Pt-based Electrocatalysts Research Articles

Tunable Pt-Ni Interaction Induced Construction of Disparate Atomically Dispersed Pt Sites for Acidic Hydrogen Evolution.

Developing cost-effective Pt-based electrocatalysts for the hydrogen evolution reaction (HER) is highly urgent. Herein, we report novel electrocatalysts with individually dispersed Pt active sites and tunable Pt-Ni interaction decorated on carbon-wrapped nanotube frameworks (Pt/Ni-DA). Pt/Ni-DA exhibits superior HER performance at low Pt concentrations with an ultralow overpotential of 18 mV at 10 mA cm-2 and an ultrahigh mass activity of 2.13 A mgPt-1 at an overpotential of 50 mV, which is about four times higher than that of commercial Pt/C. X-ray absorption fine structure (XAFS) confirms the extension of Pt from the Ni surface to the Ni bulk phase. Mechanistic research and density functional theory (DFT) calculations collectively reveal that the dispersibility and distribution of Pt atoms in Ni regulate the electronic configuration of Pt sites, optimizing the binding energy of reaction intermediates and facilitating electron transfer during the HER process. This work highlights the importance of the electronic structure alternation through the accommodation effect toward enhanced catalytic performance in HER.

Engineering composition-varied Au/PtTe hetero-junction-abundant nanotrough arrays as robust electrocatalysts for ethanol electrooxidation

Pt-based multi-metallic electrocatalysts containing hetero-junctions are found to have superior catalytic performance to composition-equivalent counterparts. However, in bulk solution, controllable preparation of Pt-based hetero-junction electrocatalyst is an extremely random work owing to the complexity of solution reactions. Herein, we develop an interface-confined transformation strategy, subtly achieving Au/PtTe hetero-junction-abundant nanostructures by employing interfacial Te nanowires as sacrificing templates. By controlling the reaction conditions, composition-varied Au/PtTe can be easily obtained, such as Au75/Pt20Te5, Au55/Pt34Te11, and Au5/Pt69Te26. Moreover, each Au/PtTe hetero-junction nanostructure appears to be an array consisting of side-by-side Au/PtTe nanotrough units and can be directly used as a catalyst layer without further post-treatment. All Au/PtTe hetero-junction nanostructures show better catalytic activity towards ethanol electrooxidation than commercial Pt/C because of the combining contributions of Au/Pt hetero-junctions and the collective effects of multi-metallic elements, where Au75/Pt20Te5 exhibits the best electrocatalytic performance among three Au/PtTe nanostructures owing to its optimal composition. This study may provide technically feasible guidance for further maximizing the catalytic activity of Pt-based hybrid catalysts.

Ethylene glycol diethyl ether accelerated in-situ growth of Pt/Ni(OH)2 nanosheets on Ni foam for efficient alkaline hydrogen evolution reaction

The hydrogen evolution reaction (HER) activity of Pt-based electrocatalysts in alkaline solution is typically limited by the rate of water dissociation. Herein, we report a facile one-step strategy in the synthesis of Pt/Ni(OH)2 heterojunction for enhanced HER activity. Ultrathin Ni(OH)2 nanosheets decorated with uniformly dispersed Pt nanoparticles at average sizes of 2.2 nm are in-situ grown on nickel foam (NF) with binder-free feature under mild conditions due to induction by ethylene glycol diethyl ether, even without adding extra Ni2+ sources. The synthesized Pt/Ni(OH)2/NF shows superior HER activity in 1.0 M KOH solution, achieving low overpotentials of 42, 91, and 114 mV at current densities of 10, 100, and 200 mA cm−2 and outstanding durability for 25 h at 25 mA cm−2 without noticeable Pt agglomeration. This work offers a mechanistic insight into one-step fabrication of Pt/Ni(OH)2-based catalyst with high activity and stability for HER.

Introduction of Surface Modifiers on the Pt-Based Electrocatalysts to Promote the Oxygen Reduction Reaction Process.

The design of Pt-based electrocatalysts with high efficiency towards acid oxygen reduction reactions is the priority to promote the development and application of proton exchange membrane fuel cells. Considering that the Pt atoms on the surfaces of the electrocatalysts face the problems of interference of non-active species (such as OHad, OOHad, CO, etc.), high resistance of mass transfer at the liquid-solid interfaces, and easy corrosion when working in harsh acid. Researchers have modified the surfaces' local environment of the electrocatalysts by introducing surface modifiers such as silicon or carbon layers, amine molecules, and ionic liquids on the surfaces of electrocatalysts, which show significant performance improvement. In this review, we summarized the research progress of surface modified Pt-based electrocatalysts, focusing on the surface modification strategies and their mechanisms. In addition, the development prospects of surface modification strategies of Pt-based electrocatalysts and the limitations of current research are pointed out.

A facile strategy to prepare FeNx decorated PtFe intermetallic with excellent acidic oxygen reduction reaction activity and stability

The construction of low-Pt-content intermetallic on carbon supports has been verified as a promising method to promote the activity of the oxygen reduction reaction (ORR). In this study, we have developed a simple and effective strategy to obtain a well-designed CNT-PtFe-PPy precursor. This precursor contains modulated Pt- and Fe-based content dispersed in polypyrrole (PPy) chain segments, which are in-situ generated on the templates of carbon nanotubes (CNTs). Subsequent pyrolysis of the CNT-PtFe-PPy precursor produces a CNT-PtFe@FeNC catalyst, which contains both Fe-Nx and PtFe intermetallic active sites. Due to the highly efficient dispersion of active species, the CNT-PtFe@FeNC electrocatalyst displays a 9.5 times higher specific activity (SA) and 8.5 times higher mass activity (MA) than those of a commercial Pt/C catalyst in a 0.1 M HClO4 solution. Additionally, these results, combined with excellent durability (the SA and MA maintained 94 % and 91 % of initial activity after a 10-k cycle accelerated durability test), represent among the best performance achieved so far for Pt-based ORR electrocatalysts. Furthermore, density functional theory (DFT) calculations revealed that the presence of Fe-N4 species reduces the adsorption energy between the PtFe intermetallic compound and OH*, accelerating the ORR process.

Pt-C interactions in carbon-supported Pt-based electrocatalysts.

Carbon-supported Pt-based materials are highly promising electrocatalysts. The carbon support plays an important role in the Pt-based catalysts by remarkably influencing the growth, particle size, morphology, dispersion, electronic structure, physiochemical property and function of Pt. This review summarizes recent progress made in the development of carbon-supported Pt-based catalysts, with special emphasis being given to how activity and stability enhancements are related to Pt-C interactions in various carbon supports, including porous carbon, heteroatom doped carbon, carbon-based binary support, and their corresponding electrocatalytic applications. Finally, the current challenges and future prospects in the development of carbon-supported Pt-based catalysts are discussed.

One-pot hydrothermal synthesis of Pt–TiO2–Carbon as a highly active and stable electrocatalyst for oxygen reduction reaction

Energy conversion from chemical to electrical energy through electrochemical processes using fuel cells is a promising advanced technology to address global environmental issues. However, the development of cathode materials for proton exchange membrane fuel cells (PEMFCs) still faces challenges due to their practical requirements for activity and stability. Introducing oxides into the electrocatalysts is an important way to improve performance. Here, we propose a one-pot hydrothermal synthesis to load Pt and TiO2 nanoparticles (NPs) onto the treated carbon (TC). Through the TiO2 reconciliation between the Pt NPs and the carbon support, the tightly bound Pt–TiO2–TC electrocatalyst shows excellent activity and stability in the oxygen reduction reaction (ORR) due to the strong electronic interaction. At 0.9 V vs. reversible hydrogen electrode, the Pt–TiO2–TC electrocatalyst has about twice the specific activity (SA) and mass activity (MA) of commercial Pt/C. Moreover, the decline of Pt- SA and MA in Pt–TiO2-TC after the accelerated durability test (ADT) was 4.2% and 12.3%, respectively. Therefore, we strongly recommend hybrid metal-oxide-carbon materials with high conductivity, electronic interaction, and carbon corrosion resistance as support materials for Pt NPs to develop Pt-based electrocatalysts for fuel cell applications.

Pt-Based Electrocatalyst Modified by CsH2PO4/SiP2O7 for Electrochemical Oxidation of NH3 to H2 in Solid Acid Electrolysis Cell

Ammonia (NH3) has received much attention as a hydrogen carrier because it can be easily liquefied with a high hydrogen storage density and emits no greenhouse gas during the dihydrogen evolution process. The ammonia oxidation reaction (AOR) in an electrochemical system has an important merit in which a very high-purity dihydrogen gas can be obtained without an additional separation process that is typically needed for thermochemical decomposition processes. Herein, the electrochemical AOR was carried out in a solid acid electrolysis cell (SAEC) at an intermediate temperature around 250 °C, in which a solid composite of CsH2PO4 mixed with SiP2O7 was used as an electrolyte and Pt/C-based electrocatalysts were employed as the electrode materials of both anode and cathode. The Pt/C electrode material was modified with the CsH2PO4/SiP2O7 electrolyte in order to enhance the electrocatalytic activity for the AOR with an improved H2 production rate. Over the SAEC system reported here, a high AOR performance was obtained with a current density of 67.1 mA/cm2 and Faradaic efficiency (FE) of 98.2%. This study can suggest the significant potential of SAEC for the carbon-free H2 production from the selective electrochemical oxidation of NH3.

The underlying mechanism trade-off between particle proximity effect and low-Pt loading for oxygen reduction and methanol oxidation reaction activity

Highly efficient and stable Pt-based electrocatalysts have broad application prospects in fuel cells, among which, Pt loading accompanied with particle size, interparticle distance (ipd), and interaction with support are identified as key contributors for high activity and selectivity. Herein, we have developed the nitrogen-doped graphite-like carbon sheets supporting low-Pt loading (Pt@N-GC) with uniform size and controllable ipd, and disentangled the main effect of ipd on oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) activity. The optimal 5.0 wt% low-Pt loading results in more abundant Pt sites and lower ipd, which leads to the higher surface reactivity by proximity effect, and 2e− pathway can be hindered by strongly resorbing and reducing H2O2 to promote 4e− pathway towards ORR. Simultaneously, the 5.0 wt% Pt@N-GC can effectively improve the MOR activity, enhance the adsorption of -OH group under the appropriate ipd, so as to promote the instantaneous oxidation of CO and enhance the tolerance, and accelerate the oxidative dehydrogenation of methanol. Benefiting by the synergistic effect of Pt nanoparticles and N-GC support, all Pt@N-GCs exhibit bifunctional electrocatalytic activity and durability. We believe the gained trade-off of the loading and proximity effect of Pt, and its influence on catalytic activity and selectivity contributes to design more promising low-Pt loading bifunctional catalysts for fuel cell.

Unique (100) Surface Configuration Enables Promising Oxygen Reduction Performance for Pt3Co Nanodendrite Catalysts.

Selective exposure of active surfaces of Pt-based electrocatalysts has been demonstrated as an effective strategy to improve Pt utilization and promote oxygen reduction reaction (ORR) activity in fuel cell application. However, challenges remain in stabilizing those active surface structures, which often suffer undesirable degradation and poor durability along with surface passivation, metal dissolution, and agglomeration of Pt-based electrocatalysts. To overcome the aforementioned obstacles, we here demonstrate the unique (100) surface configuration enabling active and stable ORR performance for bimetallic Pt3Co nanodendrite structures. Using elaborate microscopy and spectroscopy characterization, it is revealed that the Co atoms are preferentially segregated and oxidized at the Pt3Co(100) surface. In situ X-ray absorption spectroscopy (XAS) shows that such (100) surface configuration prevents the oxygen chemisorption and oxide formation on active Pt during the ORR process. Thus, the Pt3Co nanodendrite catalyst shows not only a high ORR mass activity of 730 mA/mg at 0.9 V vs RHE, which is 6.6-fold higher than that of the Pt/C, but also impressively high stability with 98% current retention after the acceleration degradation test in acid media for 5000 cycles, far exceeding the Pt or Pt3Co nanoparticles. Density functional theory (DFT) calculation also confirms the lateral and structural effects from the segregated Co and oxides on the Pt3Co(100) surface in reducing the catalyst oxophilicity and the free energy for the formation of an OH intermediate in the ORR.

Highly Stable Pt-Based Oxygen Reduction Electrocatalysts toward Practical Fuel Cells: Progress and Perspectives

The high cost and poor reliability of cathodic electrocatalysts for the oxygen reduction reaction (ORR), which requires significant amounts of expensive and scarce platinum, obstructs the broad applications of proton exchange membrane fuel cells (PEMFCs). The principles of ORR and the reasons for the poor stability of Pt-based catalysts are reviewed. Moreover, this paper discusses and categorizes the strategies for enhancing the stability of Pt-based catalysts in fuel cells. More importantly, it highlights the recent progress of Pt-based stability toward ORR, including surface-doping, intermetallic structures, 1D/2D structures, rational design of support, etc. Finally, for atomic-level in-depth information on ORR catalysts in fuel cells, potential perspectives are suggested, such as large-scale preparation, advanced interpretation techniques, and advanced simulation. This review aims to provide valuable insights into the fundamental science and technical engineering for practical Pt-based ORR electrocatalysts in fuel cells.

Direct atomic-level insight into oxygen reduction reaction on size-dependent Pt-based electrocatalysts from density functional theory calculations

Developing novel oxygen reduction reaction (ORR) catalysts with high activity is urgent for proton exchange membrane fuel cells. Herein, we investigated a group of size-dependent Pt-based catalysts as promising ORR catalysts by density functional theory calculations, ranging from single-atom, nanocluster to bulk Pt catalysts. The results showed that the ORR overpotential of these Pt-based catalysts increased when its size enlarged to the nanoparticle scale or reduced to the single-atom scale, and the Pt38 cluster had the lowest ORR overpotential (0.46 V) compared with that of Pt111 (0.57 V) and single atom Pt (0.7 V). Moreover, we established a volcano curve relationship between the ORR overpotential and binding energy of O* (ΔEO*), confirming the intermediate species anchored on Pt38 cluster with suitable binding energy located at top of volcano curve. The interaction between intermediate species and Pt-based catalysts were also investigated by the charge distribution and projected density of state and which further confirmed the results of volcano curve.

Controlled doping of carbon catalyst supports by atomic replacement via gasification-assisted heteroatom doping

Due to a set of unique properties, carbon materials are applied as supports for metal-based catalysts in a wide variety of established and emerging (electro-)catalytical transformations. By introducing heteroatoms such as N, S and P into carbon supports, metal-support interactions can be tuned, enabling an optimization of catalyst performance in terms of activity, selectivity and stability. However, the exact impact of carbon heteroatom doping on catalyst performance remains often poorly understood, as the effects are inseparable from the clustered influence of other support properties such as texture and nanostructure. In this context, we present gasification-assisted heteroatom doping (GAHD) as a novel, broadly applicable post synthesis approach to exchange carbon surface atoms against heteroatoms while retaining the properties of the parental carbon. Employing GAHD, N, S and P doping of carbons with widely varying properties could be achieved, allowing, for example, incorporation of up to 13.1 wt-% S into an activated carbon at a change of specific surface area of only 4.4%. As a proof-of-concept, comparable N, S and P doped carbon nanofiber supports were used to prepare Pt-based electrocatalysts for the oxygen reduction reaction and probe the influence of the heteroatom dopants on their stability by accelerated stress tests in different potential regimes. In this context, P and S doped supports were found to exhibit a high degree of interaction with Pt, providing increased degradation resistance compared to N and non-doped support.

Ultra-Low Pt Doping and Pt-Ni Pair Sites in Amorphous/Crystalline Interfacial Electrocatalyst Enable Efficient Alkaline Hydrogen Evolution.

Noble metal doping can achieve an increase in mass activity (MA) without sacrificing catalysis efficiency and stability, so that alkaline hydrogen evolution reaction (HER) performance of the catalyst can be optimized to the maximum degree. However, its excessively large ionic radius makes it difficult to achieve either interstitial doping or substitutional doping under mild conditions. Herein, a hierarchical nanostructured electrocatalyst with enriched amorphous/crystalline interfaces for high-efficiency alkaline HER is reported, which is composed of amorphous/crystalline (Co, Ni)11 (HPO3 )8 (OH)6 homogeneous hierarchical structure with an ultra-low doped Pt (Pt-a/c-NiHPi). Benefiting from the structural flexibility of the amorphous component, extremely low Pt (0.21wt.%, totally 3.31µg Pt on 1 cm-2 NF) are stably doped on it via a simple two-phase hydrothermal method. The DFT calculations show that due to the strongly electron transfer between the crystalline/amorphous components at the interfaces, electrons finally concentrate toward Pt and Ni in the amorphous components, thus the electrocatalyst has near-optimal energy barriers and adsorption energy for H2 O* and H* . With the above benefits, the obtained catalyst exhibits an exceptionally high MA (39.1mA µg-1 Pt ) at 70mV, which is almost the highest level among the reported Pt-based electrocatalysts for alkaline HER.

Investigation of the Synergistic Effect in Polypyrrole/Ni-Doped NASICON Composites for an Enhanced Hydrogen Evolution Reaction

Electrocatalysts with a synergistic combination of low-cost, eco-friendly, and highly electrochemical active properties are frequently used in hydrogen evolution reactions (HERs) without utilizing any noble or toxic metals. Herein, a simple chemical oxidative polymerization method has been used to synthesize a set of nanocomposites of polypyrrole (PPy) and Ni-doped NASICON-structured Na3NixFe(2–x)(PO4)(SO4)2 [NFPS(Nix)], which shows remarkable HER activity. Among them, as-synthesized uniform spherical-shaped PPy/NFPS(Ni0.5) (optimized ratio) was found to show the lowest onset overpotential, −13 mV versus reversible hydrogen electrode (RHE), with a lesser Tafel slope of 58 mV dec–1, which is comparable to Pt/C and superior among the majority of the polymer-based HER catalysts. Also, it offers a current density of 10 mA/cm2 at a noticeably lower overpotential of −111 mV versus RHE. Moreover, the nanocomposite also exhibits notable long-sustaining environmental and catalytic stability along with exceptional durability. In PPy/NFPS(Ni0.5), improved electrocatalytic activity comes from the synergistic effect of the NFPS(Ni0.5) and PPy matrix, which results in enormous electrocatalytically active sites and facilitates easy charge transportation. Thus, real-world hydrogen production may hold possibilities for the as-synthesized PPy/NFPS(Ni0.5) nanocomposite as well as an alternative to a Pt-based electrocatalyst for the HER.

Pt-Quantum-Dot-Modified Sulfur-Doped NiFe Layered Double Hydroxide for High-Current-Density Alkaline Water Splitting at Industrial Temperature.

Suitable electrocatalysts for industrial water splitting can veritably promote practical hydrogen applications. Rational surface design is exceptionally significant for electrocatalysts to bridge the gap between fundamental science and industrial expectation in water splitting. Here, Pt-quantum-dot-modified sulfur-doped NiFe layered double hydroxides (Pt@S-NiFe LDHs) are designed with eximious catalytic activity toward hydrogen evolution reaction (HER) under industrialcondition. Benefiting from enhanced binding energy, mass transfer, and hydrogen release, Pt@S-NiFe LDHs exhibit outstanding activity in HER at high current densities. Notably, it obtains an impressively low overpotential of 71mV and long-term stability of 200 h at 100 mA cm-2 , exceeding commercial 40% Pt/C and most reported Pt-based electrocatalysts. Its mass activity is 2.7 times higher than that of 40% Pt/C with an overpotential of 100 mV. Furthermore, at industrial temperature (65°C), the electrolyzer based on Pt@S-NiFe LDH needs just 1.62 V to reach the current density of 100mA cm-2 , superior to that of the commercial one of 40% Pt/C//IrO2 . This work provides rational ideas to develop electrocatalysts with exceptional performance for industrial high-temperature water splitting at high current densities.

Phosphoric acid resistance PtCu/C oxygen reduction reaction electrocatalyst for HT-PEMFCs: A theoretical and experimental study

In high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs), dissociative H3PO4 in cathode will block the active sites of Pt-based electrocatalyst, which thus failure to catalyze the oxygen reduction reaction (ORR). Therefore, the electrocatalysts for the ORR in HT-PEMFCs with high resistance to H3PO4 poisoning are significantly important. Due to the similar bonding structure between HxPO43-x/O2 and Pt (Pt-O), the design of catalysts which could selectively reduce the adsorption energy of the H3PO4 is urgently needed. In this work, we screen proper H3PO4 resistance electrocatalysts through theoretical calculation based on the adsorption energy difference between HxPO43-x and O2 as an evaluation criterion. Then, we prepared a series of PtxCu catalysts based on the theoretical calculation results and further studied the structure-performance relationship of phosphoric acid-resistant catalysts through combining physical property characterization and electrochemical tests including half-cell and single-cell. The mass activity of Pt2Cu/C is 0.51 A/mgPt, exceeding the DOE's 2020 target of 0.44 A/mgPt. After add 0.1 M H3PO4 into the HClO4 electrolyte, the half-wave potential (E1/2) of Pt2Cu/C is only negatively shifted by 47 mV, much lower than 90 mV of TKK Pt/C. Furthermore, the HT-PEMFC with Pt2Cu/C in the cathode shows a peak power density of 383.4 mW/cm2, which surpasses that of TKK Pt/C for 231.0 mW/cm2. Our strategy of screening catalysts based on the adsorption energy difference study and further verified by experimental methods provides a promising strategy for the design of practical electrocatalyst in the cathode of HT-PEMFCs.

Kinetics of Oxygen Reduction Reaction of Polymer-Coated MWCNT-Supported Pt-Based Electrocatalysts for High-Temperature PEM Fuel Cell

Sluggish oxygen reduction reaction (ORR) of electrodes is one of the main challenges in fuel cell systems. This study explored the kinetics of the ORR reaction mechanism, which enables us to understand clearly the electrochemical activity of the electrode. In this research, electrocatalysts were synthesized from platinum (Pt) catalyst with multi-walled carbon nanotubes (MWCNTs) coated by three polymers (polybenzimidazole (PBI), sulfonated tetrafluoroethylene (Nafion), and polytetrafluoroethylene (PTFE)) as the supporting materials by the polyol method while hexachloroplatinic acid (H2PtCl6) was used as a catalyst precursor. The oxygen reduction current of the synthesized electrocatalysts increased that endorsed by linear sweep voltammetry (LSV) curves while increasing the rotation rates of the disk electrode. Additionally, MWCNT-PBI-Pt was attributed to the maximum oxygen reduction current densities at −1.45 mA/cm2 while the minimum oxygen reduction current densities of MWCNT-Pt were obtained at −0.96 mAcm2. However, the ring current densities increased steadily from potential 0.6 V to 0.0 V due to their encounter with the hydrogen peroxide species generated by the oxygen reduction reactions. The kinetic limiting current densities (JK) increased gradually with the applied potential from 1.0 V to 0.0 V. It recommends that the ORR consists of a single step that refers to the first-order reaction. In addition, modified MWCNT-supported Pt electrocatalysts exhibited high electrochemically active surface areas (ECSA) at 24.31 m2/g of MWCNT-PBI-Pt, 22.48 m2/g of MWCNT-Nafion-Pt, and 20.85 m2/g of MWCNT-PTFE-Pt, compared to pristine MWCNT-Pt (17.66 m2/g). Therefore, it can be concluded that the additional ionomer phase conducting the ionic species to oxygen reduction in the catalyst layer could be favorable for the ORR reaction.

Ternary PtZrNi nanorods for efficient multifunctional electrocatalysis towards oxygen reduction and alcohol oxidation

Pt-based alloys with precise structure and composition design have been considered to be effective and robust novel electrocatalysts for fuel cells. Whereas, the sluggish kinetics of oxygen reduction reaction (ORR) and low intrinsic activity of Pt limited their real application on a large scale. Herein, a novel ternary PtZrNi nanorods (PtZrNi NRs) was synthesized via a facile wet-chemical method to achieve high electrocatalytic performance for both ORR and alcohol oxidation reaction owing to the synergism of chosen three elements and prominent one-dimensional morphology. Specifically, the PtZrNi NRs show enhanced mass and specific activities of 0.755 A mgPt-1 and of 0.97 mA/cm2 at 0.9 VRHE towards ORR in acidic media, which are 4.7 and 4.4 times of those of commercial Pt/C, respectively. Additionally, in alkaline media, the PtZrNi NRs also exhibit superior ORR mass and specific activities of 3.216 A mgPt-1and 4.13 mA/cm2, enhanced by 34.6 and 31.3 times compared with those of commercial Pt/C, respectively. The PtZrNi NRs retain the nanorod shape well without agglomeration after an accelerated durability test (20000 cycles). This work may offer a new perspective for engineering high-performance Pt-based electrocatalysts for commercial fuel cells.

The integrated study of the morphology and the electrochemical behavior of Pt-based ORR electrocatalysts during the stress testing

This article provides relevant information on the catalysts’ morphological characteristics that allow for the optimal combination of activity and durability of the materials for proton-exchange membrane fuel cells. The home-made Pt/C and PtCu/C catalysts have been established to have at least by 20% higher values of the mass activity in the oxygen reduction reaction than the commercial Pt/C analogue (HiSPEC 3000, Johnson Matthey). The detailed analysis of the microstructure by transmission electron microscopy and the electrochemical parameters by electrochemical surface-sensitive methods after the stress testing has allowed estimating the contribution of various mechanisms to the degradation process. After the stress testing, the residual activity in the oxygen reduction reaction of the home-made materials has proved to be at least more than double that of the commercial Pt/C catalyst. A specific feature of this work is the presented correlation between the morphology and the electrochemical behavior of the catalysts, with this interconnection appearing to be a valuable resource for a wide range of scientists.