Ni12P5 nanoparticles decorated on carbon nanotubes with enhanced electrocatalytic and lithium storage properties

Abstract

Transition-metal phosphides (TMPs) have been proved to be of great importance in electrochemical energy conversion and Li-ion storage. In this work, we have designed a useful one-pot hot-solution colloidal synthetic route for synthesizing a new kind of unique hybrid nanostructures (the Ni₁₂P₅/CNT nanohybrids) by direct in situ growth of Ni₁₂P₅ nanocrystals onto oxidized multiwall carbon nanotubes (CNTs). The CNTs can improve the conductivity of the hybrids and effectively prevent the aggregation of Ni₁₂P₅ nanoparticles in the cycle process. When they are evaluated as a novel non-noble-metal hydrogen evolution reaction (HER) catalyst operating in acidic electrolytes, the Ni₁₂P₅/CNT nanohybrids exhibit an onset overpotential as low as 52 mV and a Tafel slope of 56 mV dec⁻¹ and only require overpotentials of 65 and 129 mV to attain current densities of 2 and 10 mA cm⁻², respectively. Moreover, they also exhibit enhanced electrochemical performance for lithium-ion batteries serving as an anode material; the Ni₁₂P₅/CNT nanohybrids show a high capacity, excellent cycling stability and good rate performance. Their unusual properties arise from a synergetic effect between Ni₁₂P₅ and CNTs.