File Name : fig. s1.tif

Caption : fig. s1 (a) xrd pattern of ni-p/cc, (b) sem image of ni-p/cc and (c) eds spectrum of
ni-p/cc with the deposition time of 120 s at the current density of 1 ma cm-2.

File Name : fig. s2.tif

Caption : fig. s2 eds spectrum of (a) ni2p/cc, (b) ni-p/ni2p/cc-1, (c) ni-p/ni2p/cc-2 and (d)
ni-p/ni2p/cc-3.

File Name : fig. s3.tif

Caption : fig. s3 calculated exchange current density for ni2p/cc, ni-p/ni2p/cc-1, ni-p/ni2p/cc-2,
ni-p/ni2p/cc-3, and pt/c/cc in 1.0 m koh solution by applying extrapolation of tafel plot data.

File Name : fig. s4.tif

Caption : fig. s4 cv curves of (a) ni2p/cc, (b) ni-p/ni2p/cc-1, (c) ni-p/ni2p/cc-2 and (d)
ni-p/ni2p/cc-3 in 1.0 m koh solution at different scan rates.

File Name : fig. s5.tif

Caption : fig. s5 cv curves of ni2p/cc, ni-p/ni2p/cc-1, ni-p/ni2p/cc-2 and ni-p/ni2p/cc-3 in 1 m
pbs (ph = 7) with a scan rate of 50 mv s-1.

File Name : fig. s6.tif

Caption : fig. s6 nyquist plots of ni-p/ni2p/cc-2 composite at different overpotential values.

File Name : fig. s7.tif

Caption : fig. s7 time-dependent current density curve of ni2p/cc and ni-p/ni2p/cc-2 at a constant overpotential for 20 h in 1.0 m koh solution.

File Name : fig. s8.tif

Caption : fig. s8 (a) xrd pattern, (b) sem image and (c-f) xps spectra of ni-p/ni2p/cc-2 after long-term stability test in 1.0 m koh solution.