A multi-dimensional project is proposed following two interwoven research thrusts, 1) new approaches to materials design and manufacturing using data analytics combined with modeling and simulation and 2) the efficient application of these materials for the rapid design of sensitive interfaces, and their application to meet manufacturing challenges. This project will seek to apply a recently developed principle, the IHSAB interaction model, representing a general design criteria for the manufacture of materials with the ability to respond as highly sensitive nanosensors that are robust and can work in deleterious environments with ppb level sensitivity1,2. While our initial goal is the optimization of nanostructure directing interfaces to achieve a general approach to chemical selectivity, a key challenge in chemical sensing, opportunities may also exist to more general problems in catalytic chemistry.
Experimental and modeling groups in physics and chemical engineering will combine to develop a new approach for the a-priori design of interfaces to produce highly efficient chemical sensors and catalysts. This effort will link chemical selectivity, the balance of physisorption and chemisorption, and their associated impact on electron dynamics at doped semiconductor and nanowire interfaces with the mechanism of sensor response and catalyzed chemical transformations. The basic tenants of acid/base chemistry (the ability of bases to donate electrons and acids to seek electrons) and semiconductor physics provides a rational approach to control the coupling of analyte/interface interactions with the properties of an extrinsic semiconductor to facilitate a novel approach to efficient and controllable solid-gas (liquid) interfacial processes. Nanopore coated microchannels will be used to facilitate optimized analyte diffusion for the subsequent fractional deposition of select nanostructures decorating the microchannel. The nanostructures will be carefully chosen to guide a controlled balance of physical and chemical interactions at the decorated doped semiconductor interface. Within this framework, the choice of sensor response guides the choice of heterogeneous catalytic sites. The selection of the nanostructures dictates the nature of electron dynamics at the interface and the coupling to the majority charge carriers of the semiconductor. This coupling requires the integration of synthesis, characterization, device development, and modeling.
The modeling effort will probe the molecular/surface interactions and chemical rearrangements responsible for the acid/base (Lewis and possibly Brönsted) chemistry and interpret experimentally observed interactions with and without the semiconductor support. These studies will be used to aid the evaluation of the mechanistics of the IHSAB model. A goal is to determine the critical energetic features of the IHSAB concept in terms of analyte interactions with undoped and doped nanoparticles and the semiconductor interface. Parameters that must be evaluated both experimentally and theoretically in order to gain a full picture of the IHSAB model include the band gaps and the effect of the nanoparticle-interface interaction and chemistry at these band gaps. A key emphasis will be to better characterize the change in electronic character of the sensing system when it interacts with an analyte as it injects or removes charge from the semiconductor interface to change the conductometric characteristics of this interface. This includes the orbital/band energies above and below the orbitals at the band gap. The modeling will thus be used to develop correlations with the experimental measurements developing new approaches to understand the interaction of the analytes with nanostructure decorated extrinsic semiconductor surfaces.
1. James L. Gole and Serdar Ozdemir, ChemPhysChem., 11,2573-2581 (2010). James L. Gole, Eddie C. Goode, and William Laminack, ChemPhysChem, 13,549-561(2012), (Doi.org/10.1002/cphc.201100712).
2. Gole, J. L.; Laminack, W. I. in “Chemical Sensors: Simulation and Modeling,” Volume 3–Solid State Sensors, pp 87-136, Ed. G. Korotcenkov, Momentum Press, New York, USA.