A novel pseudocapacitance mechanism of elm seed-like mesoporous MoO3−x nanosheets as electrodes for supercapacitors

Pseudocapacitance is induced by surface or near surface redox, ion intercalation or underpotential deposition processes. A given electrochemically active material usually has only one of the above mechanisms. In this study, we synthesized elm seed-like mesoporous MoO3−x nanosheets, which possess both redox and intercalation faradic mechanisms. This novel pseudocapacitance mechanism causes a high capacitance of 1480 F g−1 at 5 A g−1 and outstanding cycling performance where the capacitance does not decay but increases slightly up to 10 000 cycles at a scan rate of 100 mV s−1. Here, we clarified that the tunnel structure of MoO3−x and its special electrochemical kinetics towards H+ generate this mechanism. This faradic mechanism could achieve a higher degree of utilization of the active-sites thus resulting in excellent electrochemical performance.