Novel coal-based carbon/K2CO3 prepared by improved alkali activation for highly sensitive detection of formaldehyde

Conventional coal-based carbon activation usually requires strong acid washing operation after activation, which not only consumes more experimental time but also pollutes the environment. In this study, a novel method for the preparation of coal-based carbon gas-sensitive materials is described and its gas-sensitive properties are investigated. Specifically, a novel composite coal-based carbon/K 2 CO 3 gas-sensitive material was prepared more easily by using low-cost coal as the carbon source and KOH as the activator without acid washing after activation, which was unexpectedly found to possess excellent gas-sensitive properties, which gave us great encouragement. The samples obtained at the activation temperature of 500 °C and with a carbon-to-alkali ratio of 1:1 have more defective active sites as well as chemisorbed oxygen content, which is advantageous for enhancing the gas-sensitive performance of the samples. In addition, the introduced alkaline potassium carbonate component also favors the adsorption of acidic formaldehyde gas. The response of the sensor fabricated using the above sample was 6415.68 % for 500 ppm formaldehyde at room temperature and a response cycle was completed in about ten seconds. In addition, the fabricated gas sensor was applied to the monitoring of volatile formaldehyde in paints, which shows that the sensor has the potential to be applied in the detection of formaldehyde gas emitted in the field of home decoration and building materials.