Understanding the underlying physical chemistry governing the nanomaterial-based electrical gas sensing process is pivotal for the rational design of high-performance gas sensors. Herein, using a remarkable ppb-level NO2-gated field-effect nanosensor that is based on a reduced graphene oxide rGO/TiO2 nanoparticle heterojunction, as an exploratory platform, we have established a generic physical chemistry model to quantitatively gain insight into the correlation between the measured source-drain (S-D) current and the gas sorption thermodynamics in this NO 2 nanosensor. Based on thin-film field-effect transistor theory, the measured S-D current leads to the solution to the gas-induced gate voltage, which further solves the surface charge density using the Graham surface potential vs surface charge density function. Consequently, based on the Van't Hoff equation, key thermodynamic information can be obtained from this model including adsorption equilibrium constants and adsorption enthalpy of NO 2 on TiO2 nanoparticles. The acquisition of gas adsorption enthalpy provides a generic and nonspecific method to identify the nature of the adsorbed molecules.
Chinese Acad Sci, Xinjiang Tech Inst Phys & Chem, Lab Environm Sci & Technol, Urumqi 830011, Peoples R China;Chinese Acad Sci, Key Lab Funct Mat & Devices Special Environm, Urumqi 830011, Peoples R China;Univ Chinese Acad Sci, Beijing 100049, Peoples R China;No Illinois Univ, Dept Chem & Biochem, De Kalb, IL 60115 USA
Zu, Baiyi,Lu, Bin,Yang, Zheng,et al. Gas adsorption thermodynamics deduced from the electrical responses in gas-gated field-effect nanosensors[J]. Journal of Physical Chemistry C,2014,118(26):14703-14710.