The bioprepared graphene sheets were checked for NH4 + sensing via UV-Vis absorption spectroscopy, where graphene suspension was mixed with NH4Cl solution at different concentrations (0.5 -3.75 mM). The change in the absorbance was quantified, and the calibration plot was obtained to estimate LoD and LoQ. Further, to comprehend the sensing mechanism, control and ammonium-treated graphene were examined under Raman and FTIR spectroscopy for changes in the surface chemical state and lattice structure introduced by NH4 + ions.