Small-sized carbon nanospheres via hydrothermal carbonization of ascorbic acid: An efficient supporting material for enhancing Cu nanocrystals electrochemical sensor performance

This work developed low-temperature and environmentally friendly hydrothermal carbonization approach for synthesizing small-sized carbon nanospheres [C(s) Ns]. It is demonstrated that C(s) Ns act as an efficient supporting material, thereby enhancing the sensor performance of Cu nanocrystals. Compared to pure Cu, the C@Cu Ns show enhanced sensor performance toward glucose, sodium nitrite, and formaldehyde. A comprehensive analysis was carried out to investigate the mechanism of enhanced sensor performances. Furthermore, the effects of Cu loading rates and the sizes of C Ns on sensor performance were systematically examined. In alkaline solutions, the sensitivity of C(s)@Cu-8% [ C(s) Ns with Cu 8 at% loading rate] in detecting glucose and formaldehyde was 1.94-fold and 3.06-fold higher than that of Cu nanocrystals, respectively. In neutral solutions, the sensitivity of C(s)@Cu-8% for detecting NaNO2 was 3.49-fold higher than that of Cu nanocrystals. As applied in actual substances, the obtained C(s)@Cu Ns could achieve the detection of NaNO2 in aqueous solutions and sugar content in Nescafé. This work introduced an economical sensor that features multifunctionality and enhanced performance, the utilization efficiency for Cu nanocrystals was enhanced while maintaining cost-effectiveness. Both the requirements for high-concentration glucose and nitrite detection were addressed.