Comparison of reduced graphene oxides synthesized chemically with different reducing agents for supercapacitors

The chemical reduction of graphene oxide is an effective method for the synthesis of reduced graphene oxide, having the obvious advantages of low cost and large scale applicability. Our work produced reduced graphene oxide through a simple water bath reduction approach using various reducing agents of N2H4 × H2O, NaBH4, Na2S2O3, HI, and a reference sample without reducing agent at the same reduction temperature and duration time, by which reduced graphene oxides represented as N-RGO, B-RGO, S-RGO, I-RGO, and RGO0 were fabricated. Subsequently, unbonded flexible electrodes based on carbon cloth were fabricated with the reduced graphene oxides mentioned above, whereupon the structure, morphology and electrochemical performance were characterized. The electrochemical results indicate that the order of specific capacitances is N-RGO > B-RGO > S-RGO > RGO0 > I-RGO, while I-RGO’s potential window is wider than that of the others. As a result, N-RGO displays the best electrochemical performance among all reduced graphene oxides, with a specific capacitance as high as 176.0 F × g-1 and 77.8 % of the initial specific capacitance maintained at a high current density of 20 A × g-1.

Small Reduced Graphene Oxides for Highly Efficient Oxygen Reduction Catalysts

We demonstrated highly efficient oxygen reduction catalysts composed of uniform Pt nanoparticles on small, reduced graphene oxides (srGO). The reduced graphene oxide (rGO) size was controlled by applying ultrasonication, and the resultant srGO enabled the morphological control of the Pt nanoparticles. The prepared catalysts provided efficient surface reactions and exhibited large surface areas and high metal dispersions. The resulting Pt/srGO samples exhibited excellent oxygen reduction performance and high stability over 1000 cycles of accelerated durability tests, especially the sample treated with 2 h of sonication. Detailed investigations of the structural and electrochemical properties of the resulting catalysts suggested that both the chemical functionality and electrical conductivity of these samples greatly influence their enhanced oxygen reduction efficiency.

Dual-Modified Cu2S with MoS2 and Reduced Graphene Oxides as Efficient Photocatalysts for H2 Evolution Reaction

Noble metal-free cocatalysts have drawn great interest in accelerating the catalytic reactions of metal chalcogenide semiconductor photocatalyst. In particular, great efforts have been made on modifying a semiconductor with dual cocatalysts, which show synergistic effect of a fast transfer of exciton and energy simultaneously. Herein, we report the dual-modified Cu2S with MoS2 and reduced graphene oxides (Cu2S-MoS2/rGO). The in situ growth of Cu2S nanoparticles in the presence of MoS2/rGO resulted in high density of nanoscale interfacial contacts among Cu2S nanoparticles, MoS2, and rGO, which is beneficial for reducing the photogenerated electrons’ and holes’ recombination. The Cu2S-MoS2/rGO system also demonstrated stable photocatalytic activity for H2 evolution reaction for the long term.