▎ 摘　　要

In this work, a three-dimensional (3D) graphene/manganese dioxide nanocomposite (PGA/MnO2) with a hierarchically porous structure was prepared by facile steam activation and MnO2 deposition strategies. The as-prepared PGA/MnO2 exhibited a 3D architecture with a high surface area of 490 m(2) g(-1). By characterization of morphology and structure of PGA/MnO2, MnO2 nanoparticles with small size (5-10 nm) were loaded on interconnected graphene sheets. Benefiting from the 3D porous nanostructure as well as the synergetic action between MnO2 and graphene, the PGA/MnO2 sample showed good adsorption ability for various metal ions (Pb2+, Cu2+, and UO22+). Especially, the adsorption capacity of Pb2+ on PGA/MnO2 can reach 247.3 mg g(-1). The PGA/MnO2 with the porous structure also exhibited good capacitive deionization performance and had a NaCl adsorption capacity of up to 15.3 mg g(-1) in a 500 mg L-1 solution. These results demonstrate that the resultant porous PGA/MnO2 is a promising adsorbent for water treatment application.