Herein, an interconnected α-Co(OH)2 structure with a network-like architecture was used as a bifunctional electrocatalyst for the overall water splitting reaction in alkaline medium. The complexing ability of glycine with a transition metal was exploited to form [Co(gly)3 ]- dispersion at pH 10, which was used for the electrodeposition. High-resolution TEM, UV/Vis-diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy were used to confirm that the as-synthesized materials had an α-Co(OH)2 phase. The electrocatalytic oxygen and hydrogen evolution activity of the glycine-coordinated α-Co(OH)2 was found to be approximately 320 and 145 mV, respectively, at 10 mA cm-2 . The material required approximately 1.60 V (vs. reversible hydrogen electrode; RHE) to achieve the benchmark of 10 mA cm-2 for overall water splitting with a mass activity of approximately 63.7 A g-1 at 1.60 V (vs. RHE). The chronoamperometric response was measured to evidence the stability of the material for overall water splitting for up to 24 h. Characterization of the catalyst after the oxygen and hydrogen evolution reactions was performed by XPS and showed the presence of a CoII /CoIII oxidation state.
Keywords: cobalt; electrochemistry; heterogeneous catalysis; hydrogen; water splitting.
© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.