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Vanadium redox flow batteries (VRFBs) are a promising solution for integrating intermittent renewable energy sources into the existing power grid. However, enhancing the electrochemical performance of VRFBs is critical for their widespread adoption in grid-scale energy storage. This study investigates the impact of adding a porous binder to a carbon-cloth electrode, with a focus on optimizing thermal activation conditions. The electrochemical performance of the binder-coated electrodes compared to uncoated electrodes is evaluated through electrochemical impedance spectroscopy, polarization curve measurements, and charge-discharge cycling. The surface morphology and structural integrity of the binder-coated electrodes at each activation stage are examined using various material characterization techniques to assess the effects of thermal activation. The results are benchmarked against the experiments using non-coated electrodes to determine the performance improvements offered by the binder coating. Notably, the study reveals that binder-coated electrodes exhibit significantly lower resistance and improved efficiency compared to their uncoated counterparts, with optimal activation conditions enhancing performance metrics crucial for VRFB applications. These findings provide valuable insights for further optimizing electrode design and activation strategies, advancing the development of more efficient VRFB systems for large-scale energy storage.

This contribution reports the discovery and analysis of a p-block Sn-based catalyst for the electroreduction of molecular oxygen in acidic conditions at fuel cell cathodes; the catalyst is free of platinum-group metals and contains single-metal-atom actives sites coordinated by nitrogen. The prepared SnNC catalysts meet and exceed state-of-the-art FeNC catalysts in terms of intrinsic catalytic turn-over frequency and hydrogen–air fuel cell power density. The SnNC-NH3catalysts displayed a 40–50% higher current density than FeNC-NH3at cell voltages below 0.7?V. Additional benefits include a highly favourable selectivity for the four-electron reduction pathway and a Fenton-inactive character of Sn. A range of analytical techniques combined with density functional theory calculations indicate that stannic Sn(iv)Nxsingle-metal sites with moderate oxygen chemisorption properties and low pyridinic N coordination numbers act as catalytically active moieties. The superior proton-exchange membrane fuel cell performance of SnNC cathode catalysts under realistic, hydrogen–air fuel cell conditions, particularly after NH3activation treatment, makes them a promising alternative to today’s state-of-the-art Fe-based catalysts.

While improved activity was recently reported for bimetallic iron-metal-nitrogen-carbon (FeMNC) catalysts for the oxygen reduction reaction (ORR) in acid medium, the nature of active sites and interactions between the two metals are poorly understood. Here, FeSnNC and FeCoNC catalysts were structurally and catalytically compared to their parent FeNC and SnNC catalysts. While CO cryo-chemisorption revealed a twice lower site density of M-Nxsites for FeSnNC and FeCoNC relative to FeNC and SnNC, the mass activity of both bimetallic catalysts is 50–100% higher than that of FeNC due to a larger turnover frequency in the bimetallic catalysts. Electron microscopy and X-ray absorption spectroscopy identified the coexistence of Fe-Nxand Sn-Nxor Co-Nxsites, while no evidence was found for binuclear Fe-M-Nxsites. 57Fe Mössbauer spectroscopy revealed that the bimetallic catalysts feature a higher D1/D2 ratio of the spectral signatures assigned to two distinct Fe-Nxsites, relative to the FeNC parent catalyst. Thus, the addition of the secondary metal favored the formation of D1 sites, associated with the higher turnover frequency.

In the present study, highly porous 3D-Graphene nanosheets (3D-GNS) were synthesized using the Sacrificial Support Method (SSM) and utilized as a support for palladium (Pd) nanoparticles. The Pd nanoparticles were deposited using the original Pd-precursor based Soft Alcohol Reduction Method (SARM) with different alcohols. The obtained materials were comprehensively characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning transmission electron microscopy (SEM). Chemically reduced Pd/3D-GNS catalysts were then studied for the electrochemical oxidation of ethanol and methanol in alkaline media. Our study shows that combination of SSM and SARM-EtOH fabrication process allowed obtaining materials with a smaller particle size distribution and a higher surface area (yielding better utilization of Pd), as well as the highest electrochemical activity and durability, with a peak current density of over 1100 A/gPd for ethanol electrooxidation.

A series of CuCo2O4 catalysts were synthesized by pore forming, sol-gel, spray pyrolysis and sacrificial support methods. Catalysts were characterized by XRD, SEM, XPS and BET techniques. The electrochemical activity for the oxygen reduction and oxygen evolution reactions (ORR and OER) was evaluated in alkaline media by RRDE. Density Functional Theory was used to identify two different types of active sites responsible for ORR/OER activity of CuCo2O4 and it was found that CuCo2O4 can activate the O-O bond by binding molecular oxygen in bridging positions between Co or Co and Cu atoms. It was found that the sacrificial support method (SSM) catalyst has the highest performance in both ORR and OER and has the highest content of phase-pure CuCo2O4. It was shown that the presence of CuO significantly decreases the activity in oxygen reduction and oxygen evolution reactions. The half-wave potential (E1/2) of CuCo2O4-SSM was found as 0.8 V, making this material a state-of-the-art, unsupported oxide catalyst.

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To investigate the contribution of the ZnO supports in PdZn/ZnO catalysts used for methanol steam re-forming (MSR), we have investigated methanol steam re-forming on two different ZnO powder samples. The powder samples included a commercial powder with both polar and nonpolar surfaces exposed, and a plate-like sample preferentially exposing the polar ZnO(001)/ (001̅) surfaces. ZnO was found to be active and selective for MSR, with the polar surfaces being most active, but the activation energy for reaction (∼100 kJ/mol) was much larger than on unsupported PdZn(∼50 kJ/mol) or PdZn/ZnO. The experimental findings are supported by DFT calculations on key elementary steps and reaction intermediates on the ZnO(001) surface. We conclude that the contribution of the ZnO support to the MSR activity PdZn/ZnO catalyst system may not be very significant.

A series of CuCo2O4catalysts were synthesized by pore forming, sol-gel, spray pyrolysis and sacrificial support methods. Catalysts were characterized by XRD, SEM, XPS and BET techniques. The electrochemical activity for the oxygen reduction and oxygen evolution reactions (ORR and OER) was evaluated in alkaline media by RRDE. Density Functional Theory was used to identify two different types of active sites responsible for ORR/OER activity of CuCo2O4and it was found that CuCo2O4can activate the O-O bond by binding molecular oxygen in bridging positions between Co or Co and Cu atoms. It was found that the sacrificial support method (SSM) catalyst has the highest performance in both ORR and OER and has the highest content of phase-pure CuCo2O4. It was shown that the presence of CuO significantly decreases the activity in oxygen reduction and oxygen evolution reactions. The half-wave potential (E1/2) of CuCo2O4-SSM was found as 0.8 V, making this material a state-of-the-art, unsupported oxide catalyst.