Structural integrity versus lateral size: Enhancing graphene-based film materials by reducing planar defects rather than flake boundary

Chemically modified graphene (CMG) bulk films have displayed a large potential in a plethora of applications. Incorporation of large CMG sheets was applied as the major strategy to improve both the electrical and mechanical properties of resulted film materials, whereas the low fabrication yield of high quality large building blocks severely obstruct its scalability. Herein, we evaluated the individual impact of sheet size and structural integrity of CMG building blocks on the performance of film materials, and results show that low structural defects density rather than large size dominates the enhancement of performance. Compared with large building blocks (average area 37.2 mu m(2)), small ones (average area 1.3 mu m(2)) with optimized structural integrity and also higher preparation yield formed films with even higher strength and conductivity (increased by 55% and 120%, respectively). Furthermore, the influence of structural integrity on the material performance was studied via detailed characterization. These results unequivocally impart the importance of structural integrity, and may give instruction on the rational design of materials with excellent performance. (C) 2018 Elsevier Ltd. All rights reserved.