Fig. 1: Morphological characterizations of Ni-Co-P/NF and reference samples.

SEM images of a Ni-Co-Pre/NF and b Ni-Co-P/NF with a magnified image in the inset; c TEM image of Ni-Co-P/NF, in which the squared Area 1 and Area 2 are magnified and shown respectively in (d) and (e) with a FFT pattern of the Area 1 in the inset of (d); f HRTEM image of the Ni-Co-P/NF with a further magnified image in the inset; g STEM-EDS elemental mapping of Ni-Co-P/NF.