No abstract

We report here non‐enzymatic electrochemical biosensing of H2O2 using a highly stable, metal‐free, tyramine functionalized graphene (T‐GO) based electrocatalytic system. The surface functionalization of tyramine on graphene was carried out chemically. The obtained sheets were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) as well as X‐ray photoelectron (XP), Raman, FT‐IR and UV‐visible spectroscopy. More significantly, the combined results from morphological and structural studies show the formation of a few layers of graphene with effective large‐scale functionalization by tyramine. As a metal‐free electrocatalyst, the as‐synthesized T‐GO shown good electrocatalytic activity towards reduction of H2O2 with a sensitivity of 0.105 mM/cm2 confirmed by combined results from cyclic voltammetric (CV) and linear sweep voltammetric (LSV), and amperometric (i–t) measurements. The lower onset potential (−0.23 mV vs SCE), lower detection limit, wider concentration range (10 mM to 60 mM) with higher electrochemical current and potential stability demonstrated the potential of our non‐enzymatic and cost‐effective T‐GO based electrocatalytic system towards reduction of hydrogen peroxide.

Cu 2 ZnSnS 4 (CZTS) was synthesized by the sonochemical method using 2-methoxyethanol as the solvent and subsequently decorated onto graphene oxide (GO synthesized by the modified Hummers’ method) using two different approaches such as in situ growth and ex situ synthesis followed by deposition. Preliminary characterizations indicated that the synthesized CZTS belongs to the kesterite structure with a sphere-like morphology. The in situ-synthesized CZTS/GO (I-CZTS/GO) composite is used as an efficient electrocatalyst for hydrogen evolution reaction (HER) which revealed superior electrocatalytic activity with a reduced overpotential (39.3 mV at 2 mA cm –2 ), Tafel slope (70 mV dec –1 ), a larger exchange current density of 908 mA cm –2 , and charge transfer resistance (5 Ω), significantly different from pure CZTS. Besides, the I-CZTS/GO composite exhibits highest HER performance with high current stability of which shows no noticeable degradation after i – t amperometry. The catalytic activity demonstrates that the I-CZTS/GO composite could be a promising electrocatalyst in hydrogen production from their cooperative interactions.

Metal free tyramine functionalized graphene oxide (T-GO) is a promising electrocatalyst for oxygen evolution reaction (OER) in alkaline medium having high activity and stability, resulting from the tyramine active sites.