Next Level Layered Materials
Layered and two-dimensional materials have emerged as one of the most exciting families of solid-state compounds, due to the plethora of unique physical phenomena found in these materials coupled with advances in the characterization of structure and properties down to the single layer scale. Here, we will describe our efforts in developing new families of these compounds, and our recent discoveries of axis-dependent conduction polarity and hydrogenation catalysis in transition metal-free layered materials. First, electronic materials generally exhibit a single majority carrier type, electrons or holes. We have discovered that NaSn2As2, an exfoliatable van der Waals Zintl phase, simultaneously exhibits p-type behavior in-plane and n-type behavior along the cross-plane direction. We will establish the origin of this phenomenon and its electronic structure fingerprints, show that it exists across many families of layered compounds, and discuss how it can be exploited to create new classes of electronic and thermoelectric devices. Second, inexpensive, transition metal-free intermetallic compounds have received much less attention as heterogeneous catalysts. We will show that BaGa2, a layered Zintl compound known to absorb H2 to form BaGa2H2, effectively catalyzes the hydrogenation of phenylacetylene under modest conditions, with activities within the same order of magnitude as Pd catalysts. These findings open up future explorations of intermetallic hydrogen-absorbing compounds for hydrogen-based catalysis.
