Aggregation reduction of atomic force microscopy sample preparation of reduced graphene oxide nanosheets

Aggregation, occurring in the preparation of atomic force microscopy samples, usually results in difficulties for morphologic observation and nanosheet-thickness analyses of the reduced graphene oxide nanosheets prepared by chemical reduction of exfoliated graphite oxide. In this paper, a simple method, primarily based on nitrogen-blow, was proposed for reducing the degree of aggregation occurring in atomic force microscopy sample preparation. The aggregation degree was characterized by the ratio of the region covered by overlapping nanosheets to that by single-layer nanosheets. Atomic force microscopy imaging results showed that the aggregation degree (20.5%) of the sample prepared by our proposed method was obviously lower than that (90.7%) by air-dry method. The possible mechanism analyses indicated that this obvious change may be attributed to the elimination of droplet-evaporation step entailed in air-dry method from our proposed method.