Large surface area metal-oxide nanostructures enable substantially enhanced sensitivity for Schottky interface based hydrogen gas sensors. Although it is widely known that operating these gas sensors requires heating to an elevated temperature for optimal sensitivity, the fundamental mechanism that governs this temperature-dependent sensitivity has yet been well understood. In this work, we propose a technique based on thermionic field emission (TFE) theory for analyzing the transport characteristics of Schottky contacted nanostructured gas sensors. Through the fabrication and characterization of a Pt/La2O3 nanobelt Schottky contacted devices, we found the previously unreported correlation between TFE transport and optimal gas sensing temperature. This work augments our understanding of the sensitivity improvement from nanostructures in terms of carrier transport.