Heat Treatment of Graphene Oxide/Thiourea Mixture in the Solid State and Application for Detection of Uric acid and pH Sensing

The heat treatment of the graphene oxide/ thiourea mixture was done by the tube furnace equipped with  an  argon  inlet.  The  graphene  oxide/  thiourea  sample  was  characterized  by  UV–visible spectrometry,  Thermogravimetric  analysis,  Fourier  transform  infrared  spectroscopy  and  X-ray photoelectron  spectroscopy.  The  UV–vis  absorption  spectra of graphene  oxide  was  shown the characteristic  absorbance  of  graphene  oxide,  and  the  Fourier  transform  infrared  spectra  showed carboxylic  acid  group  and  thiocyanate  on  the  surface  of  graphene  oxide/thiourea.  The deconvolution  of  X-ray  photoelectron  spectra  showed  the  sulfur  and  nitrogen  on  the  surface  of graphene  oxide.  The  peak  area,  the  percent  of  carbon,  oxygen,  nitrogen,  and  sulfur  of  modified graphene  oxide  based  on  Scofield’s  relative  sensitivity  factor  (RSF),  was  73,  16,  7,  and  4, respectively.  The  fluorescence  measurements  of the  modified  graphene  oxide  suspension  in  the different  pH  were  investigated.  The  alkaline  solution  showed  the  most  emission  intensity.  The sample  was  shown  good  interaction  with  uric  acid  in  the  alkaline  solution  compared  to  other substances, including thiamin, nicotinamide, urea, ascorbic acid, glucose, and lauric acid, based on fluorescence spectroscopy.