▎ 摘　　要

Metal ions (Al3+ and Co2+) co-doped alpha-Ni(OH)(2)/graphene hybrid materials had been successfully synthesized by a facile chemical co-precipitation route. X-ray diffraction (XRD) patterns revealed the successful phase transmission from beta-Ni(OH)(2) to alpha-Ni(OH)(2) after Al3+ doping and the continuously enlarged interlayer distance of alpha-Ni(OH)(2) after subsequent Co2+ doping. Due to its large interlayer distance, mesoporous structure and highly conductively graphene (GNS), the as-obtained Al-Co co-doped alpha-Ni(OH)(2)/GNS composite (Al-Co-Ni/GNS) showed an ultrahigh specific capacitance of 2257 F g(-1) at 2 mV s(-1) as well as good cycling stability with 77% of the initial capacitance retention after 1000 cycles in 6 M KOH aqueous solution. (C) 2014 Elsevier Ltd. All rights reserved.