Our research efforts are centered on the synthesis and characterization of novel inorganic/solid state materials with unique and tunable properties, particularly nanomaterials. The research is highly interdisciplinary, with the aim to develop a fundamental understanding of how structure, particle size, and material physical properties are related in order to advance technologies such as energy conversion, sensors, environmental remediation, and catalysis. Specifically, we focus on developing new synthetic methods that will permit formation of nanoparticles with new and more complex chemistries than those we presently know how to make, and on developing methods for linking nanoparticles together with each other, or to organic molecules/polymers, to create new functional materials.
Current Projects
3-D assemblies of nanoparticles through sol-gel chemistry
In order for nanoparticles to be implemented in solid state devices, we need methodologies that permit them to be linked together – with each other, or to another nanocomponent – while still maintaining the unique size-dependent properties of the individual building blocks. Sol-gel methodologies represent a tried-and-true way of linking particles together in solution, without intervening ligands, into open 3-D architectures with through-connected pore volumes. These gels can be dried and subsequently processed to form dense nanostructures (xerogels) or highly porous nanostructures (aerogels). This approach has been extensively exploited for oxide materials, but these tend to be insulators or large bandgap semiconductors, limiting applications. We have established sol-gel strategies that can be applied to other materials, most notably metal chalcogenides, for the preparation of electronically linked semiconducting nanostructures with bandgaps from the IR to the UV. We are investigating the suitability of these materials for photovoltaic, sensing, photocatalytic and environmental remediation applications.
Synthesis and characterization of discrete nanoparticles of transition metal pnictides (pnicogen = Group 15 element) for catalysis and magnetic refrigeration
Due to the presence of accessible d-electrons, the phase diagram of transition-metal pnictides is rich with structures and stoichiometries. These phases exhibit a wide range of magnetic and electronic properties of fundamental and practical interest including superconductivity, ferromagnetism, magneto-striction, magneto-optics, and semiconductivity, and are also of interest as thermo catalysts for hydrodesulfurization (HDS) of fuels and electrocatlysis for water splitting. The introduction of size control as a synthetic variable is has produced a unique class of materials with properties that are tunable with size. We have developed arrested precipitation methods that enable us to form narrow polydispersity nanoparticle samples of phases including FeP, Fe2P, MnP, MnAs and Ni2P and are now extending these systems into ternary and quaternary systems. In addition to developing new synthesis methods, we have also been extensively exploring how size limitation impacts magnetic properties relevant to magnetic refrigeration, catalytic activity for hydroprocessing of fossil fuels, and electrocatalytic water splitting.
Currently we are collaborating with the following groups:
Prof. Jier Huang (Marquette U., Chemistry) – Spectroscopic Studies
Prof Zhenfei Liu (WSU, Chemistry) – Computational Modeling
Prof. Long Luo (WSU, Chemistry) – Electrochemistry/Sensing
Prof. Boris Nadgorny (WSU, Physics) – Magnetic Characterization