Hybridizing amorphous NiO nanoflakes and Mn-doped NiP nanosheet arrays for enhanced overall water electrocatalysis

Rational development and facile fabrication of efficient and low-cost bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) play a vital role in hydrogen and oxygen generation by overall water electrocatalysis. Herein, a series of hierarchical coreshell hybrid nanostructured bifunctional electrocatalysts have been successfully synthesized by electrodepositing amorphous nickel oxide nanoflakes (A-NiO x ) on the surface of crystalline Mn-doped Ni 2 P nanosheet arrays (Mn 5 -Ni 2 P). Benefitting from the synergistic effect generated from the outer amorphous NiO x and inner highly crystalline Mn 5 -Ni 2 P nanosheets, the optimal A-NiO x -20/Mn 5 -Ni 2 P sample exhibits quite low overpotentials for the HER (55 mV) and OER (255 mV) to afford a current density of 10 mA cm 2 in alkaline electrolyte. Moreover, the two-electrode water electrolysis device only requires a small cell voltage of 1.54 V to deliver 10 mA cm 2 and shows no obvious attenuation for 20 hours. Our work will provide a valuable method to design and synthesize efficient electrocatalysts for water splitting and other applications of energy conversion and storage. A novel hierarchical coreshell hybrid nanostructured electrocatalyst (A-NiO x -20/Mn-Ni 2 P) showed high bifunctional activity towards overall water splitting.