Controlled synthesis of NiCo nanoalloys embedded in ordered porous carbon by a novel soft-template strategy

A novel synthesis pathway is proposed in this work to prepare NiCo nanoalloy embedded in highly ordered porous carbons via a soft-template approach. This involves the multicomponent co-assembly of environmental friendly carbon precursors (phloroglucinol and glyoxal), amphiphilic copolymer Pluronic F127 as structure directing agent followed by metal precursor salts incorporation. This synthesis affords a good control of the alloy quantity, composition and particle size in the carbon matrix. The influence of the metal loading in the NiCo alloy and of two chelating agents, i.e., citric acid and oxalic acid on the physical-chemical characteristics of carbon@NiCo materials was investigated. In the absence of chelating agents, the carbon@NiCo hybrid materials have a 2-D hexagonally arranged pore structure, high surface area and porous volume. The NiCo nanoparticles are homogeneously distributed in the carbon network and they exhibit sizes between 30 and 40 nm depending on the Ni/Co ratio. The use of chelating agents allows downsizing the particle size to 15 nm and the modification of the hexagonally carbon structure into a worm-like one. The advantage of the present synthesized hybrids lays in the use of less expensive 3d transition metals than noble elements that may provide comparable effect on hydrogen sorption properties.