Controlled synthesis of self-supportive hydrangea shaped Ni based hydroxide/phosphide for efficient overall water splitting and full pH hydrogen evolution.

• Ni(OH) 2 nanoflowers were prepared on Ti mesh using rapid electrodeposition. • Ni(OH) 2 /Ti exhibited excellent OER catalytic activity (η 100 = 290 mV). • Flowerlike Ni 2 P/Ti showed outstanding HER performance over the full pH range. • DFT calculation confirm that Ni and P as active sites have the best |Δ G H* |. • The Ni 2 P/Ti (−) || Ni(OH) 2 /Ti (+) displayed a low voltage of 1.493 V at 10 mA cm−2. The exploration of efficient, robust and nonprecious transition metal electrocatalysts for electrochemical hydrolysis is urgently needed. Herein, we developed Ni(OH) 2 with 3D nanoflower structure on the titanium mesh by a simple electrodeposition method. The Ni(OH) 2 /Ti exhibited excellent oxygen evolution reaction performance and achieved 10 mA cm−2 at 190 mV with fast kinetics in alkaline conditions. Ni 2 P, NiS 2 and NiSe 2 were prepared by solid-phase reaction, and the 3D nanoflower increased the open structure and greatly enhanced catalytic activity. The Ni 2 P/Ti electrode required an overpotential of 52, 88 and 109 mV to reach 10 mA cm−2 for hydrogen evolution reaction in acidic, alkaline and neutral media, respectively. The results of electrochemical measurements and mechanistic studies showed that the catalytic activity of HER: Ni 2 P > NiS 2 > NiSe 2 > Ni(OH) 2. The Ni 2 P/Ti and Ni(OH) 2 /Ti electrodes were assembled into an integrated water splitting electrolytic cell. The water electrolysis device assembled with the Ni 2 P/Ti and Ni(OH) 2 /Ti electrodes only needed a low potential of 1.608 V to achieve 50 mA cm−2 in alkaline environment and was operated stably for 50 h. [ABSTRACT FROM AUTHOR]