A facile template approach for the synthesis of mesoporous Fe3C/Fe-N-doped carbon catalysts for efficient and durable oxygen reduction reaction

One-pot synthesis of three-dimensional Pt nanodendrites with enhanced methanol oxidation reaction and oxygen reduction reaction activities

The high cost of Pt-based catalysts impedes the practical large-scale commercial application of fuel cells. Controlling the morphology of Pt nanostructure is one of the most promising approaches to promote the electrocatalytical activity and stability toward methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). Herein, we report a facile method for the synthesis of Pt nanodendrites consisting a dense array of dendrites using K₂PtCl₄ as metal resource, L-ascorbic acid as reducing agent and hexadecyltrimethylammonium chloride as capping agent in aqueous solution at 96 °C for 30 min. Owing to the novel structure, the obtained Pt nanodendritic electrocatalyst exhibites superior MOR catalytic performance and particularly long-term stability both in acid and alkaline conditions. the Pt nanodendrites also exhibited a higher half wave potential of 0.86 V and lower tafel slope of 51.69 mV dec^-1 when compared with 20% Pt/C (0.83 V, 93.55 mV dec^-1) in acid conditions toward ORR. This work provides a promising way for the rational design of efficient and robust catalysts for sustainable energy conversion.

In situ durability of various carbon supports against carbon corrosion during fuel starvation in a PEM fuel cell cathode

In this study, the degradation of different cathode carbon supports is investigated in proton exchange membrane fuel cells (PEMFCs). A platinum catalyst is synthesized using various carbon supports, such as Vulcan XC-72, graphite nanopowder and carbon nanotube, which are evaluated based on the fabrication of membrane electrode assemblies. During the startup and shutdown of PEMFCs, the individual electrode potential can be measured in situ using a dynamic hydrogen electrode. The cathode potential increases instantaneously to 1.4 V in one attempt, when H₂/air boundaries are developed on the anode side during the fuel starvation, leading to significant carbon corrosion. The corrosion rates of various carbon supports are calculated from the concentration of gases, such as CO₂, CO and SO₂, emitted from the cathode outlet, measured directly in situ by Fourier transform infrared gas analysis. The carbon nanotube-supported Pt catalyst shows the best performance against carbon corrosion during fuel starvation, compared to commercial Pt/C catalyst and other types of carbon supports.