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As a step toward developing robust and highly active electrocatalysts for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), we have developed a polydopamine-derived iron-doped hollow carbon nanorod (FeHCNR). It exhibits high electrocatalytic activity toward the HER in acidic media with an overpotential of 29.4 mV at the current density of 50 mA cm–2. The catalyst also displays efficient activity for the ORR in acidic media with a high onset potential of 0.97 V. To demonstrate the practical feasibility of the HER characteristics, we designed a new type of Zn–H2hybrid battery for the simultaneous generation of hydrogen and electricity by asymmetric electrolysis with the acid catholyte and alkaline anolyte. The system displayed an open-circuit voltage of 1.28 V along with good stability compared to that of the one built using the commercial Pt/C catalyst. This device could generate H2gas with a Faradaic efficiency of 97% along with the generation of electricity. Moreover, the outstanding ORR activity of the FeHCNR could be validated by demonstrating an asymmetric-electrolyte Zn–air battery by employing the catalyst as the cathode, which provided an open-circuit voltage of 2.15 V and a power density of 69 mW cm–2with the contribution of the electrochemical neutralization energy along with Zn oxidation. Thus, the FeHCNR could perform well toward the HER and ORR during the system-level demonstrations, and this advantage is mainly credited to the hollow nanorod structure of the catalyst, which provides better exposure of the active sites along the outer and inner walls of the system to facilitate the concerned reactions. The open-tube cavity structure of the FeHCNR is supportive for the simultaneous diffusion of the electrolyte and reactants along with more facile dissipation of the products.

Novel methods for the synthesis of metal and alloy nanoparticles as well as their organized structures have been of much interest in nanoscience in recent years. In fact, the size-selective synthesis of nanoparticles below 5 nm is still of significant importance due to their high surface energy and reactivity. Herein, we report a simple, one-step, solid-state approach to synthesize Au nanoparticles of different sizes and shapes ranging from small nanoparticles of 3 nm to larger polyhedra of about 200 nm, by microwave-assisted reaction of a pasty mass formed by mixing Glucose powder with an aqueous solution of HAuCl4. It is shown that very small Au nanoparticles with an average particle size of 4.52 nm can be selectively speciated from the larger ones into an ethanolic dispersion of 1-decanethiol, which gets transformed into hexagonally close-packed two-dimensional superlattices upon drying-induced self-assembly.

AbstractThe green-H2production through water electrolysis from renewable energies is vital in the context of developing a sustainable and cost-effective methodology. Anion exchange membrane water electrolyzer (AEMWE) is considered as a promising energy conversion device, which can be an alternative to fossil fuel-based energyplatforms. AEMWE can employ inexpensive nonprecious metal catalysts and current collectors, which is preferable forpractical applications of this technology. Membrane electrode assemblies (MEAs) for AEMWE plays a significant role forthe hydrogen production efficiency. Thus, understanding the MEA components, operation, and performance is critical forthe development of prominent materials for the AEMWE. In this review, we highlight the performances of the MEAs andtheir components, such as the AEMs and catalysts with a broad discussion of the progress with current status. Additionally,we also have put forward our assessment to lead the way for future research, to commercialize AEMWE as a provenalternative for the cost-effective production of high-purity hydrogen.