Low-Temperature Combustion Synthesis of Metals and Metal Oxides via Isobutylene-Generating Complexing Agents

Solution combustion synthesis (SCS) is a low-temperature synthesis technique leveraging a highly exothermic combustion reaction between a metal complexed by an organic fuel and oxidant (e.g., nitrate) to generate metals and metal compounds such as oxides, nitrides, and carbides at reduced applied temperatures compared to conventional solution methods. However, many ideal hydrocarbon fuels for low-temperature combustion processes are too volatile and noncoordinating to metal cations in solution, making them poorly suited for SCS. Here, we present SCS complexing agents, which contain t-butyl ester functionality capable of generating isobutylene in situ at low applied temperatures, which acts as a potent fuel in the combustion process. We form four important oxides and metal/oxide combined nanostructures: InOx, MnOx, NiOx, and CoOx at applied temperatures <150 °C including the formation of InOx at <80 °C which is, to our knowledge, the lowest purely heat-initiated SCS reaction observed to date. This work reveals that isobutylene-generating fuels, particularly for the indium cation, are a powerful tool for applications demanding oxides at low formation temperatures.