CoNi(OH)₂ Nanoflowers on V₂O₅ for Energy Storage and Electrocatalysis

High Resolution Image Download MS PowerPoint Slide Transition metal-based binary hydroxides (BHs) have been considered promising electrodes for supercapacitors (SCs) and oxygen evolution reactions (OERs) due to their outstanding electrical properties and high conversion efficiency. However, the poor electrical conductivity hinders their further practical applications in energy storage and conversion. Herein, this study describes a two-step solution method for synthesizing V 2 O 5 @CoNi(OH) 2 BH nanoflowers (VCNBH NFs). The use of ultrathin 3D flower-like CNBH nanosheet arrays, induced by 2-methyl imidazole on V 2 O 5 nanorods (NRs), enhances their performance as a bifunctional electrocatalytic system for OER and SCs in alkaline environments. The synergy between V 2 O 5 NRs and CNBH NFs facilitates the adsorption/desorption of intermediates on VCNBH NFs, resulting in a large surface area and excellent electrocatalytic properties. VCNBH NF electrode materials demonstrate a remarkable specific capacitance and capacity of 1050 C g – 1 (292 mAh/g) at a current density of 0.5 A g – 1 in a three-electrode system, retaining 96% of their initial capacitance after 20,000 charge–discharge cycles. An asymmetrical device achieves a power and energy density of 400 W kg –1 and 93 Wh kg –1, respectively. Moreover, VCNBH NFs demonstrate excellent OER performance, requiring just 225 mV to reach 10 mA cm –2 in 1.0 M KOH, with a low Tafel slope of 50 mV dec –1, indicating efficient reaction kinetics and outstanding catalytic durability. Density functional theory (DFT) calculations were employed to investigate the electronic structure, revealing that interface engineering between V 2 O 5 and CoNi(OH) 2 induces favorable electronic states that contribute to enhanced electrochemical activity. This study successfully establishes the effective performance of multifunctional electrochemical energy materials.