Drastic modification of graphene oxide properties by incorporation of nickel: a simple inorganic chemistry approach

Abstract

Strong increase in electrical conductivity of graphene oxide (GO) (I ≈ 10−9 A) is found by addition of Ni nanoparticles (NiNPs) preliminarily solved by HCl (Nisol) (I ≈ 10−4 A) or powder (Nipow) obtained from this solution (I ≈ 10−6 A), while simply mixing GO with NiNPs an insulator similar to pure GO is obtained. Thus, Nisol and Nipow can be used to transform GO from insulator to semiconductor. One of the transformation mechanisms is Ni as spillover. At the same time, different kinds of the magnetic response are obtained on GO and reduced GO (rGO) samples with and without Ni. Weak paramagnetic response is detected in pure GO. Stronger paramagnetic behavior is observed for GO and rGO mixed with Nisol or Nipow. Pure rGO sample shows weak ferromagnetism represented by slim but visible hysteresis with remnant magnetization M r of 0.05 emu/g. GO with NiNPs presents clear hysteresis with M r of 2.8 emu/g, while sample prepared by addition of NiNPs to rGO presents the largest hysteresis with M r as high as 11.8 emu/g. Thus, the optimal procedure to obtain the magnetic response requested for particular application can be chosen.