The storage system developed in this experimental work is a prototype aimed at testing the feasibility of the HyCARE European project objective: to collect and provide renewable energy using hydrogen as an energy carrier, with metal hydrides (MH) for hydrogen storage and phase change materials (PCM) for thermal storage and management. This concept is validated by designing and testing an integrated system that couples a PCM module with an MH tank capable of storing up to 0.64 kg of H2, i.e., about 31 kg H2/m3. The solution of a PCM-based thermal buffering system for the MH absorption/desorption heat of reaction minimizes external energy reliance. By monitoring hydrogen pressure and flow, temperature profiles, and thermal vector fluid (TVF) flow rates during the experiments, the optimal starting conditions and requirements for gas and TVF flows are assessed to reduce external power inputs. From the results, it can be concluded that, with these settings, the PCM can store the heat generated/needed by the MH tank, and the external power supply is required only to compensate for heat losses, achieving a 35–41% net energy saving.
Here we demonstrate a simple and versatile controlled sol-gel synthesis (in the presence of palmitic acid (Palm) as a structure-directing agent) in combination with hydrothermal treatment followed by calcination at 500°C for 4 h to produce new thermally stable, uniform non-aggregated mesoporous hierarchical nanocrystalline cloudberry-like TiO2 microparticles (12-15 μm) possessing four levels of organization of structural elements. Prepared microparticles are formed by aggregation and agglomeration of anatase crystallites of ca. 10 nm in size and reveal superior photocatalytic activity in gas phase ethanol oxidation (more than 4-fold higher compared to commercial Evonik P25). We show that fine tuning of synthesis conditions, the use of small amounts of surfactant dodecyldimethylethylammonium bromide (DDMEABr) and/or La3+ ions, citric acid additives lead to drastical changes in the morphology of the resulting titania product. Numerous new complex shapes of hierarchical TiO2 micro/nanoarchitectures were obtained on various metallic surfaces by facile applying of uncalcined TiO2 products at room temperature.
We report the nickel nanostructures electrodeposited with different morphologies to cover the nickel foam and copper oxide nanowire modified substrates. Our approach using different pulse-electrodeposition showed successful bottom-up growth of nanostructured materials ranging from dense rhombic pyramids to interlaced three-dimensional (3D) nanorod networks. The results revealed that the electrode comprised of electrodeposited nanocrystalline Ni films/CuO nanowires/copper foam featuring a 3D morphology provided a higher electrochemically active surface area, rapid redox kinetics, and highly reduced charge-transfer resistance (2.817 Ω). The quasi-solid-state Ni–Zn battery assembly using the 3D Ni electrode exhibited a significant performance over different charge and discharge current rates with particularly achieved maximum capacity of 110.9 mAh·g−1 at 5 mA cm−2. This represents an enhancement of more than tenfold compared with Ni–Zn electrodes based on nanocrystalline nickel films. Transport of ions and electrons and multi-electron Ni redox with the O–O* intermediates with a defect-rich nanostructure from the pulsed reverse current (PRC) was the main reason for the improvement of performance. We are sure that the present work features a 3D design for high-kinetic Ni–Zn batteries.
Electrocatalysis at the atomic level signifies a transformative method to sustainable energy conversion by permitting near-complete metal utilization and precise control over the coordination environment; yet, single atomic catalysts (SACs) are restricted by single active site scaling relationships, which limit their capacity to orchestrate complex reaction pathways involving multiple electron-transfer steps. To resolve these thermodynamic and kinetic states, cooperative electrocatalysts, integrating heteronuclear single-atom pairs, single-atom/cluster (SA-cluster) assemblies, and single-atom/nanoparticle (SA-NP) heterointerfaces, have appeared as an advanced frontier. In this work, we report recent advances in multisite synergistic electrocatalysis, emphasizing how cooperative active centers can overcome the intrinsic restrictions of isolated catalytic sites, highlight state-of-the-art real spectroscopic methods, and recent characterization techniques that enable the determination of atomic distributions, oxidation states, and local coordination environments. To confirm the structure, first-principles approaches are discussed for clarifying potential-dependent electronic-structure evolution, d-orbital splitting, work-function matching, and charge redistribution at heterogeneous interfaces. The cooperative catalytic behavior is then studied across key energy-conversion reactions, including the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, carbon dioxide reduction reaction, and nitrogen reduction reaction, with emphasis on their ability to alleviate conventional scaling limitations. Finally, this review classifies general design principles and remarkably challenges for the rational development of next-generation multisite electrocatalysts.
