The demand of high anodic potential for oxygen evolution reaction (OER) because of its sluggish kinetics limits the overall efficiency and practical applications of electrochemical water splitting process. Though metal oxides are envisioned as the potential contenders in this quest due to their high redox potential, nevertheless their low conductivity and instability are among the formidable challenges that need to be addressed. Here, we demonstrate the synthesis and electrochemical applications of covalently linked ultrasmall Ni/NiO NCs (about ∼2 nm) with the exfoliated thiol-functionalized graphene (G-SH) nanosheets as a highly efficient and durable electrocatalyst for OER. Ni/ NiO@G-SH nanohybrid showed a very sharp onset potential of 1.46 V, Tafel slope of 46 mV/dec, turnover frequency (TOF) of 245 s −1 @1.72 V and a steady-state current response at 10 mA/cm 2 for more than 3 days in 0.1 M KOH solution. We believe that the active redox couple of Ni 2+/3+ in nanoscale Ni/NiO at equilibrium fluctuates periodically for the expected sustained OER process. Moreover, the synergistic effect between NCs-GO-SH nanosheets together with the slightly reducing environment due to the strong electron donor thiol groups facilitate the dynamics of the released O 2 as a final product and thus encourage the recycling potential of such nanohybrid materials at low anodic bias.
Oxygen evolution reaction (OER) is a bottleneck process in the water-splitting module for sustainable and clean energy production. Transition metal-based electrocatalysts can be effective as water-splitting catalytic materials because of their appropriate redox properties and natural abundance, but the slow kinetics because of strong adsorption and consequently slow desorption of intermediates on the active sites of catalysts severely hamper the dynamics of the released molecular oxygen and thus remains a formidable challenge. Herein, we report the development of structurally and surface-modified PA-Gd-Ni(OH) 2 Cl (partially alkylated gadolinium-doped nickel oxychloride) nanoclusters (NCs, size ≤ 3 nm) for enhanced and stable OER catalysis at low overpotential and high turnover frequency. The ameliorated catalytic performance was achieved by controlling the surface coverage of these NCs with hydrophobic ligands and through the incorporation of electronegative atoms to facilitate easy adsorption/desorption of intermediates on the catalyst surface, thus improving the liberation of O 2 . Such a surface and structural modification and uniform distribution at the nanoscale length are indeed worth considering to selectively tune the catalytic potential and further modernize the electrode materials for the challenging OER process.
Polymer brush grafted SiO2NPs provide Nafion nanocomposite membranes with superior proton conductivities at ambient and moderately high temperatures over the entire range of relative humidity.
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