## 3 Results
To obtain an optimal applied potential for the sensor test, we measured the CVs of the fabricated GO-peptide-AgNPs/GCE by adding H\({}_{2}\)O\({}_{2}\) with different concentrations (Figure 4). It can be found that a strong reduction peak at about \(-\)0.51 V appeared, which was then selected as the applied potential for the next current-time (I-T) measurement. Figure 3: XPS spectrum of the C1s, Ag3d, and N1s peaks of GO–peptide–AgNPs nanohybrids. Figure 5a displays a typical I-T curve with GO-peptide-AgNPs/GCE on successive additions of H\({}_{2}\)O\({}_{2}\). It is clear that the addition of 20 uM H\({}_{2}\)O\({}_{2}\) into the system caused a rapid current response. The corresponding calibration of the obtained I-T data indicates a regular response towards H\({}_{2}\)O\({}_{2}\) with a linear detection range from 0.02 to 18 mM (Figure 5b). According to the linear fit, a detection limit of 0.13 uM with a sensitivity of 3.6 uA\(\cdot\)mM\({}^{-1}\) was calculated (S/N = 3). To make it more clear, we compared the sensing performance of our H\({}_{2}\)O\({}_{2}\) sensor based on GO-peptide-AgNPs nanohybrids with several reported sensors based on graphene-NPs [23; 32; 33; 34; 35; 36], as shown in Table 1.  
Figure 4: CVs of the fabricated GO–peptide–AgNPs/GCE by adding H\({}_{2}\)O\({}_{2}\) with different concentrations. Figure 5: Performance of the H\({}_{2}\)O\({}_{2}\) sensor based on GO–peptide–AgNPs nanohybrids: (**a**) I–T response; (**b**) calibration curve; (**c**) anti-interference capability; and (**d**) reuse stability. Figure 5c shows the anti-interference test of the fabricated electrochemical sensor by adding three relevant electroactive species, dopamine (DA), ascorbic acid (AA), and uric acid (UA). It can be found that the addition of all species did not cause any current response, which identifies the high selectivity of the fabricated sensor based on GO-peptide-AgNPs nanohybrids towards the detection of H\({}_{2}\)O\({}_{2}\). In addition, the reuse stability of the fabricated H\({}_{2}\)O\({}_{2}\) sensor was investigated (Figure 5d). After using for seven times, the current response towards the same H\({}_{2}\)O\({}_{2}\) concentration still kept more than 95% of the original value. The further long-term stability test indicates that the fabricated H\({}_{2}\)O\({}_{2}\) sensor based on GO-peptide-AgNPs nanohybrids can be stable stored at 4 \({}^{\circ}\)C for at least 13 days (Figure 6). Based on the above results, it can be concluded that this H\({}_{2}\)O\({}_{2}\) sensor based on GO-peptide-AgNPs nanohybrids reveals high performances with low detection limit, strong selectivity, good reuse capability, and long-term stability. We suggest that there are a few advantages to using this kind of sequence-designed peptide for biofunctionalization of GO or reduced GO (RGO) and subsequent bioinspired synthesis of NPs. Firstly, the design of peptide molecules with specific amino acids is helpful for the facile biofunctionalization of GO and RGO. Secondly, the introduction of peptide onto the GO or RGO surface can greatly improve the solubility and biocompatibility of graphene, and extend their biomedical and nanotechnological applications. Thirdly, the bound peptide molecules could serve as nucleation and growth templates for the formation of metallic or metallic oxide nanoparticles for electrochemical sensors and catalysis. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Materials** & **Linear Range** & **Detection Limit** & **Reference** \\ \hline RGO–peptide nanofiber–AgNPs & 0.05–5 mM & 10.4 \(\upmu\)M & [23] \\ RGO–Polymer–AgNPs & 0.1–40 mM & 28 \(\upmu\)M & [32] \\ RGO–AuNPs & 0.5 \(\upmu\)M–0.5 mM & 0.22 \(\upmu\)M & [33] \\ RGO–AgNPs & 0.1–100 mM & 31.3 \(\upmu\)M & [34] \\ Graphene/Au/horseradish peroxidase/chitosan & 0.005–5.13 mM & 1.7 \(\upmu\)M & [35] \\ Hb/AuNPs/ZnO/RGO & 0.006–1.13 mM & 0.8 \(\upmu\)M & [36] \\ GO–peptide–AgNPs & 0.02–18 mM & 0.13 \(\upmu\)M & This work \\ \hline \hline \end{tabular}
\end{table}