Search

Graphene-supported nanoparticles (NPs) are of tremendous interests for a variety of applications recently. In this study, high-surface-area graphene powders are used for loading size-selected Pt colloidal NPs as fuel-cell catalysts for methanol oxidation reaction (MOR). It is found that the adsorption of Pt colloidal NPs on graphene surfaces is dramatically influenced by the process parameter in the mixing process. Specifically, the different solution volumes during the mixing process result in various catalyst morphologies. Pt-graphene (Pt–G) catalyst synthesized through the high-concentration solution system in the mixing process exhibits the densely-packed Pt NPs on graphene surfaces with non-flat wrinkles. Moreover, the high-density Pt NPs in the catalyst give rise to the high MOR current in its forward scan. In other words, this catalyst outperforms all the other catalysts synthesized in the low-concentration solution systems in terms of the MOR current and electrochemical surface area (ECSA). The mass activity of Pt–G-1 catalyst can reach 489.66 mA/mgPt. The appropriate loading of size-selected Pt-based NPs on graphene is significant for the controlled synthesis of catalysts for fuel-cell application.

Carbon black (CB), multi-walled carbon nanotube (MWCNT), and graphene (GN) were examined as catalytic films on the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). GN exhibits the best performance among these materials for the corresponding cell. A composite film of GN/Nafion® was next used as the catalytic film on the CE of a DSSC. Nafion® is demonstrated to be an excellent dispersant for inhibiting the aggregation of GN. A solar-to-electricity conversion efficiency (η) of 8.19% was achieved for the DSSC sensitized by TBA(Ru[(4-carboxylic acid-4′-carboxylate-2,2′-bipyridine)(4,4′-bis(5-(hexylthio)-2,2′-bithien-5′-yl)-2,2′-bipyridine)(NCS)2]), i.e., CYC-B11 dye, which was synthesized by our group, after the optimization of the composition of GN/Nafion®, and an η of 8.89% was exhibited for the cell with a sputtered-Pt (s-Pt) film on its CE under the same conditions. The significance of the cell with the composite film of GN/Nafion® lies in the fact that the expensive Pt is avoided in this case, thereby the cost of the pertinent DSSC was greatly reduced, even though its η (8.19%) is slightly smaller than that of the cell with the s-Pt film (8.89%).

The electrochemical detection of hydrogen peroxide (H2O2) has attracted much attention recently. Meanwhile, the size of nanoparticles which significantly influences electrocatalytic activity is crucial for electrocatalysts. Hence, we prepared five different size-selected Pt/graphene-modified glassy carbon (GC) electrodes to characterize H2O2level via electrochemical measurements. During the preparation of the nanocomposites, size-selected Pt nanoparticles (NPs) with the mean diameter of 1.3, 1.7, 2.9, and 4.3 nm were assembled onto the graphene surfaces. The electrochemical measurement results are size-dependent for Pt NPs when sensing H2O2. When all cyclic voltammogram results from various electrodes are compared, the Pt-1.7 nm/G-modified GC electrode has the highest reduction current, the best detection limit, and the best sensitivity.