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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.

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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.

Direct ethanol fuel cells (DEFCs) are one of the resourceful and sustainable technologies for energy applications. Ethanol oxidation has been used to construct cost-effective and proficient electrocatalysts to substitute noble-based electrocatalysts like Rh, Pd, Ir, and Ag. Here in, we have presented a surface modification approach of doping a crucial oxophilic character metal onto a transition metal with carbon support. Noble metal-free cobalt−bismuth bimetallic nanoparticledecorated reduced graphene oxide (Co−Bi@rGO) electrocatalysts were fabricated for enhanced ethanol oxidation reaction from their synergetic effect of rGO, Co, and Bi. A highly active, cost-effective, and efficient approach has been developed for the preparation of Co−Bi@rGO (Co NPs; ∼2 nm), initially Bi@rGO (Bi NPs@rGO; ∼50 nm), by a simple reduction method followed by Co, by Galvanic exchange of Bi atoms with Co. The as-synthesized nanocomposites were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and BET surface area measurement studies. Cyclic voltammetric studies show an ultralow onset potential of 0.28 V with a high current density of 10.25 mA/cm 2 , having a higher enhancement factor for Co−Bi@rGO compared to other individuals, including Bi NPs, Bi@rGO, and rGO under similar electrolyte conditions, which could be due to their synergetic cooperative interactions at electrified interfaces. Combined results from chronoamperometry (i−t) and electrochemical impedance spectroscopy show that Co−Bi@rGO is highly durable and sensitive toward the ethanol oxidation reaction compared to individual counterparts. This work also provides the noble metal-free bimetallic electrocatalysts for ethanol oxidation and assists in hydrogen production from an agricultural base.

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Direct urea fuel cells (DUFCs) are proficient technology for sustainable energy applications as well as for urea waste present in water. Basically, urea oxidation suffers from sluggish electrokinetics and the proposed complex formation eventually needs six electron transfers due to their large scale utilization. The electrochemical oxidation of urea on Ni nanoparticles (Ni NPs) is perceived as energetic, but it has lower stability due to catalyst deactivation and limited active sites and is found to be responsible for inferior activity towards oxidative conversion of urea. Herein, we have demonstrated the synthesis of Ni−Bi bimetallic nanoparticles by using the chemical reduction method, structurally characterized by X-ray diffraction (XRD), having mixed phases of FCC and a rhombohedral structure, corresponding to Ni and Bi, respectively. BET surface area measurement concluded that the surface area of Ni−Bi bimetallic nanoparticles is higher than that of individual Ni and Bi NPs. TGA exhibited that the Ni−Bi bimetallic composite is thermally more stable compared to individual Bi and Ni NPs. Morphological studies from transmission electron microscopy (TEM) confirm heterostructured interface formation of Ni (5 nm) with Bi (3 nm) nanoparticles. Furthermore, electrochemical activity of Ni−Bi bimetallic NPs was investigated by cyclic voltammetric studies, showing a high current density of catalyst of 37.5 mA/cm 2 with an ultralow potential of E = 0.29 V vs SCE compared to individual Ni and Bi NPs, which may be due to their synergetic structural and electronic effects at the nanoscale. The EIS reveals that the Ni−Bi bimetallic NPs have faster electron transfer, which could be due to having merits like stabilization of the intermediate, synergetic effect, and comparatively more adsorption of urea molecules. This work provides the noble metal-free electrocatalyst for the mechanistic path for urea oxidation and assists in significant implication toward H 2 production from natural and manmade wastes like animal/human urine, urea-rich industrial effluent water, and other industrial and medical wastes.

Herein, cobalt oxide (Co3O4) decorated reduced graphene oxide (rGO) based nanoelectrodes fabricated by chemical reduction method using hydrazine hydrate, also it shows enhanced electrocatalytic activity for oxygen evolution (water oxidation)...