Nitrite sensing behaviors of tailored bimetallic oxide CuMnO2 nanostructures

Bimetallic oxide CuMnO2 with multiple lattice sites has many novel properties due to its special delafossite structure. In this work, CuMnO2 nanostructures were prepared via a facile hydrothermal method at 90 °C for 4 h. The prepared CuMnO2 nanostructures were fully characterized, confirming their delafossite structures with a nanoparticle size of about 10–30 nm and a band gap of 1.55 eV. The as-prepared CuMnO2 nanostructures were firstly applied on NaNO2 sensing by differential normal pulse voltammetry (DNPV) and electrochemical impedance spectra (EIS). Because CuMnO2 has smaller particle sizes and band gap, more catalytic centers were exposed and higher catalytic activity was expected. CuMnO2 showed a favorable and efficient electrocatalytic effect with a detection limit of 0.28 μM. The pH variation indicated that the oxidation of NaNO2 on CuMnO2 modified electrodes prefers a weak alkaline environment. Due to its rigid crystal structure, CuMnO2 exhibited long-term stability with the oxidation peak current retention is 96.1% over 20 days.