Combustion-based small-scale energy devices have applications in many fields, e.g., portable power devices, sensors, actuators, unmanned aerial microvehicles, microthrusters, and micro-heating devices. In particular, micro-propulsion systems are designed to provide small amounts of thrust ranging from micro-newtons to a few milli-newtons that are used for precise altitude and orbit corrections, drag compensations, and small impulse maneuvers. A variety of micro-propulsion systems have been proposed including field-emission electric propulsion thruster and solid-propellant thruster. In addition to their use in micro-thrusters, microcombustion systems have also been proposed to achieve highly efficient thermal-electric energy conversion. Thermoelectric (TE) systems exploit the unique electrical, semiconducting, and thermal properties of TE materials in order to both achieve and facilitate the processes of heating, cooling, power generation, and waste heat recovery. Such systems directly convert thermal energy into electrical energy by manipulating the flow of charge carriers through electrically conducting materials. This research explores the new physics of combustion at smaller scales with the assistanRce of nanoscale materials for various applications.