Favoring the Selective H2O2 Generation of a Self-Antibiofouling Dissolved Oxygen Sensor for Real-Time Online Monitoring via Surface-Engineered N-Doped Reduced Graphene Oxide.

Dissolved oxygen (DO) is a key parameter in assessing water quality, particularly in aquatic ecosystems. The oxygen reduction reaction (ORR) has notable prevalence in energy conversion and biological processes, including biosensing. Nevertheless, the long-term usage of the submersible DO sensors leads to undesirable biofilm formation on the electrode surface, deteriorating their sensitivity and stability. Recently, the reactive oxygen species (ROS), such as the two-electron pathway ORR byproduct, H2O2, had been known for its biofilm-degradation activity. Herein, for the first time, we reported N-doped reduced graphene oxide (N-rGO) for H2O2 selectivity as the self-antibiofouling DO sensor. Introducing foreign atom doping could reorient the electron network of graphene by the electronegativity gap, which facilitated highly selective and efficient two electron pathway of ORR. Mitigating the N content of N-rGO had enhanced the H2O2 selectivity (57.5%) and electron transfer number (n = 2.84) in neutral medium. Moreover, the N-rGO could be integrated to a wireless DO monitoring device that might realize an applicable device in the aquatic fish farming.

Graphene quantum dots induced defect-rich NiFe Prussian blue analogue as an efficient electrocatalyst for oxygen evolution reaction.

High energy resource demand has led to the rapid development of hydrogen as a clean fuel through electrolytic water splitting. The exploration of high-performance and cost-effective electrocatalysts for water splitting is a challenging task to obtain renewable and clean energy. However, the sluggish kinetics of oxygen evolution reaction (OER) greatly hindered its application. Herein, a novel oxygen plasma-treated graphene quantum dots embedded Ni-Fe Prussian blue analogue (O-GQD-NiFe PBA) is proposed as a highly active electrocatalysts for OER. Furthermore, the defect induced by GQD can provide an abundant lattice mismatch in the matrix of NiFe PBA, which further facilitates faster electron transport and kinetic performance. After optimization, the as-assembled O-GQD-NiFe PBA exhibits excellent electrocatalytic performance towards OER with a low overpotential of 259 mV for reaching a current density of 10 mA cm-2 and impressive long-term stability for 100 h in an alkaline solution. This work broadens the scope of metal-organic frameworks (MOF) and high-functioning carbon composite as an active material for energy conversion systems.