Free-standing, flexible β-Ni(OH) ₂ /electrochemically-exfoliated graphene film electrode for efficient oxygen evolution

The oxidation of water into molecular oxygen (oxygen evolution reaction, OER) is a pivotal reaction in many energy conversion devices. The high cost of IrO ₂ , however, seriously hinder its large-scale applications in water oxidation. Here, we have at first reported a free-standing and flexible film electrode consisting of 2D β-Ni(OH) ₂ /electrochemically-exfoliated graphene hybrid nanosheets (NiG-2), which is synthesized by a solvothermal reaction and an assembly process. The as-obtained NiG-2 film electrode exhibited an excellent electrocatalytic OER activity with an extremely low OER onset overpotential of ∼250 mV in a 1 M KOH aqueous solution, which is lower than these of the commercial Ir/C (370 mV at 10 mA cm ⁻² ) catalyst.