POROSITY OF CARBON-FILMS APPLIED TO CHEMICAL SENSOR CONSTRUCTION

Investigations on the basic properties of carbons applicable to the co nstruction of semiconducting gas sensors are presented. Development of pore structure of such carbons is considered as the function of carbo nisation temperature and chemical modification of the carbons. The che mical modification consisted in the premixing of furfuryl alcohol with an aqueous solution of sodium acetate. The carbons tested were prepar ed by simulating the ''spry pyrolysis'' technique. The Na-modification resulted in an increase of the W-o value (the Dubinin-Radushkevich ad sorption model) of the carbon films upon increasing the carbonisation temperature while the average pore diameter L was constant. The pore s tructure in the case of Na-modified carbons was the result of Na2CO3 m icrocrystallite formation (from CH3COONa) inside the carbon skeleton a nd their subsequent reaction with the carbon matrix. (C) 1998 Elsevier Science B.V.