More stable structures lead to improved cycle stability in photocatalysis and Li-ion batteries

A simple combustion method was used to synthesize stable network-like nanostructures. Take two kinds of iron oxides for example. The Fe ₂O₃ network nanocrystal with an average diameter of 50 nm composed of Fe grains ∼5-10 nm in diameter was firstly obtained. It showed an enhanced photocatalysis and cycle stability (∼50% after 4 cycles) compared with the commercial NPs (only 24% after 3 cycles) in the degradation of RhB. The structure of the sample could remain even after 4 photocatalytic cycles, explaining why the sample had an improved cyclability. Next, Fe ₃O₄/C network nanostructure was synthesized using Fe ₂O₃ sample as precursor. One Fe₃O₄ sample with the thickest carbon layers (∼8 nm) was more stable, compared to other two samples with ∼2 nm and ∼5 nm carbon layers. The related HRTEM image exhibited the outer layers of the sample had become onion-like structure from amorphous carbon, explaining an excellent performance of a capacity of 400 mAh g^-1 after 90 cycles even at a high current rate of 2 C. These two kinds of iron oxide with stable network-like nanostructure by combustion method showed probable applications in photocatalytic and electrochemical fields.