In this work, nitrogen was in situ doped into the spinel ZnMn 2 O 4 material via a one-step gel-combustion technique using various amounts of urea fuel. Despite the impurity ZnO and MnO phases at the higher amounts of urea fuel, the single-phase ZnMn 2 O 4 material was crystallized following the combustion reaction without the need for further treatment. The ZnMn 2 O 4 material synthesized at a molar ratio of urea fuel to total metal nitrate of 1:1 showed oxygen vacancies. However, 3.26 and 4.99 at.% N dopants were in-situ doped at a molar ratio of 2:1 and 3:1, respectively, as tracked by X-ray photoelectron and photoluminescence spectroscopy techniques. The combusted ZnMn 2 O 4 powders exhibited a porous microstructure, with the specific surface area and pore volume, decreasing from 78.6 to 12 m 2 g −1 and from 0.27 to 0.04 cm 3 g −1 , respectively, with an increase in the urea fuel content. The proper amount of N-dopants in the ZnMn 2 O 4 cathode material increased the charge storage capability, including a high-rate capability of 16% with increasing the current density from 50 to 1500 mA g −1 and a high capacity retention of 76% at 1000 mA g −1 over 500 cycles. • N doped ZnMn 2 O 4 powders were prepared by gel-combustion method. • -The combusted ZnMn 2 O 4 powders exhibited a porous microstructure with a specific surface area of 78.6 m 2 g −1 . • −3.26 at.% N-dopant in the ZnMn 2 O 4 cathode material led to a rate capability of 16% and a capacity retention of 76%.
Nasrinpour et al. (Sun,) studied this question.