A novel efficient dual-functional electrocatalyst for overall water splitting based on Ni0.85Se/RGO/CNTs nanocomposite synthesized via different nickel precursors

Synthesizing efficient and affordable electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains a crucial problem on the way to practical applications for producing clean H₂ fuel. Herein, high-efficiency and stable transition metal based electrocatalysts Ni_0.85Se-1, Ni_0.85Se-2 and Ni_0.85Se-3 materials with different morphological characteristics were derived via a one-step hydrothermal route using the Ni(OH)₂ and metal-organic framework (Ni-BDC and Ni-BTC) as precursors, respectively. The results showed that Ni_0.85Se-2 exhibited excellent electrocatalytic activity. Subsequently, introducing carbon nanomaterials (RGO and CNTs) to form Ni_0.85Se/RGO/CNTs nanocomposite material further improves the catalytic activity owing to high conductivity. The resulting Ni_0.85Se/RGO/CNTs nanocomposites electrocatalyst showed a low overpotential of 232 mV and 165 mV and a low Tafel slope of 64 mV dec^?1 and 98 mV dec^?1 when the current density was 10 mA cm^?2 for OER and HER, respectively. In addition, the Ni_0.85Se/RGO/CNTs nanocomposites were used as an anode and cathode of the water electrolysis device and the overall water splitting performance was investigated. The results show just a voltage of 1.59 V was required when the current density was 10 mA cm^?2 and good overall water splitting stability for 20 h. The outstanding electrocatalytic performance of Ni_0.85Se/RGO/CNTs is mostly due to its noticeable porous structure, the high conductivity and the large surface area that came from RGO and CNTs.