It is a challenge to make good use of biomass resources for energy storage applications. In this study, wheat straw, a common agricultural waste, is used as the precursor for synthesizing biomass-derived porous carbon (BPC), which is then decorated with Fe2O3 ultrathin film through a facile methodology. Benefiting from the hierarchical structure and synergetic effect, the BPC/Fe2O3 nanocomposite exhibits high performances for supercapacitors, i.e., large specific capacitance up to 987.9 F g(-1) (219.5 mAh g(-1)) at a current density of 1 A g(-1), great rate capability (423.8 F g(-1) at 30 A g(-1)), and superior cyclability (82.6% capacitance retention after 3000 cycles). In addition, an aqueous asymmetric supercapacitor (ASC) is assembled with BPC/Fe2O3 as the anode material. The ASC delivers high specific energy of 96.7 Wh kg(-1) and high specific power of 20.65 kW kg(-1), making it one of the best performed ASC devices reported to date. The results of this study manifest great potential of constructing BPC/metal oxide heterostructures for efficient energy storage devices. (c) 2017 Elsevier Ltd. All rights reserved.