Synthesis of 3D graphene/MnO2 nanocomposites with hierarchically porous structure for water purification

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 m2 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.