References System Technique Linear Range (μM) Sensitivity 2 Detection Limit (μM) 0 MWCNT-GCE SWV 4.7 – 5000 0.471 μA/μM-cm2 1.4 0 Chitosan-graphene DPV 20 – 3000 0.247 mA/μM-cm2 0.013 0 MnO2-Graphene DPV 0.05 – 400 2.40 μA/μM- cm2 0.01 0 MWNT-Silica-AuNP-GCE CV 1000 – 5000 8.59 μA/mM - 0 PdNP-GCE Amperometry 20 – 2280 - - 0 Chitosan-graphene CV 50 – 1200 - 50 0 N2-doped graphene DPV 5 – 1300 0.39 μA/μM- cm2 2.2 0 Graphene-doped carbon paste electrode Amperometry 0.17 – 106 0.47 μA/μM- cm2 0.07 0 Graphene-Cu-phthalocyanine-PANi CV 0.5 – 12 24.46 μA/mM 0.063 0 Tryptophan functionalized graphene DPV 200 – 12900 0.0818 μA/mM 10.09 0 Graphene-Nickel hydroxide composite DPV 150 – 300 0.99 μA/μM- cm2 30 0 ERGO-Carbon fiber electrode DPV 8 – 2016.45 0.066 μA/μM 4.5 0 Graphene flowers-Carbon modified fibers DPV 73.52 – 2305.53 - 24.7 0 PdNPs-Graphene-Chitosan-GCE DPV 100 – 4000 20   0 Screen printed graphene electrode DPV 4 – 4500 0.25 μA/mM 0.95 0 Graphene- size selected Pt-GCE DPV 0.15-34.4 0.3457 μA/μM 0.15 0 Fe3O4@ AuNPs-graphene sheet-chitosan-GCE DPV 4-400 7.86 μA/μM 0.3 0 SWCNT-ZnO-GCE CV 200-10000 0.196 μA/μM- cm2 85 [38] Cu-Zeolite A-Graphene-GCE DPV 20-200 - 1.1 [39] Poly(acridine orange) film-RGO-GCE DPV 0.8 – 5000 - 0.3 [40] Graphene ceramic composite CV 3 – 84 6.06 μA/μM cm2 0.82 [41] Double-walled nanotubes-choline-GCE DPV 0.10-777 0.199 μA/μM-cm2 0.03 [42] Chitosan-Graphene-GCE DPV 0.6-1678.1 9.344 μA/μM-cm2 0.1 [43] GO-TemplatedPolyanlineMicrosheets DPV 150-1050 10.88 μA/μM 50 [44] PVP-stabilized graphene electrode CV 10-500 - 1 [45] Graphene doped carbon paste electrode DPV 0.1-106 0.033 μA/μM 0.07 [46] Mesopore-rich active carbon-modified pyrolytic graphite electrode DPV 0.5-2000 2.27 μA/mM 0.3 [47] 3D graphene foams- CuO-GCE CV 0.43-240 2.06 μA/mM-cm2 0.43 [48] AgNPs-RGO-GCE CV 10-1000 1.64 μA/μM -cm2 10 [49] ERGO-GCE DPV 300-2000 0.171 μA/μM-cm2 0.5 [50] CTAB-GO-MWNT-GCE DPV 5-300 401.64 μA/μM-cm2 1 [51] Solar graphene-GCE CV 400-4000 0.00049 μA/μM-cm2 - [52] CuNPs/PSA-GCE CV 0.30-730 - 0.15 This work ZnO-RGO-GCE DPV Jan-00 0.178 μA/μM-cm2 0.01

Table 2: Graphene-based electrochemical sensing of ascorbic acid (CV: Cyclic Voltammetry; DPV: Differential Pulse Voltammetry; SWV: Square Wave Voltammetry)