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The excellent physical and chemical properties of palladium(Pd) have made its application and demand increase gradually. Therefore, it is important to develop a new material to efficiently separate and purify palladium from secondary sources to ensure its supply. In this work, a thermosensitive palladium smart imprinted polymer(Pd-T-SIP) was synthesized, which could achieve the efficient separation and purification of Pd. The microstructure and morphology of Pd-T-SIP were characterized. The experimental results showed that the Pd-T-SIP showed the maximum adsorption amount(Q) of 0.1022 mmol/g for Pd(IV), the desorption rate(D) was 83.09%, and it had good reusability. Theoretical studies showed that the adsorption process of Pd-T-SIP was suitable to be described by quasi-first-order model and Langmuir model, which indicated that the adsorption of Pd-T-SIP was monolayer adsorption. Finally, Pd-T-SIP was applied to the platinum group catalyst leach solution, and it could be found that its adsorption/desorption effect was more excellent, with its adsorption amount reaching 0.1558 mmol/L, desorption rate reaching 77.14%, and the palladium purity after one adsorption/desorption cycle increased from 13.75% to 30.62%, and the purity of platinum group metals increased from 40.29% to 73.56% after one adsorption/desorption cycle. [ABSTRACT FROM AUTHOR]

Automotive catalysts containing Platinum Group Metals (PGMs) are valuable secondary raw materials for refineries. Hydrometallurgical processing of catalysts is ineffective due to the low PGMs content—0.15–0.3%. Therefore, such raw materials are melted into an iron collector containing 1.5–5% PGMs. However, when leaching a collector containing 10–20% Si in both HCl and H2SO4, the recovery of PGMs does not exceed 40%. The latter indicates incomplete destroying of the PGM-encapsulating ferrosilicon matrix. To completely destroy the ferrosilicon matrix, it is proposed to carry out the leaching process in a mixture of HCl and HF. In this case, the extraction of Fe into solution and Si into the gas phase (in the form of SiF4) exceeds 90%. This should be sufficient to completely destroy the ferrosilicon matrix and release PGMs. The current work presents the results of studies of the leaching kinetics of the iron collector containing ferrosilicon in a mixture of HCl and HF using the Shrinking Core Model (SCM). It was found that the greatest positive effect on Fe extraction into solution is exerted by HCl concentration and temperature, while Si release into the gas phase is only influenced by HF concentration. In addition, during the destroying of ferrosilicon, FeF2 is formed and deposited on the surface of the material in the form of thin-film conglomerates. This leads to diffusion difficulties and a gradual decrease in the intensity of the iron collector leaching 30 min after the start of process. After 120 min, there may be a decrease in Fe recovery into solution. [ABSTRACT FROM AUTHOR]

Recovering platinum group precious metals (PGMs) from used industrial catalysts is crucial and challenging. This study delves into an environmentally friendly approach to selectively recover PGMs from commercial air purifiers using photocatalytic redox technology. We harness sunlight as the energy source to activate the photocatalysts, facilitating the complete dissolution of precious metals under natural light irradiation. [Display omitted] The mitigation of environmental and energy crises could be advanced by reclaiming platinum group precious metals (PGMs) from decommissioned air purification catalysts. However, the complexity of catalyst composition and the high chemical inertness of PGMs significantly impede this process. Consequently, recovering PGMs from used industrial catalysts is crucial and challenging. This study delves into an environmentally friendly approach to selectively recover PGMs from commercial air purifiers using photocatalytic redox technology. Our investigation focuses on devising a comprehensive strategy for treating three-way catalysts employed in automotive exhaust treatment. By meticulously pretreating and modifying reaction conditions, we achieved noteworthy results, completely dissolving and separating rhodium (Rh), palladium (Pd), and platinum (Pt) within a 12-h time frame. Importantly, the solubility selectivity persists despite the remarkably similar physicochemical properties of Rh, Pd, and Pt. To bolster the environmental sustainability of our method, we harness sunlight as the energy source to activate the photocatalysts, facilitating the complete dissolution of precious metals under natural light irradiation. This eco-friendly recovery approach demonstrated on commercial air purifiers, exhibits promise for broader application to a diverse range of deactivated air purification catalysts, potentially enabling implementation on a large scale. [ABSTRACT FROM AUTHOR]

Anion‐exchange membrane fuel cells provide the possibility to use platinum group metal‐free catalysts, but the anodic hydrogen oxidation reaction (HOR) suffers from sluggish kinetics and its source is still debated. Here, over nickel‐tungsten (Ni−W) alloy catalysts, we show that the Ni : W ratio greatly governs the HOR performance in alkaline electrolyte. Experimental and theoretical studies unravel that alloying with W can tune the unpaired electrons in Ni, tailoring the potential of zero charge and the catalytic surface to favor hydroxyl adsorption (OHad). The OHad species coordinately interact with potassium (K+) ions, which break the K+ solvation sheath to leave free water molecules, yielding an improved connectivity of hydrogen‐bond networks. Consequently, the optimal Ni17W3 alloy exhibits alkaline HOR activity superior to the state‐of‐the‐art platinum on carbon (Pt/C) catalyst and operates steadily with negligible decay after 10,000 cycles. Our findings offer new understandings of alloyed HOR catalysts and will guide rational design of next‐generation catalysts for fuel cells. [ABSTRACT FROM AUTHOR]

Metal-catalyzed highly Markovnikov-type selective hydrofunctionalization of terminal alkynes provides a straightforward and atom-economical route to access 1,1-disubstituted alkenes, which have a wide range of applications in organic synthesis. However, the highly Markovnikov-type selective transformations are challenging due to the electronic and steric effects during the addition process. With the development of metal-catalyzed organic synthesis, different metal catalysts have been developed to solve this challenge, especially for platinum group metal catalysts. In this perspective, we review homogeneous metal-catalyzed Markovnikov-type selective hydrofunctionalization of terminal alkynes according to the classified element types as well as reaction mechanisms. Future avenues for investigation are also presented to help expand this exciting field. [ABSTRACT FROM AUTHOR]

Platinum group catalysts are still the most effective catalysts for oxygen reduction reaction (ORR) of proton exchange membrane fuel cells. Thus, the high cost and susceptibility to deactivation during working process are becoming more and more prominent with the proceeding of the application. To meet the requirements of enhancing reaction kinetics and decreasing the cost of Pt-based catalysts, we design a N -doped hollow carbon nanorods (HCNR) supported platinum-nickel based catalyst for ORR. Compared with the benchmark commercial Pt/C catalyst, the HCNR supported PtNi catalysts (PtNi/HCNR) show excellent catalytic activity for ORR and long-time running durability. The onset potential (E 0) and half wave potential (E 1/2) of medium platinum content catalyst (PtNi/HCNR-2) catalyzed ORR are 1.02 V and 0.914 V, separately, which surpass than that of the 20 wt% Pt/C catalyst. Furthermore, PtNi/HCNR-2 catalyzed ORR has a lower Tafel slope (92.05 mV dec−1), faster electron transfer rate, lower H 2 O 2 yield rate and better stability. The synergistic effect between N -doped HCNR and PtNi alloy assures the high performance for ORR. HCNR improves the electrical conductivity, while the doped nitrogen provides "coordination nests" for PtNi catalyst, which provide more catalytic active sites for ORR. PtNi/HNCR-based catalysts have great potential to be low-cost, high performance catalysts for ORR. [Display omitted] • N -doped hollow carbon nanorods support for catalysts were synthesized. • HCNR supported PtNi catalysts show 20 mV higher onset potential for ORR than Pt/C. • Doping with nitrogen enhanced the affinity between HCNR and PtNi catalyst. • Hollow structure facilitates the transport of oxygen and electrons for ORR. [ABSTRACT FROM AUTHOR]

Atomically dispersed catalysts are a promising alternative to platinum group metal catalysts for catalyzing the oxygen reduction reaction (ORR), while limited durability during the electrocatalytic process severely restricts their practical application. Here, we report an atomically dispersed Co-doped carbon−nitrogen bilayer catalyst with unique dual-axial Co–C bonds (denoted as Co/DACN) by a smart phenyl-carbon-induced strategy, realizing highly efficient electrocatalytic ORR in both alkaline and acidic media. The corresponding half-wave potential for ORR is up to 0.85 and 0.77 V (vs. reversible hydrogen electrode (RHE)) in 0.5 M H2SO4 and 0.1 M KOH, respectively, representing the best ORR activity among all non-noble metal catalysts reported to date. Impressively, the Zn–air battery (ZAB) equipped with Co/DACN cathode achieves outstanding durability after 1,688 h operation at 10 mA cm−2 with a high current density (154.2 mA cm−2) and a peak power density (210.1 mW cm−2). Density functional theory calculations reveal that the unique dual-axial cross-linking Co−C bonds of Co/DACN significantly enhance the stability during ORR and also facilitate the 4e− ORR pathway by forming a joint electron pool due to the improved interlayer electron mobility. We believe that axial engineering opens a broad avenue to develop high-performance heterogeneous electrocatalysts for advanced energy conversion and storage. [ABSTRACT FROM AUTHOR]

The article evaluates the potential of hydrogen as a clean energy source, discussing its applications in transportation, industry and residential heating, as well as its role in achieving net zero emissions targets. It highlights ongoing efforts to produce green hydrogen and overcome technical and logistical challenges in scaling up its production and integration into existing energy systems.

The widespread application of fuel cells is hampered by the sluggish kinetics of the oxygen reduction reaction (ORR), which traditionally necessitates the use of high-cost platinum group metal catalysts. The indispensability of these metal catalysts stems from their ability to overcome kinetic barriers, but their high cost and scarcity necessitate alternative strategies. In this context, porous organic polymers (POPs), which are built up from the molecular level, are emerging as promising precursors to produce carbonaceous catalysts owning to their cost-effectiveness, high electrical conductivity, abundant active sites and extensive surface area accessibility. To enhance the intrinsic ORR activity and optimize the performance of these electrocatalysts, recognizing, designing, and increasing the density of active sites are identified as three crucial steps. These steps, which form the core of our review, serve to elucidate the link between the material structure design and ORR performance evaluation, thereby providing valuable insights for ongoing research in the field. Leveraging the precision of polymer skeletons based on molecular units, POP-derived carbonaceous catalysts provide an excellent platform for in-depth exploration of the role and working mechanism for the specific active site during the ORR process. In this review, the recent advances pertaining to the synthesis techniques and electrochemical functions of various types of active sites, pinpointed from POPs, are systematically summarized, including heteroatoms, surficial substituents and edge/defects. Notably, the structure–property relationship, between these active sites and ORR performance, are discussed and emphasized, which creates guidelines to shed light on the design of high-performance ORR electrocatalysts. [ABSTRACT FROM AUTHOR]

Platinum group metal‐free catalysts have been considered the most promising alternative for platinum‐based catalysts for the oxygen reduction reaction in fuel cells. Despite the significant advancement made in activity, their viability as fuel cell catalysts is still questionable due to their low durability. So far, deciphering the degradation mechanisms of this class of catalysts has been hampered by their undefined structure. Herein, we used a molecular model catalyst, iron‐phthalocyanine, featuring Fe−N4 active sites with resemblance to those in the more active Fe−N−C catalysts, and studied their degradation mechanisms. Based on X‐ray photoelectron spectroscopy and the electrochemical measurements, three main demetallation processes were identified: at potentials higher than 0.65 V vs. RHE, where the metal center is Fe3+, an electrochemical oxidation of the ligand ring is occurring, between 0.6 and 0.2 V vs. RHE, Fenton reagents are produced and attack the catalyst and support, and at lower voltages, where peroxide is produced by the catalyst and the carbon support. The combination of the different iron oxidation states together with the oxygen species directs to different degradation mechanisms. The decay rates obtained in the stability measurements establish what is mainly causing the loss of activity. Thereby, this model molecule can aid in understanding the degradation mechanisms of other platinum group metal‐free oxygen reduction reaction catalysts. [ABSTRACT FROM AUTHOR]

In this study, a simple photocuring method is proposed for preparing PDMS elastomers using a homogenous poly(dimethylsiloxane) (PDMS) solution in tert‐butyl acrylate (tBA) as an alternative way of mechanically blending two kinds of PDMS respectively containing vinyl and hydridosilyl groups over a platinum catalyst. Poly(dimethylsiloxane‐co‐methylvinylsiloxane) (PDMSc) with 30 mol% of vinyl moieties is synthesized. The functionalized PDMS is estimated to be soluble in tBA from theoretical calculations of solubility parameters of PDMS and several liquid monomers. The PDMS solution is satisfactorily photocured under a conventional photoinitiator. Initial modulus and strain of the photocured films increase from 144 to 552 MPa and decrease from 3.96 to 1.84, respectively, as the tBA content rises from 5 to 30 wt%. They are extremely transparent in a visible region (T > 94%) regardless of the amount of tBA. The unreacted vinyl groups in PDMSc are inter‐ or intrareacted near 200 °C and γ‐hydrogen transfer reactions from the tert‐butyl groups in poly(tert‐butyl acrylate) occur over 250 °C. One of the photocrosslinked films exhibits outstanding performance as an electroactive polymer in application. In essence, this study will initiate a new methodological research into provision of PDMS elastomers using an easily formulated photocrosslinkable PDMS solution. [ABSTRACT FROM AUTHOR]

This paper describes a detailed catalyst configuration study for a catalytic flow reversal reactor for lean methane combustion using computational modelling. The design is based on the use of a platinum group metals catalyst in the form of a washcoated monolith. A small-scale pilot plant reactor is used as the basis for the study. The computational model is based on the fundamental conservation equations of mass and energy that are solved using the finite element method with commercial software. Extensive model validation is performed using experimental data previously obtained on the pilot plant system. It is found that catalyst activity and length of the reaction section play key roles in the stable operation and performance of the system. For methane feed concentrations above about 0.5% by volume, the catalyst activity plays a relatively small role. For concentrations down to about 0.2% both the catalyst activity and reactor length become increasingly important. The complete transient history of the reactor also plays an important role in determining whether or not a stable stationary state can be achieved for a given set of inlet conditions. Computational modelling is shown to be an extremely valuable tool for the design of the reactor system. [Display omitted] • Catalyst configuration in reverse flow reactor for methane combustion is studied. • Stable operation is achieved at low catalyst activity with higher concentration. • Stable operation at low concentration requires higher catalyst activity. • The length of the catalyst section affects the performance significantly. • System history determines stable operating points. [ABSTRACT FROM AUTHOR]

Two electron oxygen reduction reaction to produce hydrogen peroxide (H 2 O 2) is a promising alternative technique to the multistep and high energy consumption anthraquinone process. Herein, Ni–Fe layered double hydroxide (NiFe-LDH) has been firstly demonstrated as an efficient bifunctional catalyst to prepare H 2 O 2 by electrochemical oxygen reduction (2e− ORR) and oxygen evolution reaction (OER). Significantly, the NiFe-LDH catalyst possesses a high faraday efficiency of 88.75% for H 2 O 2 preparation in alkaline media. Moreover, the NiFe-LDH catalyst exhibits excellent OER electrocatalytic property with small overpotential of 210 mV at 10 mA cm−2 and high stability in 1 M KOH solution. On this basis, a new reactor has been designed to electrolyze oxygen and generate hydrogen peroxide. Under the ultra-low cell voltage of 1 V, the H 2 O 2 yield reaches to 47.62 mmol g cat −1 h−1. In order to evaluate the application potential of the bifunctional NiFe-LDH catalyst for H 2 O 2 preparation, a 1.5 V dry battery has been used as the power supply, and the output of H 2 O 2 reaches to 83.90 mmol g cat −1 h−1. The excellent electrocatalytic properties of 2e− ORR and OER make NiFe-LDH a promising bifunctional electrocatalyst for future commercialization. Moreover, the well-designed 2e− ORR-OER reactor provides a new strategy for portable production of H 2 O 2. [Display omitted] • Design of bifunctional NiFe-LDH catalyst for 2e− ORR and OER for the first time. • Development of portable hydrogen peroxide reactor based on the bifunctional catalyst. • Non-noble metal-based bifunctional catalyst replaces platinum group metal as anode. • Overpotential of 210 mV at 10 mA cm−2 for OER and 80% selectivity for 2e− ORR of NiFe-LDH catalyst. [ABSTRACT FROM AUTHOR]

Platinum on carbon (Pt/C) catalyst is commercially adopted in fuel cells but it undergoes formidable active‐site poisoning by carbon monoxide (CO). In particular, given the sluggish kinetics of hydrogen oxidation reaction (HOR) in anion‐exchange membrane fuel cell (AEMFC), the issues of Pt poisoning and slow rate would combine mutually, notably worsening the device performances. Here we overcome these challenges through incorporating cobalt (Co) into molybdenum‐nickel alloy (MoNi4), termed Co‐MoNi4, which not only shows superior HOR activity over the Pt/C catalyst in alkali, but more intriguingly exhibits excellent CO tolerance with only small activity decay after 10 000 cycles in the presence of 500 parts per million (ppm) CO. When feeding with CO (250 ppm)/H2, the AEMFC assembled by this catalyst yields a peak power density of 394 mW cm−2, far exceeding the Pt/C catalyst. Experimental and computational studies reveal that weakened CO chemisorption originates from the electron‐deficient Ni sites after Co incorporation that suppresses d→CO 2π* back‐donation. [ABSTRACT FROM AUTHOR]

Fuel cells are already employed in commercial transportation even though their price is still too high to enable widespread production. A viable and promising pathway taken to lower this price is the replacement of expensive constitutes, namely the platinum-based catalysts at the cathode, by platinum group metal-free catalysts based on abundant materials, such as iron. This led to the development of iron-based catalysts that show high activity towards the oxygen reduction reaction. The extraction of the intrinsic catalytic activity of any catalyst is important both for finding relations between the chemical properties of the active sites and their activity, as well as a comparison measure between catalysts. An important parameter that has been elusive for many years is the turnover frequency, which is derived form the number of electrochemical active sites' density (EASD). The ability to measure the EASD was very limited until the past few years, and several methods have been proposed to measure it. It is important for the investigation of catalysts' stability and the development of durable catalysts. This review aims to critically analyze the current methodologies used for the quantification and analysis of the active sites. [ABSTRACT FROM AUTHOR]

The initial coal fly ash zeolites (CFAZ) are obtained from raw coal fly ash with two SiO2/Al2O3 ratios of 2.0 and 2.2 by hydrothermal activation or by two‐stage process. Microwave plasma surface treatment of CFAZ is performed to modify their surface and therefore their catalytic activity in total VOC oxidation. CHF3 and SF6 are used as plasma agents at two different treatments times—30 s and 60 s. The obtained hierarchal CFAZ are characterized by X‐ray diffraction, N2‐physisorption, temperature programmed reduction experiments, UV–vis spectroscopy and X‐ray photoelectron spectroscopy to clarify the effect of plasma treatment on the surface and reduction properties, morphology and structure of the modified samples. The catalytic performance of the modified CFAZ is investigated in a flow system toward toluene oxidation in the temperature range of 250–520 °C. It has been observed that CHF3 favors the catalytic activity of CFAZ at shorter treatment duration, while SF6 inhibits their catalytic properties. The development of efficient low‐cost catalyst will contribute to the saving of critical raw materials such as platinum group metals, and to the utilization of the enormous resource of coal ash instead of its landfilling in accordance to the development of circular economy and smart waste management. [ABSTRACT FROM AUTHOR]

Three events occurred in the second half of 1946 in three adjoining US States (NJ, NY, and PA) which marked the birth of Hydrosilylation Technology. They occurred before the landmark 1957 JACS paper and the 1958 issued US patent by Speier et al. and before Chalk and Harrod named the reaction. First, on 27 June 1946, Mackenzie et al., of Montclair Research Corp., applied for a patent to prepare addition compounds of hydridosilanes and unsaturated organic compounds. Then, on 9 October 1946, Wagner and Strother of Union Carbide Corp. applied for a patent on a process to produce organic compounds of silicon with Si–C bonds by reacting a hydridosilane and an alkene or alkyne in the presence of a catalyst metal of the platinum group. Finally, Sommer et al., submitted a paper on peroxide-catalyzed hydrosilylation to JACS on 17 December 1946. It was published in January 1947. The landmark patent interference § and priority § case law associated with the Mackenzie et al. and Wagner et al., applications is well known to patent attorneys. This presentation will retrace the origins of hydrosilylation and report events (1946–1960) in the history of the reaction that are most probably unknown to most authors and presenters of hydrosilylation investigations. George Wagner's contribution to the birth of this technology is also highlighted. [ABSTRACT FROM AUTHOR]

Developing non-noble metal oxides, replacing platinum group catalysts for auto-exhaust purification, where their usage amount exceeds 40 % of global demand, remains a challenge. Herein, we presented a combined approach on the synthesis and application of robust CuO x /TiO 2 catalysts with ultra-fine CuO x clusters (ca. 1 nm). The strong interaction between CuO x and TiO x induces favorable interfacial charge accumulation, facilitating the extraction of the interfacial oxygen atoms in Cu2-x-O-Ti4-y chains and the surface lattice oxygen on CuO x clusters. Isotope 18O 2 experiments and DFT calculations jointly confirmed that these oxygen atoms preferentially participate in the oxidation through the Mars-van Krevelen mechanism below 250 °C. The resulted oxygen vacancies facilitate the adsorption and activation of O 2 molecules, which will participate the oxidation above 250 °C through Eley-Rideal mechanism. The increase in the temperature also drives the synergy of active oxygen species in the interfacial Cu2-x-O-Ti4-y bond chains and on CuO x clusters, cooperatively promoting the conversion of NO to NO 2. As a result, the CuO x /TiO 2 catalyst exhibits exceptional catalytic performance in soot oxidation, with a four-fold higher reaction rate (4.17 μmol g−1 min−1) than that of single-atom Cu₁-TiO 2 catalyst. Such findings provide a novel strategy for the advancement of Cu-based cluster catalysts in environmental applications. [Display omitted] • Strong CuO x -TiO x interaction favors charge accumulation in interfacial Cu2-x-O-Ti4-y chains. • CuO x clusters (ca. 1 nm) were high-dispersed and anchored by surface TiO x layers. • Temperature drives the synergy of ROSs in interfacial Cu2-x-O-Ti4-y chains and on CuO x clusters. • Soot particles are first oxidized to CO by the in-situ formed NO 2 and then to CO 2 by ROSs. • The intermediate CO acts as a promoter to accelerate the cyclic replenishment of ROSs. [ABSTRACT FROM AUTHOR]

Fe-N-C materials are among the most promising platinum group metals-free catalysts for air cathode of Zn-air batteries (ZABs). However, they are still limited by sluggish reaction kinetics. Herein, we synthesize a novel and effective mesoporous carbon embedded with CoFe nanoclusters, coated with graphitic carbon layers (denoted as CoFe-FeNC). CoFe-FeNC is derived from the pyrolysis of metal-organic complex precursors with grafted iron porphyrin. The CoFe-FeNC catalyst exhibits a half-wave potential (E 1/2) of 0.876 V for the oxygen reduction reaction (ORR) and a potential of 1.526 V at 10 mA cm−2 (E j=10) for the oxygen evolution reaction (OER) in alkaline solutions. Theoretical calculations reveal that the presence of CoFe clusters regulates the electronic structure, optimizing adsorption and desorption during the catalytic reaction. Moreover, flow-ZABs utilizing CoFe-FeNC as the cathode material demonstrate a high specific capacity of 767.5 mAh g Zn −1 and an ultra-long lifespan exceeding 1200 h. Additionally, flexible quasi-solid-state rechargeable ZABs incorporating CoFe-FeNC electrocatalysts as the cathode demonstrate well cycling and mechanical flexibility. [Display omitted] • A facile method for the fabrication of mesoporous nitrogen-carbon material decorated by CoFe clusters (CoFe-FeNC). • CoFe-FeNC showed highly efficient catalytic activities for OER and ORR in alkaline media. • The bifunctional catalysts was employed in flow and flexible Zn-air battery. • Theoretical calculations claim the electronic structure and d-band center modulation between Fe-N-C and CoFe clusters. [ABSTRACT FROM AUTHOR]

[Display omitted] • Platinum group metal atoms confined on the surfaces of BNNT(6,6) with N-vacancy show high stability. • Pt confined inside BNNTs with N-vacancy turns out to be the candidate for CO oxidation, with energy barrier of 0.28 eV via the Langmuir–Hinshelwood mechanism and 0.35 eV. • Spatial confinement effect of BNNT(6,6) contributes to charge transfer between Pt and adsorbed gas, which promotes activation of O 2 and CO. Despite platinum group metal have been widely used in catalytic converters, high cost and reaction temperature hindered their application. Inspired by the single-atom catalysts and confinement effect, selected PGM confined on the boron nitride nanotube with vacancy defects for CO oxidation have been systematically investigated. For PGM–BNNT catalysts, CO oxidation would proceed competitively in Eley–Rideal and Langmuir–Hinshelwood pathways. With N vacancy, Pd/Pt-BNNT(6,6) needs 0.33 and 0.28 eV to overcome the reaction barriers through the LH mechanism. The internal of BNNT will provide a more favorable nano-confinement environment than exterior surface, with the more activated adsorbed gases and electron transfer. [ABSTRACT FROM AUTHOR]

A spectrum of selenium-doped Fe–N–C catalysts is prepared and scrutinized for acidic oxygen reduction reactions to understand the impact of the presence and amount of chalcogen dopants on the catalytic performance as cathode catalyst layers (CCLs) for H 2 –O 2 and H 2 –air polymer electrolyte membrane fuel cells (PEMFCs). While for a high initial content of Se, all available iron is bonded into iron selenides, a low amount of Se doping yields Fe–N–C catalysts of extensive microporosity, increased nitrogen content, and iron occurring predominantly in the Fe-N x coordination state. The chemistry of the iron-carbon-selenium (Fe–C–Se) system is studied in detail to elucidate the impact of Se on Fe–N–C catalyst formation during pyrolysis. The performance of the Se-doped platinum group metal-free Fe–N–C catalysts in PEMFCs is compared with their commercially available counterpart. The effect of the catalysts' morphology alternation by ball-milling on their performance is also studied. It is concluded that chalcogen doping (either S or Se doping) indirectly impacts Fe–N–C catalyst activity by controlling carbon scaffold properties, while the idea of a direct impact of chalcogen atoms on the Fe-N x catalytic centers is challenged. [Display omitted] • Se-doped Fe–N–C catalysts are studied as CCLs in H 2 –O 2 and H 2 –air PEMFCs. • Se-content is varied in a wide range, yielding a large family of Se-doped Fe–N–C. • Se doping grants enhanced microporosity and formation of Fe–N x sites. • Common characteristics of chalcogen-doped Fe–N–C catalysts are identified. • Ball-milling alters catalysts' morphology, thus improving their activity. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) is notorious for its strong adsorption to poison platinum group metal catalysts in the chemical industry. Here, we conceptually distinguish and quantify the effects of the occupancy and energy of d electrons, emerging as the two vital factors in d‐band theory, for CO poisoning of Pt nanocatalysts. The stepwise defunctionalization of carbon support is adopted to fine‐tune the 5d electronic structure of supported Pt nanoparticles. Excluding other promotional mechanisms, the increase of Pt 5d band energy strengthens the competitive adsorption of hydrogen against CO for the preferential oxidation of CO, affording the scaling relationship between Pt 5d band energy and CO/H2 adsorption energy difference. The decrease of Pt 5d band occupancy lowers CO site coverage to promote its association with oxygen for the total oxidation of CO, giving the scaling relationship between Pt 5d occupancy and activation energy. The above insights outline a molecular‐level understanding of CO poisoning. [ABSTRACT FROM AUTHOR]

[Display omitted] Transition metal-nitrogen-carbon (M-N-C) materials have been the focus of scientists' efforts to address the rising need for earth-abundant materials solutions for energy technology and decarbonization of the economy. They are viewed as one of the most promising candidates to replace platinum group metal (PGM) catalysts in the fuel cell and energy conversion fields, including the application of oxygen reduction reaction, carbon dioxide reduction reaction, and nitrogen reduction reaction. In the effort to improve M-N-C materials properties and achieve atomic dispersity of the transition metal in the carbonaceous matrix, a re-pyrolysis process has been proposed. This secondary heat treatment process of already obtained primary pyrolysis-derived M-N-C materials has been widely reported to substantially improve the electrochemical performance and operational stability of the catalysts. Here, we report a systematic investigation of this process used on samples of templated M-N-C catalysts to obtain state-of-the-art catalysts via in situ heating X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), electron energy loss spectroscopy (EELS), X-ray diffraction (XRD), and X-ray computed tomography (CT) characterization methods. It is found that the re-pyrolysis of M-N-C materials could result in the partial amorphization of the carbonaceous substrate. It causes the rearrangement and transformation of multitudinous N moieties, leading to optimization of their morphological display and association with atomically dispersed transition metal dopants. Ultimately, the re-pyrolysis results in an increase in uniformity of the active Fe-N x sites distribution without the formation of nano-crystalline phases (metallic or carbide) and with overall preservation of the morphology of the carbonaceous framework achieved during the first formative pyrolysis step of the templated synthesis. These observations provide confirmation that empirically established re-pyrolysis is recommended to be used on all M-N-C materials despite the different synthesis routes to obtain a practical advanced catalytic material. [ABSTRACT FROM AUTHOR]

Replacing Pt-based catalysts with cost-effective, highly efficient, and durable platinum group metal-free catalysts for the oxygen reduction reaction (ORR) is crucial for commercializing hydrogen fuel cells. Herein, we present a highly active Fe–N–C electrocatalyst that contains both Fe nanoparticles and FeNx active sites derived from an Fe-doped carbonized zeolitic imidazolate framework (ZIF-8). It is found that adjusting the doping amount of Fe in the Fe-doped ZIF-8 precursor alters the morphology of the catalyst after heat treatment. The Fe–N–C-300 composite catalyst with the optimized Fe doping amount exhibits excellent activity, good stability, and remarkable methanol tolerance in the challenging acid environment. This study reveals that a suitable amount of Fe nanoparticles in the catalyst can alter the structure of the FeNx active moieties and increase three-phase boundaries to boost the mass transport, thus leading to improved fuel cell performance. This will have implications for using Fe–N–C catalysts in real applications, as the formation of Fe NPs during the synthesis and reaction is almost inevitable. [ABSTRACT FROM AUTHOR]

A spent catalytic converter was treated with concentrated HCl and hydrogen peroxide in very mild conditions to extract approximately half of its platinum group metals (PGMs) content, mainly as chlorides. The noble metals were subsequently charged into functionalized mesoporous silica by complexation with mercapto groups. A combination of methods was employed to prove the transfer of PGMs and to characterize the materials (inductively coupled plasma optical emission spectrometry [ICP‐OES], Fourier transform‐infrared [FT‐IR] spectroscopy, electrospray ionization mass spectrometry [ESI‐MS], thermogravimetric analysis [TGA], X‐ray photoelectron spectroscopy [XPS], X‐ray diffraction, and UV–Vis spectrophotometry). The resulted PGM‐loaded silica was successfully tested as a new heterogeneous catalyst for hydrosilylation and oxidation reactions. Information about the nature of the PGMs species extracted and loaded completes the existing literature data. The scrap cordierite may be valorized for retention of pollutants from water and also catalyzes the hydrosilylation reaction based on the remaining PGMs. Flexible composite materials can be obtained by incorporating scrap cordierite as filler and crosslinking catalyst into a silicone matrix, significantly enhancing the dielectric permittivity. Thus, complete re‐valorization of the main components of the catalytic converter as high‐added‐value materials was achieved at laboratory level, with very low energy demanding procedures. [ABSTRACT FROM AUTHOR]

S. A. Kondrat, P. J. Smith, J. H. Carter, J. S. Hayward, G. J. Pudge, G. Shaw, M. S. Spencer, J. K. Bartley, S. H. Taylor, and G. J. Hutchings, "The effect of sodium species on methanol synthesis and water-gas shift Cu/ZnO catalysts: Utilising high purity zincian georgeite", Faraday Discussions, 2017, B 197 b , 287-307 P. J. Smith, S. A. Kondrat, P. A. Chater, B. R. Yeo, G. M. Shaw, L. Lu, J.K. Bartley, S. H. Taylor, M. S. Spencer, C. J. Kiely, G. J. Kelly, C. W. Park, and G. J. Hutchings, "A new class of Cu/ZnO catalysts derived from zincian georgeite precursors prepared by co-precipitation", Chemical Science, 2017, B 8 b , 2436-2447. In 1999 Spencer published a paper entitled "The role of zinc oxide in Cu/ZnO catalysts for methanol synthesis and the water-gas shift reaction" in which he reiterated the initial formation of zincian malachite and other Cu/Zn hydroxycarbonates is essential for the later production of small, stable copper crystallites in the operating catalyst [[36]]. Again it was George Bridger's Group which included Phineas Davies[7] that developed two important Cu/ZnO/Al SB 2 sb O SB 3 sb catalysts: low temperature water gas shift catalyst which maximises hydrogen obtained from synthesis gas in ammonia and hydrogen plants, and the low temperature methanol synthesis catalyst that gave high yields of purer methanol than previously available from the high temperature process using ZnO/Cr SB 2 sb O SB 3 sb catalyst. With the passing of Spencer on 3 April 2020 the catalysis community lost a much liked knowledgeable friend especially those from his time at Imperial Chemical Industries (ICI) at Billingham in the North East of England and during his academic career at Cardiff University in Wales. [Extracted from the article]

The oxygen reduction reaction (ORR) is a key process in anion exchange membrane fuel cells. The alkaline conditions should allow silver‐based cost‐efficient catalysts to replace platinum group metal materials. However, Ag electrochemical stability or lack of stability in alkaline medium is still to be demonstrated. Herein, Ag catalyst nanoparticles (NPs) are characterized by identical location transmission electron microscopy and X‐ray photoelectron spectroscopy after electrochemical cycling, revealing the losses of activity and surface. Herein, a facile method for enhancing the chemical stability of Ag catalysts in an alkaline environment by depositing a protective polydopamine (PDA) coating is reported. It is enhanced via crosslinking with polyethyleneimine (PEI), on the surface of Ag NPs. The enhanced electrochemical stability of Ag PDA–PEI nanocatalyst via the analysis of ORR polarization curves during accelerated stress test cycling is demonstrated, with at least one order of magnitude higher durability than the standard Pt/C catalyst. Moreover, electrochemical measurements indicate that the protective PDA–PEI coating has good permeability to O2, with a positive effect on the ORR activity of Ag NPs. [ABSTRACT FROM AUTHOR]

The limited annual mining capacity and high costs of platinum metal group catalysts (PMG) are confining the production of hydrogen from PEM electrolysis. Therefore, a significant reduction of catalyst needs is crucial to reduce system costs and increase production capacity. This study demonstrates the feasibility of a PEM water electrolysis cell design using porous transport electrodes (PTE) with catalyst coating by atomic layer deposition (ALD) and operation in 1 mol/L sulphuric acid at 60 °C. Though the catalyst loading has been reduced to 0.12 mg/cm2 iridium on the anode and 0.28 mg/cm2 platinum on the cathode, a current density of 168 mA/cm2 and mean high mass activity of 1400 A/g iridium could be achieved at 1.7 V. The characterization of three high loading PTE cells is combined with a detailed overpotential analysis from polarization curve fits and demonstrates a reproducible cell setup. Further analysis steps show an increasing cell performance with increasing coating cycle numbers and the consistency of the anode performance in the three electrode setup with the complete cell. The ALD coated PTE design turns out to be a promising candidate for catalyst loading reduction in PEM electrolysis. • Demonstration of a cell design with porous transport electrodes and atomic layer deposition. • Reduction of catalyst at high mass activity. • Experimental characterization combined with a detailed overpotential analysis from polarization curve fits [ABSTRACT FROM AUTHOR]

[Display omitted] • Enhanced C 3 H 8 oxidation activity of perovskites etched by oxalic acid. • Abundant Co2+ Lewis acid sites with reactive dangling bonds after etching. • Better reducibility and oxygen activation ability ascribed to more Co2+ sites. • More facile C 3 H 8 adsorption and activation due to the population of Co2+ sites. Perovskite oxides have emerged as promising alternatives for the supported Platinum group metal catalysts for total oxidation of propane and other volatile organic compounds (VOC). Here, we report a surface modification method to improve propane oxidation activity of La 0.8 Sr 0.2 CoO 3 monolithic catalysts using diluted oxalic acid etching. The oxalic acid treatment decreases the light-off temperatures of propane oxidation by 30–40 °C. Experimental and DFT investigations reveal that the treatment selectively etches Sr cations and slightly reduces LSCO surface, leading to an increased population of low-valence Co2+ Lewis acid sites, which promotes activation of lattice oxygen and adsorbed oxygen species and facilitates propane adsorption and dissociation. Our work offers a rapid strategy to activate perovskite monolithic catalysts and will inspire the research on surface modification of perovskite catalyst. [ABSTRACT FROM AUTHOR]

Fuel cells are today among the most efficient and environmentally friendly devices for the production of electricity. They are developing rapidly and are already in the early stages of commercial implementation. Solid oxide fuel cells (SOFCs) are largely promising as they show the highest efficiency and flexibility (H2, CnHm, CO, etc.) and do not need platinum group catalysts. Much attention is paid to improving the structure of SOFCs to increase their electrical properties. Different research groups commonly study the electrical properties of SOFCs under different conditions depending on the available equipment and the capabilities of their laboratories; this complicates an overall comparison between the electrical properties of fuel cells. In this regard, this research focuses on establishing the dependence of the specific electrical power (P0.7) at 0.7 V voltage for SOFCs on the hydrogen concentration in model fuel (a mixture of hydrogen and inert gas), other experimental conditions being equal. The specific electrical power P0.7 was chosen as one of the most important indicators for SOFC operation in power systems. The experimental dependence of P0.7 on the hydrogen concentration (CH2) in model fuel for different SOFCs was fitted with the least squares method to polynomial, logarithmic, and linear functions and the factor of coincidence (determination factor R2) with the experimental data was calculated. The quadratic and linear fitting functions were found to be most accurate among the functions considered and showed an average relative fitting error of no more than 9 and 12%, respectively. The prospects of the proposed hypothesis are that the fitted dependences of the SOFC electrical indicators can be used not only to predict the electrical properties of SOFCs in different operating conditions but also to facilitate the comparison of their electrical properties. [ABSTRACT FROM AUTHOR]

Z-Olefins are challenging synthetic targets owing to their relative thermodynamic instability. Transition metal–catalyzed asymmetric allylic substitution reactions are well known for installing stereocenters adjacent to branched or E-linear olefins. However, analogous reactions for the synthesis of optically active Z-olefin products are rare. Here we report iridium-catalyzed asymmetric allylic substitution reactions that retain Z-olefin geometries while establishing an adjacent quaternary stereocenter. The formation of transient anti-p-allyl-iridium intermediates and their capture by external nucleophiles before isomerization to the thermodynamically more stable syn-p-allyl-iridium counterparts have been observed. These results provide a promising method for preparing chiral Z-olefinic compounds. [ABSTRACT FROM AUTHOR]

The article explores how catalysts will play a role in tackling major issues such as energy consumption and environmental degradation. Topics the catalytic reduction of carbon dioxide (C02) to fuels or chemical building blocks has the potential to recycle and valorize a problematic waste gas; and catalytic oxidation is a well-established technique for the removal of pollutants such as nitrogen oxide (NOx )and volatile organic compounds (VOCs) from waste streams.

The use of automotive catalysts has been increasing in recent decades. With the strict regulations governing the emission of polluting gases, the number of catalysts that are discarded also grows, generating enormous volume of waste, which can be a source for urban mining. The objective of this work is to characterize deactivated automotive catalysts in terms of mineralogical, structural and elemental composition, quantitatively and qualitatively. The analyzes were performed in granulometry by laser diffraction, X-ray diffractometer (XRD), scanning electron microscope with X-ray energy dispersion spectroscopy (SEM / EDS), Raman spectroscopy and inductive coupling plasma optical spectrometry (ICP-OES). The studied automotive catalyst presented cracks and contaminants such as P, Ca, F, C and S, accentuating the deactivation process. The largest composition identified was cordierite, corresponding to 40.17%. The catalysts of the platinum group identified in the automotive catalyst were, Pd (0.92%), Pt (0.03%) and Rh (0.17%). [ABSTRACT FROM AUTHOR]

Platinum group metal-free catalysts for polymer electrolyte fuel cells are analyzed in different electrolytes (H2SO4 and HClO4) and at different pH values to gain insight into the oxygen reduction reaction (ORR) mechanism. Two Fe-N-C type catalysts showing a reversible voltammetric redox couple around 0.77 V vs RHE in HClO4 electrolyte are investigated. A notable cathodic shift of the redox couple to 0.62 V is observed in H2SO4 and is assigned to bisulfate adsorption. Concurrently, the ORR activity of the catalysts is unaffected, suggesting an independent nature of the reductive mechanism with the redox peak species. [ABSTRACT FROM AUTHOR]

Cu electrodeposition in both underpotential and overpotential regimes on nanostructured MoS2 and WS2 prepared by plasmaenhanced atomic layer deposition has been studied in detail. A combination of electrochemical methods, advanced characterization by X-ray absorption spectroscopy (XAS) as well as theoretical modelling were employed to reveal Cu adsorption modes on transition metal dichalcogenides (TMDs) from initial stages until bulk deposition. Since Cu UPD on TMDs has been used recently to evaluate the number of electrochemically active sites (NAS) for H2 evolution reaction, we evaluate and discuss here the implications of the Cu electrodeposition phenomena on nanostructured MoS2 and WS2 gauging the general applicability of the Cu UPD method for number of HER active sites determination in TMDs. Although an apparently better correlation of HER current density with Cu UPD charge than with double layer capacitance is found, the Cu UPD method cannot be used quantitatively because of the absence of a clear H UPD phenomenon on the studied nanostructured TMDs. This is in contrast to platinum group metal catalysts where H UPD and Cu UPD sites are strongly correlated. [ABSTRACT FROM AUTHOR]

Platinum‐group‐metal‐free (PGM‐free) catalysts are the most promising materials to substitute expensive platinum catalysts for efficient oxygen reduction reaction (ORR), particularly for microbial fuel cells. For these devices, contamination due to wastewater is one of the major issues, owing to the presence of various poisoning anions. The known nitrite contamination effect over PGM‐free catalysts was studied by using the rotating disk electrode (RDE) technique in neutral media to understand its patterns. The results were then compared to other contaminants commonly found in wastewater such as chloride (Cl−), perchlorate (ClO4−), and nitrate (NO3−) in the concentration range of 0.05–50 mM. Onset potential (Eonset), half‐wave potential (E1/2), limiting disk current density (Jlim) and Tafel slope variations were the parameters exploited to identify specific or nonspecific adsorbed contaminants. Chloride and nitrate had no negative effect on ORR performance, whereas perchlorate slightly reduced the catalyst function with no permanent issues. Durability tests (1000 cycles) were also performed to ensure the stability of the catalyst for the relatively long time. [ABSTRACT FROM AUTHOR]

Conversion of methane towards chemical feedstocks such as oxygenates and hydrocarbons has been studied along with the development of natural gas technology. In this study, CO‐assisted direct conversion of methane into C1 and C2 oxygenates was demonstrated over ZSM‐5 supported transition and platinum group metal catalysts. Besides previously investigated Rh, other platinum group metals (e. g., Ru and Ir) were found to be a potential element as the catalyst. Presence of CO was critical for the reaction, which would work as a ligand, a reductant, and a reactant. On the other hand, the competing undesired CO oxidation toward CO2 was found to be the major issue. Partial oxidation toward methanol or formic acid (C1 oxygenates formation) was parallel to oxidative carbonylation to acetic acid (C2 oxygenate formation). [ABSTRACT FROM AUTHOR]

[Display omitted] • A rapid and facile nonsolvent-induced film formation (NIFF) method is developed. • Dense PAP-based AEMs are prepared within seconds from high-boiling-point solvents. • The protective gel layer at the polymer/solvent–nonsolvent interface plays a pivotal role. • PAP-based cells achieve an equivalent current density of 910 mA cm−2 at 2.0 V, 20 % higher than commercial FAA-3-50 cells. Transparent, dense, and freestanding polymer membranes are typically prepared by solution casting (SC). However, SC is a time-consuming (>24 h) multi-step process that requires high-temperature vacuum treatment. Here, we report a rapid and facile method—nonsolvent-induced film formation (NIFF)—for preparing dense, freestanding membranes by immersing a polymer solution in a nonsolvent, using two types of poly(arylene piperidinium) (PAP) and their quaternized versions. Thermodynamic, kinetic, and molecular dynamics analyses of polymer/solvent/nonsolvent ternary systems reveal that the PAP polymers have high affinities for the nonsolvent (water), yielding a gel between homogeneous and heterogeneous regions. The protective gel layer at the polymer/solvent–nonsolvent interface averts penetration of the nonsolvent and permits withdrawal of the solvent from the polymer solution, forming a nonporous dense membrane. The physicochemical, mechanical, morphological, and electrochemical characteristics of NIFF- and conventional-SC-derived membranes are comparable. Moreover, the alkaline water electrolysis cell performance is evaluated using the membranes and platinum group metal-free catalyst. Both NIFF- and SC-derived membrane-based cells achieve an equivalent current density of 910 mA cm−2 at 2.0 V, which is 20 % higher than commercial FAA-3-50 membrane-based cells. This study establishes an innovative strategy to facilely fabricate freestanding polymer films with a time- and energy-saving process for ion-conducting membranes. [ABSTRACT FROM AUTHOR]

• Fe-N-C catalyst was prepared using FePc, dicyandiamide and CDC/graphene composite. • DCDA helps to mitigate metal agglomeration and boosts Fe-N x active site formation. • FeN-CDC/G/DCDA catalyst (E 1/2 = 0.76 V) outperforms FeN-CDC/G catalyst (E 1/2 = 0.70 V) • RRDE results display good selectivity for 4e− ORR pathway of FeN-CDC/G/DCDA (n = 3.9) The focus in the development of catalysts doped with transition metals aims to replace platinum group metal catalysts in fuel cells. However, these non-precious metal catalysts exhibit limited performance in acidic environment for the oxygen reduction reaction (ORR) due to issues such as metal agglomeration and the subsequent loss of active sites. Herein, we synthesised catalysts doped with iron and nitrogen on a composite material consisting of carbide-derived carbon (CDC) and graphene (G), employing an additional nitrogen source dicyandiamide (DCDA), denoted as FeN-CDC/G/DCDA. Our physico-chemical analysis unveiled that the inclusion of DCDA was effective in mitigating metal agglomeration during the synthesis process and increasing the presence of Fe-N x sites in the catalysts. Notably, the FeN-CDC/G/DCDA catalyst exhibited enhanced ORR activity in acid media with half-wave potential (E 1/2) of 0.76 V, surpassing the performance of the FeN-CDC/G catalyst, which had an E 1/2 value of 0.70 V. Furthermore, the rotating ring-disk electrode results indicated a reduced formation of hydrogen peroxide when employing the FeN-CDC/G/DCDA catalyst. The findings from this study represent a significant step towards the development of efficient catalysts for fuel cells, underscoring the pivotal role of additional nitrogen doping and its positive impact on the ORR performance. [ABSTRACT FROM AUTHOR]

Fe-based platinum group metal (PGM)-free catalysts were incorporated into electrospun fiber mat or powder cathode membrane-electrode-assemblies (MEAs) with a Nafion 211 membrane and a Pt/C powder anode. Fabrication and characterization tests were performed on MEAs with: (1) a conventional powder cathode with a neat Nafion binder, (2) a fiber mat cathode with a Nafion/polyethylene oxide (PEO) binder, where PEO was extracted before MEA testing, (3) a powder cathode with a blended binder of Nafion and polyvinylidene fluoride (PVDF), and (4) a series of fiber mat cathodes with different Nafion/PVDF binder weight ratios. Cathode degradation occurred, with a loss in power output, in MEAs with a neat Nafion powder cathode or with a Nafion fiber cathode. In contrast, little or no power loss was observed for powder or fiber cathodes when the binder was a blend of Nafion and PVDF. The presence of hydrophobic PVDF drove water and electrogenerated peroxide out of the cathode, away from catalyst particles, which improved cathode durability, but PVDF also decreased the binder conductivity and slowed oxygen reduction kinetics, resulting in lower power densities. A 75:25 w:w Nafion:PVDF fiber cathode MEA was the best compromise for maximizing power and minimizing catalyst degradation. For such a cathode, with a PGM-free cathode catalyst loading of 3.0 mg cm−2, a power density of 88 mW cm−2 at 0.5 V, 80 °C, and 200 kPa abs pressure was maintained for 80 h of continuous operation. [Display omitted] • Nanofiber cathode MEAs with PGM-free catalyst were fabricated and tested. • Cathodes were evaluated with neat Nafion and Nafion/PVDF binders. • The Nafion fiber cathode MEA produced high power initially but degraded over time. • Stable MEA power output was achieved with Nafion/PVDF fiber cathodes. [ABSTRACT FROM AUTHOR]

Alkaline anion-conducting polymer-based CO 2 electrolysis and water electrolysis are among two emerging renewable energy conversion technologies. Their system design and integration offer promise of lower capital cost due to utilization of low-cost catalysts, in contrast to platinum group metal catalysts required for cation-conducting polymer-based devices. However, a critical component, the polymer electrolyte membrane, remains an obstacle hampering system performance and durability. In this study, commercially-available Sustainion® membranes with and without PTFE-reinforcement were investigated to understand previously unreported origins of improved device performance when compared to alternative membrane chemistries. We report critical membrane properties, such as morphology, thermal stability, as well as temperature-, hydration-, and counter-ion dependent ion conductivity. Moveover, the changes in uptake and conductivity of membranes in supporting electrolytes of K 2 CO 3 and KOH investigated as a function of their concentration. Presence of reinforcement and supporting electrolyte type alter the membrane's transport functionality, which could help guide device design for improved performance. The obtained results not only show how Sustainion® properties change with operating environment for CO 2 and water electrolysis applications, but also provide understanding for internal and external factors controlling anion-exhcnage membrane functionality in electrochemical devices. [Display omitted] • Structure-properties of Anion-Exchange Membranes (AEMs) with and without reinforcement were investigated in external environments. • Hydration and conductivity are reported as a function of temperature, hydration, and counter-anion forms. • AEM uptake and conductivity in supporting electrolytes of K 2 CO 3 and KOH are measured as a function of concentration • Reinforcement alters electrolyte uptake and conductivity differently, creating an interplay between internal-external design parameters [ABSTRACT FROM AUTHOR]

With the rapid increase of new energy industry, the shortage of critical metals for new energy industry, such as Ni, Co, V, and Pt, has received global attention. The hazardous spent catalysts from traditional energy industry contain a series of critical metals, which should be safe disposal and even value-added utilized. However, the recovery of critical metals from these valuable wastes has not been well accepted. In this review, the characteristics and recycling necessity of spent catalysts are described in the start section, and then the current progress on stepwise recycling techniques of three typical spent catalysts are summarized, which are petroleum refining hydrogenation catalysts, platinum group metals catalysts and selective catalytic reduction catalysts. The regeneration and value-added utilization examples of these catalysts have been discussed and prospected. An overview of the advantage and disadvantage features of these techniques is presented, associating with the environmental assessment. At the end of the paper, the evolutions of metal elements and species of the recycling process are emphasized for rational designs and considerations from the mechanism of molecular level. The further perspective on the more practical value-added utilization is highlighted. This review set up a closed-loop conversion bridge from traditional energy wastes to new energy materials. Critical metal resource recycling of spent catalysts is a bridge connecting the traditional energy industry and the new energy industry. [Display omitted] • Current recycling techniques and necessities of hazardous spent catalysts are reviewed and summarized. • The spent HDS catalysts, PGMs catalysts and SCR catalysts are selected as three typical hazardous catalysts. • The value-added utilization has been highlighted as future directions of recycling process. • The evolutions of metal elements and present species in aqueous solutions are described. [ABSTRACT FROM AUTHOR]

The development of platinum group metal-free catalysts is considered the most prominent path for reducing the cost of low-temperature fuel cells (LTFC). Despite the great advancement in the field, its further progress is currently limited by the ability to understand and mitigate the catalysts' degradation mechanisms, which up to recent years was limited by the lack of activity descriptors. Recent work showed that this could be solved using Fourier-transformed alternating current voltammetry that enables to deconvolute Faradaic currents arising from the redox reaction of the active sites from the capacitive currents, and by that accurately measure the electrochemically active site density of these catalysts in situ fuel cells. However, the analysis of the results can be complex, requiring simulation software for accurate parameter extraction. Herein, a simplified analysis of Fourier-transformed alternating current voltammetry is presented. This was done by mapping the influence of various variables, such as resistivity, capacitance, and thermodynamic and kinetic dispersion, on the accuracy of electrochemically active site density measurements. Under specific, yet realistic, operating conditions, a single equation with the peak current of the 5th harmonic as the only variable can be used to quantify electrochemically active site density with high accuracy. This approach was demonstrated using molecular catalysts, iron phthalocyanine, as a model molecule, and a commercial, heat-treated catalyst. Free analysis software is also provided to facilitate the easy use of this method. [ABSTRACT FROM AUTHOR]

For this reason, new technologies for next-generation hybrid engines are required to reduce the emissions at the engine-out level and improve the performance of the aftertreatment system. Electrified powertrains have appeared in recent years as part of the solution to achieve the aggressive targets established for a reduction in greenhouse gas emissions, particularly CO SB 2 sb . While EGR is being widely used for improving the efficiency of new-generation spark ignition engines for hybrid applications, it has a negative impact on combustion performance and, particularly, on unburned hydrocarbon emissions. [Extracted from the article]