Pt-alloy (Pt–M) nanoparticles (NPs) with less-expensive 3d transition metals (M = Ni, Cu, Co) supported on high-surface-area carbon supports are currently the state-of-the-art (SoA) solution to reach the production phase in proton exchange membrane fuel cells (PEMFCs). However, while Pt–M electrocatalysts show promise in terms of increased activity for oxygen reduction reaction (ORR) and, thus, cost reductions from the significantly lower use of expensive and rare Pt, key challenges in terms of synthesis, activation, and stability remain to unlock their true potential. This work systematically tackles them with a combination of electrocatalyst synthesis and characterization methodologies including thin-film rotating disc electrodes (TF-RDEs), an electrochemical flow cell linked to an inductively coupled plasma mass spectrometer (EFC-ICP-MS), and testing in 50 cm 2 membrane electrode assemblies (MEAs). In the first part of the present work, we highlight the crucial importance of the chemical activation (dealloying) step on the performance of Pt–M electrocatalysts in the MEA at high current densities (HCDs). In addition, we provide the scientific community with a preliminary and facile method of distinguishing between a “poorly” and “adequately” dealloyed (activated) Pt-alloy electrocatalyst using a much simpler and affordable TF-RDE methodology using the well-known CO-stripping process. Since the transition-metal cations can also be introduced in a PEMFC due to the degradation of the Pt–M NPs, the second part of the work focuses on presenting clear evidence on the direct impact of the lower voltage limit (LVL) on the stability of Pt–M electrocatalysts. The data suggests that in addition to intrinsic improvements in stability, significant improvements in the PEMFC lifetime can also be obtained via the correct MEA design and applied limits of operation, namely, restricting not just the upper but equally important also the lower operation voltage.

The proton exchange membrane fuel cell performance of carbon-supported Pt, PtRu, and PtMo catalysts on reformate gas mixtures was investigated. The catalysts were tested as low Pt loaded electrodes in membrane electrode assemblies at 80°C using H 2 ; 10, 40, 100 ppm CO in H 2 ; 25% CO 2 in H 2 , and 40 ppm CO/25% CO 2 in H 2 reformate gas mixtures as the fuel stream. The PtMo catalyst showed better CO tolerance than the PtRu catalyst at 100 ppm, but showed poorer CO 2 tolerance to both Pt and PtRu. With 40 ppm CO/25% CO 2 in H 2 , PtMo showed inferior overall reformate tolerance to PtRu.The effective operation of proton exchange membrane fuel cells ͑PEMFCs͒ with impure H 2 , produced by the reforming of hydrocarbons or oxygenated hydrocarbons, depends on the use of anode electrocatalysts that are tolerant to the major contaminants in the resulting reformate ͑i.e., CO and CO 2 ͒. Even low levels of CO have a severe poisoning effect on the performance of Pt anodes. 1 Recently, it has been found that CO 2 also has a modest poisoning effect on Pt. 2,3 Currently, the use of carbon-supported PtRu bimetallic catalysts provides some tolerance to low levels of CO and reasonable concentrations of CO 2 . However, at higher levels of CO (Ͼ10 ppm), the tolerance of PtRu catalysts is not sufficient when used at economic electrode Pt loadings (Ͻ0.25 mg ͑Pt͒ cm Ϫ2 geometric). Practical reformate tolerance is currently achieved by the introduction of an air bleed to the fuel stream to remove the residual CO by selective oxidation within the anode. 4 A more elegant solution to reformate tolerance is the development of anode catalysts capable of operating effectively without loss in overpotential on reformate. Many Pt-based catalysts have been investigated for their resistance to poisoning toward CO. 5 The most promising systems are based on the addition of Mo and W to Pt, which can show greater CO tolerance than PtRu catalysts. Niedrach and Weinstock first showed the promotional effect of Mo and W oxides on the H 2 oxidation activity of Pt with CO/H 2 fuel mixtures, in 1965. 1 More recently, carbon-supported PtMo, PtW, PtCoMo, and PtCoW catalysts have all shown enhanced CO tolerance properties when compared to carbon-supported PtRu catalysts. 6-8 In particular, one recent report showed that a carbon-supported PtMo catalyst with a Pt:Mo ratio of 4:1 showed only a ca. 50 mV loss in cell voltage on 100 ppm CO in H 2 , compared to pure H 2 , when tested in a small PEMFC single cell at 85°C. In contrast, a carbon-supported PtRu catalyst (Pt:Ru ϭ 1:1) showed a ca. 160 mV loss. 9 Although the vast majority of reformate tolerance work has concentrated on the strongly poisoning effects of trace concentrations of CO, few reports have discussed the effect of the major impurity ͑in terms of concentration͒ of reformate, CO 2 . In particular, there have been no reports of operation of PtMo anodes on fuel mixtures that contain CO 2 . This paper reports the performance of a carbonsupported PtMo anode catalyst, together with standard Pt and PtRu c...

Pt-alloy (Pt-M) nanoparticles (NPs) with less expensive 3d transition metals (M = Ni, Cu, Co) supported on high surface area carbon supports, are currently the state-of-the-art (SoA) solution to reach the production phase in proton exchange membrane fuel cells (PEMFCs).1 However, while Pt-M electrocatalysts show promise in terms of increased activity for oxygen reduction reaction (ORR) and thus, cost reductions related with a significantly lower use of expensive and rare Pt, many key challenges remain at unlocking their true potential.This work systematically tackles several of these key challenges with a combination of electrocatalysts synthesis and characterization methodologies, namely thin-film rotating disc electrode (TF-RDE), electrochemical flow cell coupled to inductively coupled plasma mass spectrometer (EFC-ICP-MS) as well as the membrane electrode assembly (MEA). For instance, intermetallics as a sub-class of Pt-M electrocatalysts, holds promise at improving their intrinsic stability, however, usually at the sacrifice of the electrochemically active surface area (ECSA). In relation to this, we show a production pathway based on the proprietary double passivation with galvanic displacement (GD) method 2,3 as an intrinsically better methodology for deposition of Pt NPs, combining both the intermetallic structure and very high ECSA in the same electrocatalyst material. This is possible due to the intrinsically better mechanism of Pt NP deposition on carbon substrates. Whereas Pt NP synthesis and deposition is sequential in nature (2. step process) when using conventional deposition methods, in the case of double passivation with GD method Pt NPs crystallize directly out of the carbon support and combining these two crucial steps into a single one (Scheme 1). Secondly, we highlight the decisive importance of the chemical activation (de-alloying) step on the performance of Pt-M electrocatalysts in the MEA, namely at high current densities (HCDs). In addition, we provide the scientific community the necessary tools to properly evaluate their suitability of de-alloyed (chemically activated) Pt-M electrocatalysts using a much simpler and affordable TF-RDE methodology by using the well-known CO-electrooxidation. References: L. J. Moriau et al., iScience, 102102 (2021).M. Gatalo et al., Angew. Chemie, 131, 13400–13404 (2019).M. Gatalo, N. Hodnik, M. Gaberšček, and M. Bele, PCT/EP2020/057334 (2020). Figure 1

This study aimed to investigate nutritional status, body composition, dietary protein intake, handgrip strength, 6 min or 4 m walk tests, self-reported physical activity, physical function, and quality of life (QoL-EORTC-QLQc30) at commencement of chemotherapy; to detect changes over time (from commencement of chemotherapy, and after 3, 6, 12, 26 and 52 weeks) in women with metastatic breast cancer (MBC); and to investigate the relationship between nutritional variables. ‘Sarcopenia’ was defined as low muscle mass and strength, ‘myosteatosis’ as muscle fat-infiltration (CT scan). Continuous variables were analysed using paired t-tests between baseline and follow-ups. Fifteen women (54y, 95% CI [46.3;61.2]) were recruited. At baseline, malnutrition was present in 3 (20%) participants, sarcopenia in 3 (20%) and myosteatosis in 7 (54%). Thirteen (87%) participants had low protein intake; low handgrip strength was observed in 0, and low walk test distance and physical activity in four (27%) participants. Physical function and QoL were low in 10 (67%) and 9 (60%), respectively. QoL between baseline and 52 weeks decreased by 11.7 (95% CI [2.4;20.9], p = 0.025). Other variables did not significantly change over time. In this small study sample, myosteatosis, low dietary protein intake, low exercise levels and impaired quality of life and physical function are common.