Nitrophenol sensors have garnered interest in pharmaceuticals, agriculture, environment safety and explosives. Various methods have been proposed to detect 4-nitrophenol, but nitrophenol isomers such as 2,4-dinitrophenol (DNP) and 2,4,6-trinitrophenol have been comparatively less studied. For the first time, the present work explores graphitic nanocarbon, i.e., carbon black (CB) interface for sensing of DNP. Two reduction potentials were noted at − 0.48 and − 0.64 V for o-NO2 and p-NO2 moieties, respectively, at CB/GCE. At the same time, bare GCE (glassy carbon electrode) shows a single reduction potential at − 0.7 V. The electrocatalytic effect and adsorption ability of the interface was studied from the DNP concentration effect. Scan rate and pH studies suggest that the CB acquires four electrons for NO2 reduction by the diffusion phenomenon. A broad detection range of 10–250 μM DNP with a very low detection limit of 0.13 (o-form) and 0.15 μM (p-form) was achieved using the CB interface. The real-time applicability of the fabricated sensor was evaluated using commercially available beverages with excellent recovery values. The stability, repeatability and reproducibility of the CB interface were successfully confirmed. Comparison of the sensing parameters of the developed sensor with those reported in literature reveals excellent detection limit and response time for the CB-interfaced DNP sensor, indicating its potential for environmental and commercial applications.

Most recently, graphene-related composite-modified electrode surfaces are been widely employed to improve surface interactions and electron transfer kinetics. Hydrothermally prepared strontium pyro niobate (SPN) and reduced graphene oxide/ strontium pyro niobate (RGOSPN) nanostructures reveal excellent morphology. X-ray diffraction analysis of SPN and RGOSPN agree with standard data. Thermogravimetry–differential scanning calorimetry analyses show that RGOSPN has higher thermal stability than SPN. In addition, from the polarization–electric field (P–E) loop measurements, the estimated value of remnant polarization (Pr) and coercive electric field (Ec) of SPN are 0.039 μC cm−2 and − 2.90 kV cm−1 and that of RGOSPN nanocomposite are 0.0139 μC cm−2 and − 2.04 kV cm−1. Cyclic voltammetry measurements show that RGOSPN nanocomposite manifests the possibility of electrochemical reversibility beyond long cycles without change in performance. The redox cycle reveal that RGOSPN can be used as part of a composite electrode for hybrid capacitors dynamic conditions. Moreover, the specific capacitance of SPN and RGOSPN was calculated using galvanostatic charge–discharge (GCD) technique. The observed energy density of 9.1 W h kg−1 in RGOSPN is higher when compared with previous reported values.