Formation of one-dimensional hierarchical MoO2@C–Ni/CoNi hybrids as highly efficient catalysts and protein adsorbents

Abstract

Intercalation of MoO₂-supported nickel nanoparticles (NPs) with a mesoporous carbon layer has been achieved through thermal reduction of hierarchical nickel molybdate with Ni²⁺–polydopamine complex (PDA–Ni²⁺) coated on its surfaces. High coverage of nickel NPs was achieved from nickel molybdate and a carbonized PDA–Ni²⁺ layer under the protection of a nitrogen atmosphere. Doping of other transition metals such as cobalt ions has been achieved at the stage of nickel molybdate formation, with the added amount of cobalt ions playing a vital role in tailoring the composition and morphology of the cobalt-doped nickel molybdate. Cobalt-doped nickel molybdate was able to produce nickel-based bimetallic NiCo alloy NPs within the final configuration by the same strategy as for MoO₂@C–Ni. The mesoporous 2D nanosheets combined with their constructed 1D hollow structures can expose more ultrafine Ni or NiCo sites while enhancing mass diffusion of small molecules or proteins. As a result, the hollow MoO₂–Ni, NiCo/N-doped carbon microtubes exhibited high activity and robust cycling stability in both protein adsorption and the reduction of 4-nitrophenol.