Hydrothermal assisted synthesis of novel NiSe₂/CuO nanocomposite: Extremely stable and exceptional energy storage performance for faradaic hybrid supercapacitors

This work portrays the synthesis of NiSe₂, CuO, and their nanocomposite NiSe₂/CuO (ST-1) via a cost-effective, simple, co-precipitation and hydrothermal method for the first time to explore its performance for sustainable faradaic hybrid supercapacitor. The electrochemical investigation revealed that the ST-1 electrode exhibits a remarkable capacitive performance (396 C g⁻¹) compared to their pure counterparts in capacity, e.g., NiSe₂ (330 C g⁻¹), CuO (265 C g⁻¹), and the lowest charge transfer resistance. Inspired by its durable energy storage performance, we further assembled the ST-1//AC/3M KOH faradaic hybrid supercapacitor, which effectively operates in a broad and stable voltage window of 1.6 V. The optimum voltage contributed to enhancing the capacitance of ST-1//AC/KOH faradaic hybrid supercapacitor up to 120 F/g at 1 A g^−1. It maintained as high as 69 F/g when the current discharge rates upsurged to 15 A g⁻¹, denoting the excellent rate performance. Additionally, a high energy density of 29 Wh g⁻¹ was attained at a maximum power of 4950 W kg⁻¹ with excellent cycling stability of 86 % till 10,000 cycles. These fascinating results pave the way to construct other new electrode materials based on transition metal selenides and CuO for next-generation, long-lasting durability for sustainable supercapacitors.