Microwave Combustion for Modification of Transition Metal Oxides

Abstract

Transition metal oxide has been widely applied in energy conversion, photocatalysis, environmental governance and other electronic devices owing to the properties of low cost, low toxicity and great flexibility in structures and morphology.[1]–[6] However, as one kind of semiconductors, the poor electronic conductivity hinders their practical applications. Very recently, researchers have elucidated that partial reduction by introducing the oxygen vacancies holds a chance to enhance their electric conductivity, promoting the electrochemical and catalytic performance.[7]–[9] While, with various limitations of each method itself, the modification of transition metal oxide with introducing oxygen vacancy by a new method is an effective path to tune their conductivity. In this work, we use microwave combustion system to quickly synthesize reduced metal oxides and graphene hybrid composite in several minutes. Among the as-obtained composite, the reduced orthorhombic Nb 2 O 5 and graphene oxide (rNb 2 O 5 /rGO) has demonstrated great electrochemical performance with a reversible specific capacity of 726.2 C/g at 2 mV/s in organic electrolyte and a capacity retention of 87% after 3000 cycles at 10 A/g. This strategy with such fast reaction time could be a common route to produce oxygen vacancy in oxides, including V2O 5 , WO 3 , TiO 2 etc, and satisfy much more application requirements even for the possibility of industrialization.