Ni–Co–P functionalized Nitrogen-Doped-Carbon quantum dots for efficient methanol electrooxidation and nanofluid applications

Nanocomposite materials that can be utilized for different applications related to energy production and energy transfer are in great demand. Herein, nitrogen-doped carbon quantum dots (N-CDs) are prepared via a facile microwave-assisted method. The as-prepared N-CDs are further functionalized with nickel cobaltite (NiCo2O4/N-CDs), nickel cobalt tungstate (Ni0.5Co0.5WO4/N-CDs) and nickel cobalt phosphide (NiCoP/N-CDs) through a hydrothermal process. These nanocomposites can function as anode electro-catalysts for direct methanol fuel cells, or as nanoparticles for the preparation of nanofluids. NiCoP/N-CDs exhibits the highest performance in both applications. It achieves a peak current density of 74.7 mA cm−2 for methanol electrooxidation in an alkaline medium with current retention of 92 % after 100 charging cycles. The high catalytic activity of NiCoP/N-CDs is attributed to its high crystallinity, large pore size, and nanoflakes-like surface morphology. The high thermal stability and electrical conductivity of the nanocomposite-based nanofluids hold promise for various heat transfer operations.