The hollow activated carbon nanomesh (PCACM) with a hierarchical porous structure is derived from biowaste-poplar catkins by in-situ calcination etching with Ni(NO3)(2).6H(2)O and KOH in N-2 flow combined with an acid dissolution technique. This procedure not only inherits the natural tube morphology of poplar catkins, but also generates a fascinating nanomesh structure on the walls. PCACM possesses a large specific surface area (S-BET = 1893.0 m(2) g(-1)) and high total pore volume (V-P = 1.495 cm(3) g(-1)), and displays an exciting meso-macoporous structure with a concentrated pore size distribution of 4.53 nm. The specific capacitance of PCACM is as high as 314.6 F g(-1) at 1.0 A g(-1) when used as the electrode materials for supercapacitor. Furthermore, the symmetric supercapacitor of PCACM with 1.0 M Na2SO4 solution as the electrolyte displays a high energy density of 20.86 Wh kg(-1) at a power density of 180.13 W kg(-1) within a wide voltage rage of 0-1.8 V, which is comparable or even obviously higher than those of other biomass derived carbon reported. It is noteworthy that PCACM also exhibits superior cycling stability and coulombic efficiency. The excellent electrochemical behaviors enable PCACM to be a promising electrode material for supercapacitors. (C) 2017 Elsevier B.V. All rights reserved.