Supplementary information to

Electrical and Mechanical Properties of Poly (dopamine) Modified Copper/Reduced Graphene Oxide Composites

Zhengfeng Jia1,2,3, Haoqi Li2, Yao Zhao2, Laszlo Frazer4, Bosen Qian2, Eric Borguet4, Fei Ren2*, Dmitriy A. Dikin2*

1College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059, PR China2Deparment of Mechanical Engineering, Temple University, Philadelphia 19122, USA3State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 73000, PR China4Department of Chemistry, Temple University, Philadelphia 19122, USA

Figure S1.

Bright field scanning transmission electron image (STEM) of a few representative graphene oxide sheets which were drop casted onto a formvar coated TEM grid from the original water dispersion received from the manufacture, Graphenea. We can see large and small individual sheets which lay flat or partially crumpled and overlapped.

Figure S2.

(a) SEM image of an individual Cu particles (from the batch of Cu/cPDA/rGO coated for 7 hours and heat-treated at 600 0C) with the side attached rGO crumpled sheets decorated with sub-micrometer sized particles.

(b) Bright field scanning transmission electron image (STEM) of a similar sample (from the same batch) where rGO sheets are suspended between large Cu particles carrying a few small particles less than 100 nm in size.

(b)(a)

Figure S3.(a) SEM image of large particle and rGO sheet decorated with sub-micrometer sized particles,(b) and (c) EDS spectra collected from small particles on rGO sheet (area 5) and from the side of a large Cu particles (area 6).

According to the recorded Spectrum 5 there is much more carbon in that area compare to the area 6. However, it is impossible to draw a definite conclusion since, to a large extend, carbon signal may also originate from the polymer adhesive tape which holds large Cu particles on the SEM sample holder.

Area 5

Area 6

C 54 at%Cu 44 at%O 1.7 at%

Cu 70.5 at%C 28.4 at%O 1.0 at%

(a)

(b)

(c)