## 3 Results  
AFM was utilized to identify the successful binding of F-rich peptide onto the GO surface firstly. Figure 2a shows the typical AFM height image of peptides by dropping 10 \(\upmu\)L peptide solution (20 \(\upmu\)g/mL) onto the freshly cleaved mica surface. The adsorbed peptide molecules on the mica surface reveal dispersed sphere-like structure and the corresponding section analysis indicates that the height of peptide molecules is about 1.8 \(\pm\) 0.2 nm. Figure 2b gives an AFM height image of GO nanosheets that deposited onto the mica surface, and the section analysis reveals that GO is in a monolayer with a uniform height of 1.2 \(\pm\) 0.1 nm, which is in accordance with the previous report on the shape and size of GO nanosheets [30]. After binding peptides onto the GO surface, the mixed GO-peptide solution was still highly dispersed. The mono-dispersed GO-peptide nanohybrids were further observed with AFM (Figure 2c), and the section analysis shows that the formed GO-peptide has a mean height of 4.6 \(\pm\) 0.3 nm, which is equal to the sum height value of monolayer GO (1.2 \(\pm\) 0.1 nm) and two peptide molecules (1.8 \(\pm\) 0.2 nm). Therefore, we suggest that the F-rich peptide molecules were bound onto both sides of GO due to the excessive amount of peptide and the high binding ability of F-rich peptide with GO. In addition, we found that a network-like peptide structure was formed on the GO surface (inset of Figure 2c), which means that the binding of peptide onto the GO surface changed the conformation of peptide and promoted their inter-molecular interactions. Figure 2: Morphological characterizations of materials: **(a–d)** AFM characterization of **(a)** peptide; **(b)** GO; **(c)** GO–peptide, the inset is the zoomed area of the red box; and **(d)** GO–peptide–AgNPs; **(e)** TEM image of AgNPs formed on the GO surface; **(f)** corresponding statistical analysis of the size of nanoparticles in **(e)**. Besides the biofunctionalization of GO, the bound peptides could also serve as nucleation and growth sites for the bioinspired synthesis of metallic nanoparticles [23]. Figure 2d shows the typical AFM height image of the created GO-peptide-AgNPs nanohybrids. It can be found that a lot of AgNPs were formed on the surface of GO nanosheets. The corresponding section and statistical analysis indicate that the synthesized AgNPs have a mean size of 5.4 \(\pm\) 1.1 nm. TEM measurement was further utilized to observe the size of AgNPs that formed on the GO surface (Figure 2e), and the statistical analysis shows that the formed AgNPs have a mean size of 4.8 \(\pm\) 1.4 nm (Figure 2f), which is in good agreement with the above AFM data. It is very important to know the amount of peptide and AgNP loading on the GO surface in order to understand the interactions between the peptide and GO. We suggest that ultraviolet-visible spectrophotometry (UV-vis) may be a potential technique to measure the peptide loading on the GO surface by centrifuging the samples after peptide binding. In addition, it is also possible to know the loading of AgNPs onto the GO surface by simply measuring the mass of samples before and after adding Ag\({}^{+}\) and subsequent chemical reduction. All the data could be of benefit for the understanding of the adsorption kinetics of peptide onto the graphene surface. XPS measurement was further utilized to prove the formation of GO-peptide-AgNPs nanohybrids. Figure 3 shows the XPS peaks of C1s, Ag3d, and N1s of the peptide-bioinspired GO-peptide-AgNPs nanohybrids. The strong C1s peak at 283.7 eV comes from the C contents of both GO and peptide molecules, and the appearance of the N1s peak at 398.8 eV is ascribed to the amino acid residue of peptide molecules [30]. In addition, two sharp peaks at 367.0 and 372.9 eV were found, which are assigned to the Ag3d\({}_{5/2}\) and Ag3d\({}_{3/2}\) peaks of AgNPs, respectively [31]. In the current study, the potential application of GO-peptide-AgNPs nanohybrids for the fabrication of electrochemical H\({}_{2}\)O\({}_{2}\) sensor was explored.