Green and eco-friendly chemical exfoliation of two-dimensional nanosheets in the C2H4O3-based system under the assistance of microwave irradiation.

• A green and eco-friendly technical route of two-dimensional nanosheets was proposed. • The conversion from natural graphite to few-layer graphene is ~100%. • No water-washing and effluent-treatment are involved during the exfoliation process. • The graphene paper behaves excellent electrical conductivity to 7.36 × 105 S/m. • The 4-um-thick-graphene paper exhibits a record-high EMI SE value to 61 dB. Eco-friendly exfoliation of two-dimensional nanosheets from their layered bulks is very attracting but still remains a big challenge. Here, we report a novel preparation route of two-dimensional nanosheets through soaking the bulk layered material in the C 2 H 4 O 3 -based chemical exfoliation system followed by microwave irradiation. This route has demonstrated the effective exfoliation of two-dimensional nanosheets (graphene nanosheets, BNNS and MoS 2 NS) from their layered bulks in a green and eco-friendly way. The average layer-number of the obtained graphene nanosheets, BNNS and MoS 2 NS is 4, 6 and 5, respectively, behaving a few-layer feature. Interestingly, when the graphene paper is prepared from the exfoliated graphene nanosheets by simple vacuum filtration and mechanical pressing, its average electrical conductivity is up to 7.36 × 105 S/m and the EMI SE value reaches to 61 dB, both among the highest for the graphene papers reported previously. Since there exists no serious fragmentation of layered materials during the whole exfoliation, the present exfoliation strategy is more competent in preparing the large-sized two-dimensional nanosheets over those conventional green routes. [ABSTRACT FROM AUTHOR]