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Search for a Platinum metal-free catalyst for Proton Exchange Membrane Fuel Cells (PEMFCs) is a concern to scientists as the Pt-catalyzed electrode comprises about 45% of the entire fuel cell stack cost. Due to layered structure, Two-dimensional (2D) MoS2 nanostructured materials have recently drawn attention as effective catalysts for oxygen reduction reaction (ORR). The 1T-phase of MoS2 (1T-MoS2) has higher electronic conductivity than the 2H-phase (2H-MoS2); high surface area 1T-MoS2 can have high electrocatalytic activity towards PEFFCs. Here, we report hydrothermally synthesized 2H-MoS2 and solvothermally synthesized mixed 1T/2H-MoS2 phases as a catalyst for ORR in PEM Fuel Cells. Owing to the high BET-specific surface area, hybrid 1T/2H-MoS2 showed better ORR activity than 2H-MoS2. The limiting current density of the 1T/2H-MoS2 hybrid structure is ‒7.1 mA cm−2 compared to Pt/C (‒8.2 mA cm−2) at 1600 rpm. The Tafel slope values of 2H-MoS2, 1T/2H-MoS2, and Pt/C are 92.7 mV dec−1, 57.5 mV dec−1, and 39.3 mV dec−1, respectively. The electron transferred during ORR are 3.8 and 1.8, respectively, for 1T/2H-MoS2 and 2H-MoS2 (in 0.1 M KOH) ; suggesting less formation of undesirable peroxide formation than 2H-MoS2. The 1T/2H-MoS2 displays better electrochemical durability compared to 2H-MoS2 (after 2000 CV cycles). [ABSTRACT FROM AUTHOR]

The weak interaction between common carbon support and Pt nanoparticles results in low efficiency for the oxygen reduction reaction (ORR) with high overpotentials, which greatly limits the practical application of proton exchange membrane fuel cells. Employing strong metal–support interaction (SMSI) is a promising method for tuning the electronic structure of Pt to boost the ORR, accompanied by rapid improvement in durability. Herein, titanium carbide (TiC) was grown on the surface of carbon black by the sol–gel method coupled with high-temperature treatment (denoted as TiC-C). Based on the SMSI that occurred between TiC and Pt, the obtained Pt/TiC-C catalyst exhibits higher mass ORR activity, which is twice that of the commercial Pt/C-JM under the same conditions. In addition, the Pt/TiC-C exhibits superior durability relative to the Pt/C-JM by preventing the aggregation and dissolution of Pt nanoparticles during the ORR process. [ABSTRACT FROM AUTHOR]

The development of active and durable proton exchange membrane fuel cell catalysts with high loading (ca. 40%) is critical for the commercialization of hydrogen fuel cells. Herein we report on the synthesis of a novel Pt/C catalyst using a novel bowl-like broken hollow carbon sphere (and N-doped sphere) support (carbon shell thickness ~ 4.6 nm). Highly dispersed Pt nanoparticles (dPt ~ 4 nm) were deposited on both supports and within the carbon shell. The Pt particles in the pores were exposed on both sides of the shell, while the shell porosity ensured pore confinement of the Pt. Both catalysts exhibited high electrochemical surface areas (60–65 m2 g−1) and cycling durability (6000 cycles) that was superior to a commercial benchmark Pt/C catalyst. These studies indicate that high loadings of confined small Pt particles on both sides of thin interconnected carbons can lead to high oxygen reduction reaction activities and durability. [ABSTRACT FROM AUTHOR]

Abstract: Atomic layer deposition (ALD) was used to modify two different types of carbon black-based Pt oxygen reduction catalysts with protective TiO2 nanostructures to increase catalyst durability. Rates of ALD growth and the structure of deposited TiO2 were observed to be highly dependent on oxygen content of the catalyst substrate. Electrochemical durability was enhanced with the addition of TiO2 ALD nanostructures, with up to 70% retention in mass activity measured over accelerated durability testing. High-temperature treatment of the top-performing ALD catalyst, which was found to promote structural rearrangement of the TiO2 and Pt phases into hybrid nanoparticles, yielded a twofold increase in activity but was detrimental to durability.Graphical Abstract: [ABSTRACT FROM AUTHOR]