Anode Electrocatalyst Research Articles

Rapid Scalable One‐step Production of Catalysts for Low‐Iridium Content Proton Exchange Membrane Water Electrolyzers

AbstractProton exchange membrane water electrolysis (PEMWE) is a promising technology for green hydrogen production, although its widespread development with state‐of‐the‐art loadings is threatened by the scarcity of iridium (Ir). Homogeneous dispersion of Ir in an immiscible electro‐ceramic matrix can enhance catalytic mass activity and structural stability. The study presents IrySn0.9(1−y)Sb0.1(1−y)Ox solid solutions produced by highly scalable flame spray pyrolysis (FSP) process as efficient anode electrocatalysts for PEMWE, containing only 0.2 mg cm−2 of Ir in the catalyst layer (CL). Intense mixing of metal vapor and large thermal gradients in the precursor‐derived high‐temperature flame aids stabilizing sub‐nanoscale entropic mixing within self‐preserved 4–6 nm particles. Detailed investigations confirm that the one‐step prepared solid solution electrocatalysts exhibit up to fourfold higher activity toward the oxygen evolution reaction (OER) compared to Ir black. The anode of a PEMWE utilizing this catalyst exhibits high performance and stability over 2000 h but with tenfold lower Ir loading than the state‐of‐art.

Pinning effect of lattice Pb suppressing lattice oxygen reactivity of Pb-RuO2 enables stable industrial-level electrolysis.

Ruthenium (Ru) is widelyrecognized as a low-cost alternative to iridium as anode electrocatalyst in proton-exchange membrane water electrolyzers (PEMWE). However, the reported Ru-based catalysts usually only operate within tens of hours in PEMWE because of their intrinsically high reactivity of lattice oxygen that leads to irrepressible Ru leaching and structural collapse. Herein, we report a design concept by employing large-sized and acid-resistant lattice lead (Pb) as a second element to induce apinning effect for effectively narrowing the moving channels of oxygen atoms, thereby lowering the reactivity of lattice oxygen in Ru oxides. The Pb-RuO2 catalyst presents a low overpotential of 188 ± 2 mV at 10 mA cm-2 and can sustain for over 1100 h in anacid medium with a negligible degradation rate of 19 μV h-1. Particularly, the Pb-RuO2-based PEMWE can operate for more than 250 h at 500 mA cm-2 with a low degradation rate of only 17 μV h-1. Experimental and theoretical calculation results reveal that Ru-O covalency is reduced due to the unique 6s-2p-4d orbital hybridization, which increases the loss energy of lattice oxygen and suppresses the over-oxidation of Ru for improved long-term stability in PEMWE.

Activation of iridium site based on IrO2 catalysts towards highly stable PEM water electrolyzer

The exploitation of anode electrocatalysts with high activity and stability remains an enormous challenge in proton exchange membrane (PEM) water electrolyzer. Here we doped Mn to activate Ir site in IrO2 through the molten salt sealing method, and the optimized Mn0.1Ir0.9O2 exhibited superior OER performance. Mn doping optimized the electronic structure and dominant crystal planes of IrO2, as evidenced by our complementary characterizations. Impressively, the Mn0.1Ir0.9O2 exhibits superior performance in the PEM water electrolyzer, only requiring 1.79 V to attain 1 A cm−2 and offering long-term stability over 1200 h (attenuated only 17.5 μV h−1 compared to 1.27 mV/h for the original sample). DFT calculation shows Mn doping could activate Ir site, thus reducing the energy barrier of the rate-determining step for promoting OER. This work provides a strategy to design high-tolerance catalysts for the PEM water electrolyzer in actual working conditions.

Ex Situ Electro‐Organic Synthesis – A Method for Unrestricted Reaction Control and New Options for Paired Electrolysis

AbstractClassic in situ electro‐organic synthesis with substrates in an electrolyzer must compromise process conditions to balance electro‐ and thermochemical steps at both electrodes. This often restricts efficiency and product selectivity, since requirements may deviate for electrochemical (catalyst activation) and chemical (organic synthesis) steps, as well as for paired anode‐ and cathode reactions. Breaking this barrier, we report ex situ electro‐organic synthesis as a versatile method that enables unique product selectivity and unusual product pairs. We exemplify the concept for pairing H2 evolution (HER) with anodic alcohol oxidation. The two‐step method accomplishes this by separating cathode reactions from organic substrate oxidation, and anodic electrocatalyst activation from chemical conversion of organic substrates in time and space. First, the electro‐oxidation of Ni(OH)2 anodes to NiOOH is paired with H2 production by alkaline water electrolysis. Then, “charged” NiOOH electrodes are removed from the electrolyzer and used in external vessels to oxidize model substrate benzyl alcohol under regeneration of Ni(OH)2. Free choice of reaction media outside the electrolyzer allows to selectively obtain benzoic acid (in water) or benzaldehyde (in n‐hexane), whereas classic in situ electrosynthesis only produces the acid together with H2. Perspectively, the method enables electrosynthesis of previously inaccessible products paired to H2 generation.

Chemical Bath Deposition of NiFe Alloy Anode for Efficient Alkaline Water Electrolyzer Integration.

Green hydrogen production from water splitting is a feasible way for intermittent renewable energy storage and utilization, where the exploration and scale-up preparation of high-performance anodic oxygen evolution electrocatalysts are critical prerequisites for its industrial-level applications. Herein, a chemical bath deposition of FeNi3 intermetallic alloys onto Ni mesh support is performed, which delivers a current density of 0.62 Acm-2 at 1.72 V versus reversible hydrogen electrode for alkaline water oxidation in 1 m KOH and an excellent electrolysis stability at 0.2 A cm-2 for over 300 h. Moreover, via 3D computational fluid dynamics simulation and flow field optimization, a homogeneous deposition of ≈5400 cm2 NiFe anode is demonstrated within 4 min using the developed flow bath reactor. Once integrating the as-prepared NiFe anodes into alkaline electrolyzer stack, the voltage variation between each unit cell is below 40 mV at a total operation current of 71 A, or ca. current density of 0.2 A cm-2, confirming the uniformity of this batch synthesis protocol and its great potential for industrial alkaline water electrolysis.

Pt-decorated oxygen-vacancy-tuned high temperature hydrogen-annealed WO3 as an efficient anode electrocatalyst for PEMFC

One of the most significant steps for the widespread application of Proton Exchange Membrane Fuel Cells (PEMFC) is the development of an efficient and corrosion-resistant electrocatalyst for Hydrogen Oxidation Reaction (HOR). To achieve an enhanced electrocatalytic activity towards HOR, we developed a carbon-free electrocatalyst that performs on par with the Pt/C commercial-based catalyst. Pt nanoparticles dispersed on hydrogenated WO3 surfaces were synthesized and experimentally shown to be an efficient HOR electrocatalyst. Furthermore, different characterizations and electrochemical studies validate the performances of all the hydrogenated samples. Pt/a-WO3/H400, hydrogenated at 400 °C, exhibits excellent electrocatalytic activity in terms of onset potential, limiting current density, and electrochemical surface area (ECSA). The membrane electrode assembly (MEA) was fabricated, and its single-cell performance was carried out using Pt/a-WO3/H300, Pt/a-WO3/H400, and Pt/a-WO3/H500 at the anode with Pt loading of 0.125 mg/cm2. The single-cell performance of Pt/a-WO3/H400 as anode electrocatalyst has the highest power density (540 mW/cm2) at 50 °C and high durability, compared to Pt/C. The enhanced electrocatalytic performance is attributed to the synergistic catalytic effect between Pt nanoparticles and the WO3-x interface. This occurs due to the preferential orientation of the highly active (002) facet and the creation of an optimum amount of oxygen vacancies due to the hydrogenation impact.

Lanthanides in the water electrolysis

AbstractThe most feasible technique for producing green hydrogen is water electrolysis. In recent years, there has been significant study conducted on the use of transition metal compounds as electrocatalysts for both anodes and cathodes. Peoples have attempted several strategies to improve the electrocatalytic activity of their original structure. One such technique involves introducing rare earth metals or creating heterostructures with compounds based on rare earth metals. The incorporation of rare earth metals significantly enhances the activity by many folds, while their compounds offer structural stability and the ability to manipulate the electronic properties of the original system. These factors have led to a recent boom in investigations on rare earth metal‐based electrocatalysts. There is currently a pressing demand for a review article that can provide a comprehensive overview of the scientific advancements and elucidate the mechanistic aspects of the impact of lanthanide doping. This review begins by explaining the electronic structure of the lanthanides. We next examine the mechanistic aspects, followed by recent advancements in lanthanide doping and heterostructure formation for water electrolysis applications. It is expected that this particular effort will benefit a broad audience and stimulate more research in this area of interest.image

Mesoporous Hollow Carbon Sphere-Embedded MXene Architectures Decorated with Ultrafine Rh Nanocrystals toward Methanol Electrooxidation.

The development of advanced Pt-alternative anode electrocatalysts with high activity and reliable stability is critical to overcoming the technical challenges of direct methanol fuel cells. Here, we propose a robust bottom-up strategy for the spatial construction of mesoporous hollow carbon sphere (HCS)-embedded MXene architectures decorated with ultrafine Rh nanocrystals (Rh/HCS-MX) via stereoscopic coassembly reactions. The rational intercalation of HCS effectively separates the MXene nanowalls to achieve a rapid mass-transfer efficiency, while the intimate coupling of the hybrid carrier with Rh nanocrystals enables their electronic structure optimization, thus contributing to strong synergistic catalytic effects. Accordingly, the resulting Rh/HCS-MX architectures exhibit outstanding methanol electrooxidation properties in terms of large electrochemical active surface areas, high mass/specific activities, and good long-term stability, all of which are significantly superior to the traditional Rh/carbon black, Rh/HCS, and Rh/MXene as well as commercial Pt/carbon balck and Pd/carbon balck electrocatalysts.

High-performance direct borohydride-hydrogen peroxide fuel cell using Ni foam-supported Ni-Co nanoparticles as a noble-metal free anode electrocatalyst

The Ni-Co nanoparticles with various Ni/Co ratios are immobilized on a Ni foam (NF) template, coated with reduced graphene oxides (rGO), and used as a novel noble-metal-free anode electrocatalyst for enhanced performance direct borohydride fuel cells. The electrochemical active surface area (EASA) of Ni50Co50 /rGO/NF (1515 cm2) catalyst is 45.5 times larger than NF (33.3 cm2). A comprehensive study of direct borohydride-hydrogen peroxide fuel cell (DBHPFC) by Pt/C (0.5 mg cm−2) as a cathode and Ni50-Co50/rGO/NF as an anode is accomplished, so an open-circuit potential (OCP) of 1.90 V and the maximum power density of 309 mW cm−2 is obtained at 60 ◦C. These results show that electrocatalyst Ni50Co50/rGO/NF is a suitable candidate for use as an electrocatalyst in DBHPFC due to its low cost, ease of synthesis, excellent structural stability, and high catalytic performance.

Investigating the impact of various etching agents on Ti3C2Tx MXene synthesis for electrochemical energy conversion

MXenes represent a revolutionary class of two-dimensional (2D) materials that have garnered significant attention due to their unique properties, including excellent electrical conductivity, and remarkable mechanical strength. This study investigates the influence of different etching agents on the synthesis of MXenes for electrochemical energy conversion applications, particularly in methanol oxidation reactions (MOR). Morphological characterization, particle distribution and sizing, elemental analysis, and surface chemistry assessments were conducted using field emission scanning electron microscopy (FESEM), elemental mapping, transmission electron microscopy (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). Electrochemical techniques such as cyclic voltammetry (CV), electrochemical active surface area (ECSA), Tafel analysis, electrochemical impedance spectroscopy (EIS), and long-term stability assessment were employed. The study reveals that PtRu/MXene synthesized with the FeF3/HCl etching route exhibits the highest ECSA value and peak current density, being 12.3 times and 3.63 times higher than those achieved via the LiF/HCl etching route. The kinetic rate, tolerance to catalyst poisoning and long-term stability also show the better results for this etching route. These findings suggest promising potential for PtRu/MXene_FeF3/HCl as an effective anodic electrocatalyst in direct methanol fuel cell (DMFC) applications.

Investigating the Effect of KOH Feed Concentration on a Stainless-Steel Anode Using a 3-Electrode Anion Exchange Water Electrolyser Cell Set-up

Anion-exchange membrane water electrolysers (AEM-WE) have the potential to lower the capital cost of hydrogen production compared to proton-exchange membranes water electrolysers (PEM-WE). The alkaline conditions of AEM-WE result in: (i) a kinetically more favourable oxygen evolution reaction (OER), (ii) the ability to use platinum group metal (PGM)-free metal catalysts, and (iii) reduced cell component costs because of the less corrosive operating conditions. However, AEM-WE is held back from commercialisation by limited current density and durability.1 Compared to conventional alkaline water electrolysis, AEM-WEs have the advantage of lower ohmic resistance thanks to a solid polymer electrolyte which provides intrinsic ionic conductivity instead of relying on 6 M KOH and a porous separator. Most studies show, however, that a dilute KOH feed (< 1 M), rather than pure water, is critical to reaching a high current density in AEM-WE. Varying the concentration of KOH in the feed solution impacts catalyst activity and membrane resistance thereby making performance measurements in AEM-WE more complex. Moreover, the overpotential for the alkaline hydrogen evolution reaction (HER) is significant due to its sluggish kinetics. This means full-cell measurements are insufficient for understanding the behaviour of OER and HER catalysts in AEM-WE. It is therefore crucial to make half-cell measurements in AEM-WEs to decouple the effect of the anode and cathode electrocatalysts from the overall cell performance.In this context, our group recently demonstrated a 3-electrode, 5 cm2 membrane electrode assembly electrolyser cell2 that uses a reference electrode to decouple the anode and cathode contributions to the overall water splitting reaction. The technique was demonstrated for AEM-WEs and is soon to be published by Malone et al. (Figure 1A)3. In this study, we aimed to investigate the effect of KOH concentration in the feed solution on OER by using this 3-electrode cell setup. We used a stainless steel (SS)-felt at the anode as both catalyst and porous transport layer (PTL) in different concentrations of KOH feed while maintaining Pt/C as the cathode catalyst. We also repeated the tests with various anode catalyst layers (IrOx, NiFeOx) in combination with the SS PTL. For each test, full and half-cell polarisation curves and impedance spectroscopy were recorded before and after a sixteen-hour durability test at 1 A cm-2 at 40 °C. The results revealed the catalytic significance of the SS-felt in 1 M KOH as recently shown by Chen et al.4 Additionally, we demonstrated how the SS masks the performance of an IrOx catalyst layer in 1 M KOH. Reducing the KOH concentration to 0.18 M resulted in ≈ 7 % increase in the overall cell voltage at 1 A cm-2 (from 1.88 V to 2.00 V at 40 °C in Figure 1B). Aside from the ≈ 35 % increase in membrane resistance (e.g. 180 to 240 mΩ cm2 at 0.9 A cm-2) in 0.18 M KOH, the higher overpotential arose from the anode (Figure 1C), which could be attributed to the higher OER overpotential of SS-felt in a lower pH solution. Meanwhile, there was no appreciable change in cathode overpotential when the KOH concentration was reduced. These findings demonstrate the importance of 3-electrode cell measurements for understanding the impact of each component in an AEM-WE cell. Furthermore, the results reveal that both the choice of PTL material as well as the concentration of feed solution should be considered when testing different catalysts in AEM-WE.

Iridium-Based Electrocatalysts for Oxygen Evolution Reaction in Proton Exchange Membrane Water Electrolyzers

Proton exchange membrane water electrolyzers (PEMWEs) show the fast response to a wide electrical load range, making them compatible to couple with intermittent renewable energy systems such as wind and solar power. However, the low efficiency, instability, and high cost of anodic electrocatalysts for the oxygen evolution reaction (OER) severely hinder the widespread deployment of PEMWEs. Hitherto, iridium-based catalysts still play an irreplaceable role for their trade-off catalytic activity and stability. To meet the scarcity of iridium, reducing the iridium loading and designing low iridium-based electrocatalysts have become the mainstream. Particularly, perovskite-type oxides possess flexible compositions, enabling them ideal material platform for the optimization of catalytic performance. In this work, several materials of iridium-based perovskite-type oxides were acquired by coupling iridium with various transition elements in B-site and regulating A-site cations, which both diluted the usage of iridium and utilized the multi-metallic synergistic effect to achieve high activity and stability. Evolution of the surface structure was monitored by in-situ Raman spectroscopy to identify the active site and to uncover the catalytic mechanism. Besides, density functional theory (DFT) calculation was used as an auxiliary tool to analyze the local structure and electrochemical behavior of the electrode surface for its cost-effectiveness. Furthermore, membrane electrode assembly (MEA) based on the optimum composition was assembled to evaluate the performance of novel electrocatalysts for PEMWEs. Results of this work provide a new perspective of designing low iridium content electrocatalysts for OER in PEMWEs. Acknowledgement This work is funded by the National Natural Science Foundation of China (No. 22002089, 52072239).

Bifunctional Oxygen-Defect Bismuth Catalyst toward Concerted Production of H2O2 with over 150% Cell Faradaic Efficiency in Continuously Flowing Paired-Electrosynthesis System.

The electrosynthesis of hydrogen peroxide (H2O2) from O2 or H2O via the two-electron (2e-) oxygen reduction (2e- ORR) or water oxidation (2e- WOR) reaction provides a green and sustainable alternative to the traditional anthraquinone process. Herein, a paired-electrosynthesis tactic is reported for concerted H2O2 production at a high rate by coupling the 2e- ORR and 2e- WOR, in which the bifunctional oxygen-vacancy-enriched Bi2O3 nanorods (Ov-Bi2O3-EO), obtained through electrochemically oxidative reconstruction of Bi-based metal-organic framework (Bi-MOF) nanorod precursor, are used as both efficient anodic and cathodic electrocatalysts, achieving concurrent H2O2 production at both electrodes with high Faradaic efficiencies. Specifically, the coupled 2e- ORR//2e- WOR electrolysis system based on such distinctive oxygen-defect Bi catalyst displays excellent performance for the paired-electrosynthesis of H2O2, delivering a remarkable cell Faradaic efficiency of 154.8% and an ultrahigh H2O2 production rate of 4.3 mmol h-1 cm-2. Experiments combined with theoretical analysis reveal the crucial role of oxygen vacancies in optimizing the adsorption of intermediates associated with the selective two-electron reaction pathways, thereby improving the activity and selectivity of the 2e- reaction processes at both electrodes. This work establishes a new paradigm for developing advanced electrocatalysts and designing novel paired-electrolysis systems for scalable and sustainable H2O2 electrosynthesis.

Harvesting high-performance electro-water oxidation and selective MB degradation through dual functional Gd2O3–La2O3 photo-electrocatalysts

Interestingly, catalytic oxygen evolution reaction (OER) in an alkaline medium with minimizing the overpotential is the most trustworthy electrocatalyst for the output of hydrogen energy from copious water electrochemical activity. Currently, amalgamated trivalent cations metal oxides have gained desirability as a low-cost anode electrocatalyst to replace noble metal-supported electrocatalysts for water oxidation and are also used for photo-degradation applications. In the present work, we have successfully synthesized Gd2O3 supported La2O3 composites via hydrothermal pathways for efficient OER and selective methylene blue (MB) degradation applications. XRD, UV–Vis DRS, FT-IR, XPS, SEM-EDX, HR-TEM, DLS, and BET analyzers confirmed the successful synthesis of photo-electrocatalysts. Gd2O3–La2O3 composites achieved 5.66 and 3.37-fold larger surface areas than La2O3 and Gd2O3, respectively. The results of the Gd2O3 supported La2O3 composite electrode demonstrated better OER performance under 1 M KOH, and it exhibited a lower Tafel slope and overpotential of 72 mV dec−1 and 310 mV at 10 mA cm−2. A chronoamperometry examination confirms that the fabricated Gd2O3–La2O3 electrode has good stability at a fixed potential of 1.540 V vs. RHE for water oxidation. Although the, Gd+3 inspired La2O3 electrode actively takes part in OER activity owing to its high Cdl value of 40.222 μF cm−2. The selective degradation of MB dye using the Gd2O3–La2O3 composite achieved an acceptable degradation efficiency of 84.80 % compared to other pollutants under UV-light irradiation for 120 min, and the specified pH condition is 9 for the degradation of MB dye, and it follows the first-order kinetics model. Notably, post-OER and photocatalytic results exhibited good stability and reusability characteristics. Therefore, the Gd2O3–La2O3 catalyst can be used for real-time water oxidation and MB dye removal from polluted water.

Self-driving photothermal anode electrocatalyst towards the robust OER for water electrolysis

The hydrogen production of water electrolysis is a potential technique route of clean energy exchange, but suffering from the sluggish oxygen evolution reaction (OER) owing to its four-electron step. In this work, we presented a significant improvement in the OER activity by photothermally triggering P-doped NiFe2O4 (NFO–P) electrocatalyst. As compared to the NiFe2O4 (NFO) catalyst, the excellent PEC performance of robust NFO–P is a result of more readliy generated active sites (Ni(III)), evidencing by the in-situ Raman spectra and polarization curves. With the near-infrared (λ = 808 nm) irradiation, the NFO–P surface temperature increases from 37 to 73 °C, and the NFO–P delivers a current density of 10 mA cm−2 at a pretty low overpotential of 191 mV (10 W/cm2), outperforms most OER catalysts including noble oxides. Photothermal enhancement in OER is attributed to photogenerated hot carriers and thermal activation. The thermal effect accelerates the kinetics, while with the assistance of the hot carrier, the rate-determining step (RDS) transforms from the O* to OOH* formation, reducing the activation energy. This study offers a thorough understanding of the combined contributions of hot carriers and thermal effects to the OER and also opens avenues for enhancing electrochemical efficiency and diminishing techno-economic costs in future applications.

Electronic-Structure Transformation of Platinum-Rich Nanowires as Efficient Electrocatalyst for Overall Water Splitting.

Platinum (Pt) has been widely used as cathodic electrocatalysts for the hydrogen evolution reaction (HER) but unfortunately neglected as an anodic electrocatalyst for the oxygen evolution reaction (OER) due to excessively strong bonding with oxygen species in water splitting electrolyzers. Herein we report that fine control over the electronic-structure and local-coordination environment of Pt-rich PtPbCu nanowires (NWs) by doping of iridium (Ir) lowers the overpotential of the OER and simultaneously suppresses the overoxidation of Pt in IrPtPbCu NWs during water electrolysis. In light of the one-dimensional morphology featured with atomically dispersed IrOx species and electronically modulated Pt-sites, the IrPtPbCu NWs exhibit an enhanced OER (175 mV at 10 mA cm-2) and HER (25 mV at 10 mA cm-2) electrocatalytic performance in acidic media and yield a high turnover frequency. For OER at the overpotential of 250 mV, the IrPtPbCu NWs show an enhanced mass activity of 1.51 A mg-1Pt+Ir (about 19 times higher) than Ir/C. For HER at the overpotential of 50 mV, NWs exhibit a remarkable mass activity of 1.35 A mg-1Pt+Ir, which is 2.6-fold relative to Pt/C. Experimental results and theoretical calculations corroborate that the doping of Ir in NWs has the capacity to suppress the formation of Ptx>4 derivates and ameliorate the adsorption free energy of reaction intermediates during the water electrolysis. This approach enabled the realization of a previously unobserved mechanism for anodic electrocatalysts.

Microwave initiated synthesis of carbon nanosphere from plastic and its application as anode electrocatalyst support in direct methanol fuel cell

The term plastisphere was coined to describe the human-made plastic environment, addressing the challenges of plastic waste. This study presents a rapid method using microwave susceptor catalysts (Co/Mo/Biochar, Ni/Mo/Biochar, Fe/Mo/Biochar) for the catalytic degradation of polystyrene into valuable carbon in microwave synthesizer. Using SEM, we found that active metal nanoparticles are uniformly distributed and the sizes of the active porous sites varied depending upon the catalyst used where the porous active sites of catalyst Co/Mo/biochar, Ni/Mo/biochar and Fe/Mo/biochar ranges between 300 nm and 700 nm, 2.21 μm and 4.05 μm, and 5 μm to larger pore size respectively. The microwave initiated catalytic synthesis process transforms uniform-sized polystyrene pellets into carbon nanospheres within 90 s. From XRD characterization, the broadened peaks at (002) plane resulted from the graphitic flakes' waving structure, confirming that the carbon nanospheres formed are graphitic in nature which is in agreement with results obtained from Raman spectroscopy. This study also explores polystyrene as an energy feedstock, utilizing Co/Mo/Biochar synthesized carbon nanospheres (CNS) which is mesoporous in nature with BET average surface area about 1428.3 m2/g as anode electro catalyst support for methanol oxidation in direct methanol fuel cells. The Pt Ru (1:1) supported on CNS catalyst exhibited higher electro catalytic activity compared to commercial PtRu/C, as indicated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS).

Synergistic Effect Enables the Dual-Metal Doped Cobalt Telluride Particles as Potential Electrocatalysts for Oxygen Evolution in Alkaline Electrolyte.

Cobalt (Co)-based materials have been widely investigated as hopeful noble-metal-free alternatives for the oxygen evolution reaction (OER) in alkaline electrolytes, which is crucial for generating hydrogen by water electrolysis. Herein, cobalt-based telluride particles with good electronic conductivity as anodic electrocatalysts were prepared under vacuum by the solid-state strategy, which display remarkable activities toward the OER. Nickel (Ni) and iron (Fe) codoped cobalt telluride (NiFe-CoTe) exhibits an overpotential of 321 mV to achieve a current density of 10 mA cm-2 and a Tafel slope of 51.8 mV dec-1, outperforming the performances of CoTe, CoTe2, and IrO2. According to the DFT calculation, the adsorbed hydroxyl-assisted adsorbate evolution mechanism was proposed for the OER process of NiFe-CoTe, which reveals the synergetic effect toward OER induced by codoping of the Ni and Fe atoms. This work proposes a rational strategy to prepare cobalt-based tellurides as efficient OER catalysts in alkaline electrolytes, providing a new strategy to prepare and regulate metal-based tellurides for catalysis and beyond.

Improving the electrocatalysts for conversion-type anodes of alkali-ion batteries

Improving the electrocatalysts for conversion-type anodes of alkali-ion batteries

Boosting the Electrolysis of Monosaccharide-Based Streams in an Anion-Exchange Membrane Cell.

A systematic study on the electrochemical reforming of monosaccharides (fructose, glucose, and xylose) using Pt-based anodic electrocatalysts is here presented for the first time to completely optimize the anodic catalyst and electrolyzer operating conditions. First, the electro-oxidation of each molecule was studied using a monometallic (Pt) and two bimetallic (PtNi and PtCo) anodic electrocatalysts supported on graphene nanoplatelets (GNPs). Tests in a three-electrode cell showed superior electrochemical activity and durability of PtNi/GNPs, especially at potentials higher than 1.2 V vs RHE, with the highest electrocatalytic activity in d-xylose electro-oxidation. Then, monometallic (Pt and Ni) and bimetallic electrocatalysts with different Pt:Ni mass ratios (1:1 and 2:1) were studied for d-xylose electro-oxidation, with the 2:1 mass ratio presenting the best results. This electrocatalyst was selected as the most suitable for scale-up to an anion-exchange membrane electrolyzer, where the optimal operating potential was determined. Additionally, stable operating conditions of the electrolyzer were achieved by cyclic H2 production and cathodic regeneration polarization steps. This led to suitable and reproducible H2 production rates throughout the production cycles for renewable hydrogen production from biomass-derived streams.