Enhancement of Activity and Development of Low Pt Content Electrocatalysts for Oxygen Reduction Reaction in Acid Media

Abstract

Platinum is a main catalyst for the electroreduction of oxygen, a reaction of primary importance to the technology of low-temperature fuel cells. Due to the high cost of platinum, there is a need to significantly lower its loadings at interfaces. However, then O2-reduction often proceeds at a less positive potential, and produces higher amounts of undesirable H2O2-intermediate. Hybrid supports, which utilize metal oxides (e.g., CeO2, WO3, Ta2O5, Nb2O5, and ZrO2), stabilize Pt and carbon nanostructures and diminish their corrosion while exhibiting high activity toward the four-electron (most efficient) reduction in oxygen. Porosity of carbon supports facilitates dispersion and stability of Pt nanoparticles. Alternatively, the Pt-based bi- and multi-metallic catalysts, including PtM alloys or M-core/Pt-shell nanostructures, where M stands for certain transition metals (e.g., Au, Co, Cu, Ni, and Fe), can be considered. The catalytic efficiency depends on geometric (decrease in Pt–Pt bond distances) and electronic (increase in d-electron vacancy in Pt) factors, in addition to possible metal–support interactions and interfacial structural changes affecting adsorption and activation of O2-molecules. Despite the stabilization of carbons, doping with heteroatoms, such as sulfur, nitrogen, phosphorus, and boron results in the formation of catalytically active centers. Thus, the useful catalysts are likely to be multi-component and multi-functional.

Activation of bimetallic PtFe nanoparticles with zeolite-type cesium salts of vanadium-substituted polyoxometallates toward electroreduction of oxygen at low Pt loadings for fuel cells

“…The performed study showed the highest surface area of Cs x H (3 + n) − x PMo 12 − n V n O 40 when the Cs:HPA ratio is in the range of 2.5 to 3.5 [42]. Dsoke et al [26] also revealed an improved ORR catalytic activity of Pt nanoparticles embedded inside insoluble W-based polyoxometalate (POM) salt, which synthesized from a Keggin-type heteropolyacid. Furthermore, enhancement of catalytic performance of the mixtures of Pt and Pt alloys with such types of co-supports was demonstrated [37][38][39][43][44][45][46][47].…”

“…In fact, automotive and stationary fuel cell applications are typically limited to about 1700 h and 10,000 h of operations, respectively, while at least 5000 h and 40,000 h of continuous operation are required [17,18]. Therefore, in recent years, most of the research efforts have been devoted to reducing the cathode Pt loadings, without loss of performance and durability [19][20][21][22][23][24][25][26][27]. The decrease of Pt loading under 0.2 mg cm −2 maintaining the membrane electrode assembly (MEA) performance of 1000 mW cm −2 , together with low relative humidity (RH) operation and the enhancement of MEA lifetime are some of the important targets aimed at by the US Department of Energy (DOE) for 2020.…”

“…Furthermore, enhancement of catalytic performance of the mixtures of Pt and Pt alloys with such types of co-supports was demonstrated [37][38][39][43][44][45][46][47]. Especially, the Cs 2.5 H 0.5 PW 12 O 40 was reported as excellent mesoporous support for Pt nanoparticles in the preparation of PEM electrodes with low Pt content [26,43,[48][49][50].…”

Inorganic non-carbon supported Pt catalysts and synergetic effects for oxygen reduction reaction

“…2,17,75 In various cases, the oxide supports with improved electrical conductivity still need to be mixed with carbon to fulfill the electrical conductivity requirements. 95 In addition, the catalytic activity of transition metals and the surface OH species of supports also play an influential role in the transformation of adsorbed species.…”

Systematic Study of Effective Hydrothermal Synthesis to Fabricate Nb-Incorporated TiO2 for Oxygen Reduction Reaction

“…With regard to the materials, generally, Pt-based catalysts exhibit remarkable electrocatalytic activity for the ORR [ 8 , 9 , 10 ]; however, they suffer from disadvantages in terms of commercialization, such as high costs and long-term instability [ 11 , 12 , 13 ]. Therefore, alternative materials similar to Pt catalysts, including metal oxides [ 14 , 15 ], metal chalcogenides [ 16 ], and carbon materials [ 17 , 18 ], have been proposed.…”