Defective nickel zirconium oxide mesoporous bifunctional electrocatalyst for oxygen evolution reaction and overall water splitting

• A single phase zirconium nickel oxide has been synthesized by simple sol-gel method. • Zr 0.012 Ni 4.3 O 0.68 has activity only 294 mV overpotential at 10 mA cm −2 . • The conductivity and oxygen vacancies increase as a function of Ni concentrations. • The synthesized material is also efficient toward overall water splitting. Designing a robust electrocatalyst for Oxygen evolution reaction (OER) and other energy transformation devices is still challenging. To meet this trial, numerous oxides and bimetallic oxides consisting of oxygen vacancies spring up a critical parameter for outstanding OER electrocatalyst. In this work, for the first time, single-phase zirconium nickel oxide (ZrNi 4 O) nanospheres with different concentrations of Ni are fabricated by a facile sol-gel method. Among all the synthesized series of ZrNi 4 O, Zr 0.012 Ni 4.3 O 0.68 deposited on glassy carbon (GC) electrode exhibits remarkable OER performance requiring only 294 mV overpotential at 10 mA cm −2 . Such unusual performance is owing to the availability of a huge number of various oxygen vacancies created in the non-stoichiometric compound Zr 0.012 Ni 4.3 O 0.68 . In addition to this, the effect of substrate and medium on Zr 0.012 Ni 4.3 O 0.68 is also investigated. The Zr 0.012 Ni 4.3 O 0.68 is also analyzed as overall electrocatalyst for electrolysis in two electrode system requiring only 1.55 V cell voltage for 20mAcm −2 current density. As the concentration of Ni varies in Zr x Ni 4-x O σ , the amount of oxygen vacancies increases in cubic system of ZrNi 4 O, consequently enhancing the conductivity of the electrode. That ultimately augments the intrinsic activity (specific activity) and empirical usage (Mass activity) of electrocatalysts toward OER.