02259nas a2200229   4500008004100000022001400041245013200055210006900187260007500256300002400331490000600355520136500361100002101726700002401747700002001771700002201791700001801813700001301831700002401844700003001868856013101898       2016                        eng d  a1614-683200aLow-overpotential electrocatalytic water splitting with noble-metal-free nanoparticles supported in a sp(3) n-rich flexible COF0 aLowoverpotential electrocatalytic water splitting with noblemeta  aPOSTFACH 101161, 69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJUL  aArticle No. 16001100 v63 a<p>Covalent organic frameworks (COFs) are crystalline organic polymers with tunable structures. Here, a COF is prepared using building units with highly flexible tetrahedral sp(3) nitrogens. This flexibility gives rise to structural changes which generate mesopores capable of confining very small (&lt;2 nm sized) non-noble-metal-based nanoparticles (NPs). This nanocomposite shows exceptional activity toward the oxygen-evolution reaction from alkaline water with an overpotential of 258 mV at a current density of 10 mA cm(-2). The overpotential observed in the COF-nanoparticle system is the best in class, and is close to the current record of approximate to 200 mV for any noble-metalfree electrocatalytic water splitting system-the Fe-Co-Ni metal-oxide-film system. Also, it possesses outstanding kinetics (Tafel slope of 38.9 mV dec(-1)) for the reaction. The COF is able to stabilize such small-sized NP in the absence of any capping agent because of the COF-Ni(OH)(2) interactions arising from the N-rich backbone of the COF. Density-functional-theory modeling of the interaction between the hexagonal Ni(OH)(2) nanosheets and the COF shows that in the most favorable configuration the Ni(OH)(2) nanosheets are sandwiched between the sp(3) nitrogens of the adjacent COF layers and this can be crucial to maximizing their synergistic interactions.</p>1 aMullangi, Dinesh1 aDhavale, Vishal, M.1 aShalini, Sorout1 aNandi, Shyamapada1 aCollins, Sean1 aWoo, Tom1 aKurungot, Sreekumar1 aVaidhyanathan, Ramanathan  uhttps://library.ncl.res.in/content/low-overpotential-electrocatalytic-water-splitting-noble-metal-free-nanoparticles-supported