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

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. Ni2P, NiS2 and NiSe2 were prepared by solid-phase reaction, and the 3D nanoflower increased the open structure and greatly enhanced catalytic activity. The Ni2P/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: Ni2P > NiS2 > NiSe2 > Ni(OH)2. The Ni2P/Ti and Ni(OH)2/Ti electrodes were assembled into an integrated water splitting electrolytic cell. The water electrolysis device assembled with the Ni2P/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.