Thermal synthesis of Cu@carbon spherical core–shell structures from carbonaceous matrices containing embedded copper particles

A Cu@carbon (Cu@C) spherical core–shell structure has been synthesized from carbonaceous matrices containing embedded copper particles by thermal treatment at 600 °C under an argon atmosphere. The matrices are prepared by reducing CuCl2 with vitamin C (VC) in the existence of polyacrylamide (PAM) at 180 °C, accompanied by the partial carbonization of VC. It is found that small Cu nanoparticles with diameters of ∼3 nm homogeneously disperse in the carbonaceous matrices. Subsequent thermal treatment at 600 °C under an argon atmosphere leads to the diffusion of these Cu nanoparticles and further carbonization of carbonaceous matrices to form a Cu@C core–shell structure. The core–shell ratio can be controlled by varying the dose of CuCl2, VC, or PAM. It is found that the carbon shell can effectively shield the metallic Cu core from oxidation in the mixed solution of dilute hydrogen peroxide and nitric acid.