Toward New Thermoelectrics: Tin Selenide/Modified Graphene Oxide Nanocomposites

New nanocomposites have been prepared by combining tin selenide (SnSe) with graphene oxide (GO) in a simple aqueous solution process followed by ice templating (freeze casting). The resulting integration of SnSe within the GO matrix leads to modifications of electrical transport properties and the possibility of influencing the power factor (S ²σ). Moreover, these transport properties can then be further improved (S, σ increased) by functionalization of the GO surface to form modified nanocomposites (SnSe/GO_mod) with enhanced power factors in comparison to unmodified nanocomposites (SnSe/GO) and "bare" SnSe itself. Functionalizing the GO by reaction with octadecyltrimethoxysilane (C₂₁H₄₆O₃Si) and triethylamine ((CH₃CH₂)₃N) switches SnSe from p-type to n-type conductivity with an appreciable Seebeck coefficient and high electrical conductivity (1257 S·m^-1 at 539 K), yielding a 20-fold increase in the power factor compared to SnSe itself, prepared by the same route. These findings present new possibilities to design inexpensive and porous nanocomposites based on metal chalcogenides and functionalized carbon-derived matrices.