Gas sensors, methods of preparation thereof, methods of selecting gas sensor materials, and methods of use of gas sensors

A method of detecting a gas based on the acidic or basic characteristic of the gas using a conductometric porous silicon gas sensor, comprising:

• exposing a gas to one or more conductometric porous silicon gas sensors, wherein each of the conductometric porous silicon gas sensors is operative to transduce the presence of a gas into an impedance change, wherein the impedance change correlates to the gas concentration,
• wherein the conductometric porous silicon gas sensor has a porous silicon layer, wherein one or more of the conductometric porous silicon gas sensors has a nanostructured deposit disposed on the porous silicon layer, wherein the nanostructured deposit is selected from the group consisting of:
• a nanostructured deposit having the characteristic of a hard acid, a nanostructured deposit having the characteristic of an intermediate acid, a nanostructured deposit having the characteristic of a soft acid, a nanostructured deposit having the characteristic of a hard base, a nanostructured deposit having the characteristic of an intermediate base, and a nanostructured deposit having the characteristic of a soft base, wherein the nanostructured deposit used is based on the concept that the nanostructured deposit and the gas have complementary characteristics based on the interactions of two of the following:
• a hard acid, an intermediate acid, a soft acid, a hard base, an intermediate base, and a soft base, where such interaction between the gas and the nanostructured deposit determines the measured impedance change, wherein the greatest impedance change is obtained by using a nanostructured deposit and the gas promoting an interaction that generates the maximum acid-base mismatch;
• measuring the impedance change using one or more of the conductometric porous silicon gas sensors relative to a standard conductometric porous silicon gas sensor;
• and
• obtaining the greatest impedance change using the conductometric porous silicon gas sensor that has the nanoparticle deposit that interact with the gas to produce the maximum acid-base mismatch.

A method of determining the acidic or basic characteristic of a gas, comprising:

• exposing a gas to a plurality of conductometric porous silicon gas sensors, wherein each of the conductometric porous silicon gas sensors is operative to transduce the presence of a gas into an impedance change, wherein the impedance change correlates to the gas concentration,
• wherein the conductometric porous silicon gas sensor has a porous silicon layer, wherein one or more of the conductometric porous silicon gas sensors has a nanostructured deposit disposed on the porous silicon layer, wherein the nanostructured deposit is selected from the group consisting of:
• a nanostructured deposit having the characteristic of a hard acid, a nanostructured deposit having the characteristic of an intermediate acid, a nanostructured deposit having the characteristic of a soft acid, a nanostructured deposit having the characteristic of a hard base, a nanostructured deposit having the characteristic of an intermediate base, and a nanostructured deposit having the characteristic of a soft base, wherein the nanostructured deposit used is based on the concept that the nanostructured deposit and the gas have complementary characteristics based on the interactions of two of the following:
• a hard acid, an intermediate acid, a soft acid, a hard base, an intermediate base, and a soft base, where such interaction between the gas and the nanostructured deposit determines the measured impedance change,
• measuring an impedance change using each of the conductometric porous silicon gas sensors relative to a standard conductometric porous silicon gas sensor, and
• determining if the gas has the characteristic of a hard acid, an intermediate acid, a soft acid, a hard base, an intermediate base, or a soft base, based on the impedance change of the conductometric porous silicon gas sensors.