Effect of UV irradiation on magnetic behavior of reduced graphene oxide decorated with nickel nanostructure

Reduced graphene oxide (RGO) decorated with nickel has been synthesized via an in-situ reduction of graphene oxide (GO) and nickel nitrate using NaOH and hydrazine. The starting materials Ni (NO3)(2) and GO were taken in two different ratios and the products formed were designated as RGNi(2) and RGNi(1). The formation of the composite was confirmed by the appearance of X-ray diffraction peaks at 44.5 degrees, 51.9 degrees, 76.5 degrees corresponding to Ni and at 24.8 degrees and 43.2 degrees for RGO. The RGNi(2) was irradiated with UT light (lambda=254 nm) for different durations (2, 6, 12, 24 and 48 h). Intensity ratio of d and g-bands (I-d/I-g) of Raman spectra increases from 1.18 to 1.47 over the duration of irradiation period (2-48 h). The magnetization measurements using the vibrating sample magnetometer (VSM) of these samples reveal their ferromagnetic behavior. The calculated saturation magnetization (M-s) value of Ni, RGNi(1)and RGNi(2) is 47.86, 30.56 and 8.25 emu/g respectively and the corresponding coercivity (Hc) value is found to be 181, 227 and 296 Oe. The Ms of RGNi(2) is found to increase to 10.65 emu/g after 48 h of irradiation. This enhancement in the Ms( similar to 23%) with irradiation may be due to defect formation by the UV light.