Carbon-Supported Nickel Nanoparticles on SiO₂ Cores for Protein Adsorption and Nitroaromatics Reduction

Supported nonprecious metal nanoparticles (NPs) have attracted considerable interest for their low cost and excellent properties. However, immobilizing them with good dispersion on supports is still a great challenge. Herein, we report a one-pot Stöber method to prepare a high coverage of nickel (Ni) NPs anchored to a resorcinol–formaldehyde (RF)-derived graphic carbon layer on silica. By simple removal of the Ni NPs and silica cores, highly desired hollow graphitic carbon spheres with distinctive properties can be fabricated. Notably, nickel ions not only boost the polymerization of RF-Ni2+ but also control nickel-induced carbon graphitization when Ni NPs are generated from the nickel ions. Meanwhile, the RF-Ni2+ polymer can be finely covered on various supports, including MnO2 nanowires, graphene oxide, and carbon nanofibers, and can easily result in well-dispersed Ni NPs on these supports. Moreover, resorcinol can be replaced by similar chemicals like 3-aminophenol, melamine, and 2,4-dihydroxybenzoic acid to synthesize various polymers, greatly expanding the versatility of this method. Additionally, by a change of the molar ratio of resorcinol to nickel ion or control of the annealing temperature, the coverage and size of Ni NPs could be finely adjusted. Because of the high coverage of Ni NPs with good dispersion, the resultant SiO2@C-Ni hybrids display excellent performance in both the reduction of 4-nitrophenol and adsorption on histidine-rich proteins.