Transition Metal Nitride Coated with Atomic Layers of Pt as a Low-Cost, Highly Stable Electrocatalyst for the Oxygen Reduction Reaction

Abstract

The main challenges to the commercial viability of polymer electrolyte membrane fuel cells are (i) the high cost associated with using large amounts of Pt in fuel cell cathodes to compensate for the sluggish kinetics of the oxygen reduction reaction, (ii) catalyst degradation, and (iii) carbon-support corrosion. To address these obstacles, our group has focused on robust, carbon-free transition metal nitride materials with low Pt content that exhibit tunable physical and catalytic properties. Here, we report on the high performance of a novel catalyst with low Pt content, prepared by placing several layers of Pt atoms on nanoparticles of titanium nickel binary nitride. For the ORR, the catalyst exhibited a more than 400% and 200% increase in mass activity and specific activity, respectively, compared with the commercial Pt/C catalyst. It also showed excellent stability/durability, experiencing only a slight performance loss after 10,000 potential cycles, while TEM results showed its structure had remained intact. The catalyst's outstanding performance may have resulted from the ultrahigh dispersion of Pt (several atomic layers coated on the nitride nanoparticles), and the excellent stability/durability may have been due to the good stability of nitride and synergetic effects between ultrathin Pt layer and the robust TiNiN support.

Activated Carbon Supported Mo-Ti-N Binary Transition Metal Nitride as Catalyst for Acetylene Hydrochlorination

“…According to the Bragg Equation [31], when the incident angle increased and the wavelength was fixed, this phenomenon implies that the inter planar spacing of Mo2N was increased. This suggests that an atom or ion with an atomic radius larger than that of Mo had been inserted into the Mo2N lattice phase; Ti (0.067 nm) has a larger ionic radius than Mo (0.059 nm) [32]. Furthermore, no other element peaks were detected and also the Ti atom was suitable for this phenomenon, which suggests that a Ti atom was added in the space between the Mo and N atoms.…”

Core–Shell-Structured Low-Platinum Electrocatalysts for Fuel Cell Applications

“…In addition, and of greater importance, researchers have also found that Pt shells can be controllably electrodeposited over noble metal-free TiNiN cores by using the PED (Fig. 12) [329]. Various core-shell-structured electrocatalysts developed through the PED are listed in Table 7.…”

“…Moreover, using DFT calculations, these researchers predicted that NiN@Pt can produce the highest ORR activity among NiN@Pt, CoN@Pt, and FeN@Pt catalysts because FeN and CoN cores impart higher compressive strains to Pt shells than NiN cores, which only provide a slight but moderate compressive force to the Pt shell. In the case of FeN cores, Ding et al [546] reported [329] introduced Ni into TiN cores to synthesize core-shell-structured TiNiN@Pt catalysts. Here, the half-wave potential for the ORR polarization curve of the resulting TiNiN@Pt was 893 mV, which was 16 and 44 mV higher than for TiN@Pt and Pt/C, respectively.…”

Sonochemical Synthesis of Two Dimensional C3N4 Nanosheets Supported Palladium Composites and Their Electrocatalytic Activity for Oxygen Reduction and Methanol Oxidation Reaction

“…Moreover, Pt alone does not present satisfactory activity and stability for the oxygen reduction reaction (ORR) when used as cathode material. [4,5] What is more, high cost and limited available resources of Pt in the earth, and the sluggish kinetics of the ORR at the cathode are the major obstacles to massive commercial application of fuel cells. The design and fabrication of inexpensive, highly active, and stable catalysts of fuel cells is therefore extremely important and remains challenging.…”