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Hydrogen, carrying a high energy density and emitting zero greenhouse gases when in use, is particularly promising as an alternative for traditional fossil fuels. Electrochemical water splitting is an economical technology for producing sustainable and high-purity hydrogen gas. However, the intrinsically sluggish kinetics of the anode oxygen evolution reaction (OER) always decreases the efficiency of hydrogen production; the development of highly active and durable electrocatalysts with improved OER kinetics is thus desirable and crucial. Herein, Fe-based metal–organic framework (MOF)-Ni3S2 heterostructure nanocomposites are synthesized on a nickel foam (NF) substrate. The self-supporting Fe MOF-Ni3S2/NF catalyst shows excellent catalytic activities for OER. In alkaline media (1.0 M KOH), only 243 mV of overpotential is needed to reach the current density of 100 mA·cm–2. Even at the commercially viable high current densities of 500 and 1000 mA·cm–2, ultralow overpotentials of 283 and 309 mV are required, respectively. The catalytic activity of Fe MOF-Ni3S2/NF far exceeds that of the noble metal catalysts (e.g., RuO2) and most non-noble metal OER catalysts reported in the literature. In addition, the Fe MOF-Ni3S2/NF nanocomposite exhibits ultrahigh long-term stability at high current densities, with almost no activity attenuation in the chronopotentiometry test conducted at 100 mA·cm–2 and a negligible attenuation (23 mV) at 500 mA·cm–2 for 20 h. Our findings provide insights into designing and preparing cost-effective, highly active, and durable electrocatalysts for OER at high current densities. [ABSTRACT FROM AUTHOR]

Platinum is a widely used precious metal in many catalytic nanostructures. Engineering the surface electronic structure of Pt-containing bi- or multimetallic nanostructure to enhance both the intrinsic activity and dispersion of Pt has remained a challenge. By constructing Pt-on-Au (Pt^Au) nanostructures using a series of monodisperse Au nanoparticles in the size range of 2-14 nm, we disclose herein a new approach to steadily change both properties of Pt in electrocatalysis with downsizing of the Au nanoparticles. A combined tuning of Pt dispersion and its surface electronic structure is shown as a consequence of the changes in the size and valence-band structure of Au, which leads to significantly enhanced Pt mass-activity on the small Au nanoparticles. Fully dispersed Pt entities on the smallest Au nanoparticles (2 nm) exhibit the highest mass-activity to date towards formic acid electrooxidation, being 2 orders of magnitude (75-300 folds) higher than conventional Pt/C catalyst. Fundamental relationships correlating the Pt intrinsic activity in Pt^Au nanostructures with the experimentally determined surface electronic structures (d-band center energies) of the Pt entities and their underlying Au nanoparticles are established., (© 2012 American Chemical Society)