One step molten salt synthesis of nickel nanoparticles incorporated on graphene sheets as non-precious and an effective electrocatalyst for methanol oxidation

Fabricating electrocatalysts based on metal nanoparticles (NPs)/carbon nanomaterials by a facile and cost-effective method have attracted serious attention in the past several years to expand their appli-cations. This study aimed to prepare an effective electrocatalyst based on nickel nanoparticles decorated graphene sheets (NiNPs@Gr) by molten salt synthesis method and to clarify its advantages compared to the calcination method without molten salt. The microscopic characterization revealed that the calci-nation of nickel/carbon precursors in the molten salt medium resulted in nickel NPs supported on graphene sheets, whereas produce NPs with larger sizes supported on porous carbon without molten salt. X-ray diffraction analysis showed that the catalysts prepared by the molten salt method (NiNPs@Gr-S1 and NiNPs@Gr-S2) resulted in nickel NPs with a mixture of crystalline structures (face-centered cubic and hexagonal close-packed). The electrocatalytic activity of NiNPs@Gr-S1 and NiNPs@Gr-S2 toward methanol oxidation was higher than that of the NiNPs@C catalyst prepared without molten salt. The maximum peak current density of NiNPs@C, NiNPs @Gr-S1, and NiNPs @Gr-S2 are 30, 80, and 81.5 mA/ cm2, respectively. Moreover, electrocatalysts derived from molten salt synthesis demonstrated signifi-cantly increased electrocatalytic stability. These results emphasize the synthesis of graphene nanosheet-supported Ni NPs in a single step without any additional chemicals, which makes such a strategy promising in trust acquisition for investors in large-scale production of NiNPs@Gr. (c) 2023 Elsevier Ltd. All rights reserved.