Steps towards highly-efficient water splitting and oxygen reduction using nanostructured β-Ni(OH).

β-Ni(OH) nanoplatelets are prepared by a hydrothermal procedure and characterized by scanning and transmission electron microscopy, X-ray diffraction analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy. The material is demonstrated to be an efficient electrocatalyst for oxygen reduction, oxygen evolution, and hydrogen evolution reactions in alkaline media. β-Ni(OH) shows an overpotential of 498 mV to reach 10 mA cm towards oxygen evolution, with a Tafel slope of 149 mV dec (decreasing to 99 mV dec at 75 °C), along with superior stability as evidenced by chronoamperometric measurements. Similarly, a low overpotential of -333 mV to reach 10 mA cm (decreasing to only -65 mV at 75 °C) toward hydrogen evolution with a Tafel slope of -230 mV dec is observed. Finally, β-Ni(OH) exhibits a noteworthy performance for the ORR, as evidenced by a low Tafel slope of -78 mV dec and a number of exchanged electrons of 4.01 (indicating direct 4e-oxygen reduction), whereas there are only a few previous reports on modest ORR activity of pure Ni(OH).