Synergistic enhancement of triethylamine sensing performances via oxygen vacancy-rich Co-doped MnO2@MnCo2O4.5 nanorods/nanosheets

Abstract

The presence of oxygen vacancies in p-type metal–oxide semiconductors significantly boosts gas-sensing performance. Despite this, the current literature lacks extensive studies on inducing oxygen vacancies in manganese-based oxides to enhance their intrinsic activities. Thus, developing a simple and efficient synthetic method to generate abundant oxygen vacancies in manganese-based oxides is essential. In this study, we achieved a straightforward transformation of Co-doped-MnO₂ into MnCo₂O_4.5 nanosheets with plentiful oxygen vacancies by reducing then with NaBH₄ solution at room temperature. This uncomplicated process effectively produced MnCo₂O_4.5 nanosheets with numerous oxygen vacancies, which markedly improved the gas-sensing properties. The hierarchical Co-doped-MnO₂@MnCo₂O_4.5 nanorods/nanosheets nanocomposite, benefiting from the Co doping and reduction strategy, demonstrated superior gas-sensing performance compared to pristine MnO₂ nanowires. Specifically, the sensor's response based on Co-doped-MnO₂@MnCo₂O_4.5 to 50 ppm TEA gas increased by 340% at an optimal operating temperature of 170 °C, which is 2.7 times higher than that of pristine MnO₂. This exceptional performance is attributed to the synergistic effect of oxygen vacancies and active sites within the hierarchical nanocomposite structure.