Microwave-assisted one-step synthesis of NiMoO4 and NiMoO4·xH2O/carbon composites and their application in supercapacitors

NiMoO 4 (NMO) and NiMoO 4 ·xH 2 O/carbon composites with rod-like structures were prepared by a simple, fast, and environmentally friendly microwave-assisted method and the effects of different carbon sources on their electrochemical properties were investigated. Glucose and potato starch were used as carbon sources, respectively, and the prepared materials, named NMOG and NMOS, were characterized by powder X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Their electrochemical behaviors were examined by cyclic voltammetry (CV) and constant-current charge-discharge (GCD) techniques. The NiMoO 4 ·xH 2 O/carbon composites exhibited higher specific capacitance than NiMoO 4 due to its low crystallinity and good electrical conductivity of carbon. The specific capacitances were measured at 318.5, 420.5, and 485.3 F g −1 respectively at a current density of 1 A g −1 . In addition, asymmetric supercapacitors (ASCs) were constructed using prepared NMOS-2 as the positive electrode and activated carbon (AC) as the negative electrode. The energy density was 21.62 Wh kg −1 at a power density of 800 W kg −1 . The NMOS-2//AC ASC device showed good cycling stability with 85 % capacity retention after 10,000 cycles. This indicates that NMOS-2 is a promising electrode material for supercapacitors.