Huanqiao Li

A high-performance electrocatalyst for oxygen reduction based on reduced graphene oxide modified with oxide nanoparticles, nitrogen dopants, and possible metal-N-C sites

Non-noble metal (NNM) electrocatalysts with performances comparable with or superior to Pt are highly desirable for fuel cells and metal-air batteries, but remain rare. Herein, we report a new NNM electrocatalyst derived from reduced graphene oxide (rGO), dual nitrogen-containing ligands, and iron and cobalt salts. Remarkably, the onset potential and half-wave potential (E1/2) of the obtained electrocatalyst shifts 5 and −23 mV, respectively, relative to commercial Pt/C at a standard loading of 20 μgpt cm−2 toward an oxygen reduction reaction (ORR) in alkaline solutions. Additionally, the electrocatalyst is much better than the Pt/C in terms of durability and tolerance to methanol.

Light-controlled synthesis of uniform platinum nanodendrites with markedly enhanced electrocatalytic activity

AbstractWe report a fast in situ seeding approach based on zinc(II) porphyrin (ZnP) under white light irradiation, leading to uniform spherical platinum nanodendrites with tunable sizes. The platinum nanodendrites exhibit significantly improved electrocatalytic activities toward oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) compared with commercial platinum black.n

One-step synthesis of carbon-supported foam-like platinum with enhanced activity and durability

Carbon black nanoparticles localized in-between liposomal bi-layers provide a unique reaction environment that permits one-step synthesis of carbon-supported foam-like platinum (Pt foam/C) in aqueous solution under ambient conditions. The obtained Pt foam/C was readily purified by simple washing with water and chloroform at room temperature. Unlike commercial Pt/C composed of quasi-spherical nanoparticles, Pt foam/C consists of convoluted dendritic nanosheets. Interestingly, Pt foam/C demonstrated both improved durability and activity toward oxygen reduction reaction (ORR). The improved durability is because of the formation of metastable nano-holes among dendritic branches of Pt foam/C under ripening, preserving the surface area. The activity enhancement of Pt foam/C can be attributed to predominantly exposed Pt {1,1,0} planes that possess the highest ORR activity among all low-indexed Pt crystalline planes. Nano-scale Pt primarily enclosed by {1,1,0} planes has not been reported previously.

Hierarchically ordered arrays with platinum coated PANI nanowires for highly efficient fuel cell electrodes

The fabrication of a novel electrode architecture with multi-scale orderliness is an effective strategy to enhance Pt utilization and decrease the mass transport polarization loss of proton exchange membrane fuel cells (PEMFCs). Here we report a hierarchically well-defined electrode with Pt nanowhiskers on aligned nanowires by a magnetron sputtering method. With the crystallographically preferential growth of Pt (111) facets, in association with the electron modification effects of PANI on Pt nanowhiskers, the electrode achieves outstanding electrochemical activity towards the oxygen reduction reaction (ORR) with a 2.19-fold enhancement of the specific activity and a similar mass specific activity at 0.9xa0V (vs. the RHE), compared to the state-of-the-art Pt–C electrode. The PEMFC fabricated with the Pt–PANI-GDL electrode shows excellent performance with a peak power density of 542 mW cm−2, and a cathode mass specific power density of 5.7 W mgPt−1, which is 39% greater than that of PEMFCs equipped with a Pt–C electrode for enhanced electrochemical activity and mass transport.