via electrochemical impedance spectroscopy and Ag/V2O5@C showed a lower charge transfer resistance than other prepared materials. At 10 mAcm(-2), Ag/V2O5@C exhibited lower overpotential of 126 mV and 388 mV for hydrogen evolution (HER) and oxygen evolution reactions (OER) respectively. The lower tafel slope of 81 mV dec(-1) and 71 mV dec(-1) was attributed to the Ag/V2O5@C for HER and OER respectively. Ag/V2O5@C showed higher reaction kinetics due to the fast rate of charge transfer, low resistance, high conductivity, and greater active sites provided by the carbon dots for electrocatalytic reaction. So, Ag/V2O5@C can be employed as an effective electrocatalyst and electrode material for electrochemical applications.