One‐Step Synthesis of Single‐Layer MnO2 Nanosheets with Multi‐Role Sodium Dodecyl Sulfate for High‐Performance Pseudocapacitors

A template‐free, one‐step and one‐phase synthesis of single‐layer MnO 2 nanosheets has been developed via a redox reaction between KMnO 4 and sodium dodecyl sulfate (SDS). The successful formation of single‐layer MnO 2 nanosheets has been confirmed by the characteristic absorption around 374 nm and the typical thickness of ~0.95 nm. The slow redox reaction controlled by the gradual hydrolysis of SDS is found to be the key factor for the successful formation of single‐layer nanosheets. SDS not only serves as the precursor of dodecanol to reduce KMnO 4 , but also aids the formation of single‐layer MnO 2 nanosheets as a structure‐inducing agent. The resultant single‐layer MnO 2 nanosheets possess superior specific capacitance, which can be attributed to the extended surface and high porosity of MnO 2 nanosheets on the electrode. The MnO 2 nanosheets also show excellent durability, retaining 91% of the starting capacitance after 10 000 charge/discharge cycles. Moreover, the symmetric pseudocapacitor based on the synthesized single‐layer MnO 2 nanosheets exhibits a high specific capacitance, indicating great potential for real energy storage. Therefore, it has been demonstrated for the first time that a single readily available reagent, SDS, can play multiple roles in reducing KMnO 4 to conveniently yield single‐layer MnO 2 nanosheets as a high‐performance pseudocapacitive material.