Hierarchical Ni/NiTiO3 derived from NiTi LDHs: a bifunctional electrocatalyst for overall water splitting

Developing economical and stable bifunctional electrocatalysts for overall water splitting is of enormous importance for sustainable energy systems. Here, Ni/NiTiO3 with a villiform structure assembled by nanosheets is presented as an efficient bifunctional electrocatalyst. The Ni/NiTiO3 with a molar ratio of 15 : 1 (Ni : Ti) manifests remarkable catalytic performance for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) in alkaline solutions, with onset overpotentials of 270 mV for the OER and similar to 50 mV for the HER. Large amounts of Ni nanoparticles inset in the NiTiO3 nanosheets possess a high specific surface of 28.4 m(2) g(-1) which is far greater than that of bare Ni (7.7 m(2) g(-1)). The results of long-term OER operation confirm that the introduction of Ti4+ is favorable for enhanced stability. When the catalyst is employed as both the cathode and anode for overall water splitting, it displays an onset potential of 1.55 V in 1 M KOH solution which can rival that of the integrated performance of Pt/C and RuO2. Hence, our Ni/NiTiO3 electrocatalysts have enormous potential for realistic large-scale water splitting.