The development of novel large-scale synthesis protocols for heteroatom-doped porous carbon nanosheets is highly imperative for wastewater purification and high-performance electrode materials. In the present work, we propose a simple and feasible explosion-assisted activation strategy to fabricate a kind of N-doped porous carbon nanosheet (N-PCNS) at a large scale, in which only lactose and zinc nitrate were used as raw materials. The obtained N-PCNS possesses hierarchical micro- and mesopore nanostructures with a high specific surface area of 879 m2 g-1 while keeping a high nitrogen content of 3.73 at%. The adsorption properties of the N-PCNS were systematically evaluated through adsorption of neutral red (NR) dye. The adsorption capacity of the N-PCNS was as high as 439.6 mg g-1, meanwhile the adsorption process exhibited fine correlation with the Langmuir isotherm and pseudo-second-order kinetic models. As an electrode material for supercapacitors, the specific capacitance of the N-PCNS is up to 263 F g-1 at 1 A g-1 and 194 F g-1 at 20 A g-1, revealing superior rate performance. The capacitance retention after 10 000 cycles at 20 A g-1 is 96%, demonstrating excellent cycling stability. Our work provides an effective approach to achieve the large-scale preparation of high-performance doped carbon materials.