kinetics of ORR is around five orders of magnitude slower than that of HOR, thereby requiring a much higher Pt loading in the cathode along with more active and durable ORR electrocatalysts than pure Pt catalysts. [1] This requirement presents challenges for the development of advanced cathode catalysts with lower cost, higher activity and higher durability than Pt. Meanwhile, traditional alkaline fuel cells (AFCs) working on concentrated 30−45% KOH electrolytes gained little attention for decades mainly due to their high sensitivity to atmospheric CO 2 . [2,3] The OH − ions in the electrolyte react with CO 2 and form K 2 CO 3 , which can precipitate out as solid crystals, blocking pores in the electrode and gas diffusion layer. In addition, the consumption of OH − reduces the conductivity of the electrolyte. This issue is addressed by replacing KOH solution with a solid anion exchange membrane (AEM) without mobile cations. An AMFC offers several important advantages over PEMFCs, including: 1) low dissolution rates of catalysts, allowing the use of less expensive Pt-free electrocatalysts; 2) wide selections of materials and components that are stable at high pH; and 3) inexpensive solid electrolytes that do not need fluorinated ionomers. Despite their promise, AMFCs are still in the early development stage and have not been systematically investigated due to the lack of highly conductive and durable AEMs. The recent development of highly conductive The rapid progress of proton exchange membrane fuel cells (PEMFCs) and alkaline exchange membrane fuel cells (AMFCs) has boosted the hydrogen economy concept via diverse energy applications in the past decades. For a holistic understanding of the development status of PEMFCs and AMFCs, recent advancements in electrocatalyst design and catalyst layer optimization, along with cell performance in terms of activity and durability in PEMFCs and AMFCs, are summarized here. The activity, stability, and fuel cell performance of different types of electrocatalysts for both oxygen reduction reaction and hydrogen oxidation reaction are discussed and compared. Research directions on the further development of active, stable, and low-cost electrocatalysts to meet the ultimate commercialization of PEMFCs and AMFCs are also discussed.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202006292.

No abstract

No abstract

Ammonia electro-oxidation is an extremely significant reaction with regards to the nitrogen cycle, hydrogen economy, and wastewater remediation. The design of efficient electrocatalysts for use in the ammonia electro-oxidation reaction (AOR) requires comprehensive understanding of the mechanism and intermediates involved. In this study, aggregation-induced emission (AIE), a robust fluorescence sensing platform, is employed for the sensitive and qualitative detection of hydrazine (N 2 H 4 ), one of the important intermediates during the AOR. Here, we successfully identified N 2 H 4 as a main intermediate during the AOR on the model Pt/C electrocatalyst using 4-(1,2,2-triphenylvinyl)benzaldehyde (TPE-CHO), an aggregation-induced emission luminogen (AIEgen). We propose the AOR mechanism for Pt with N 2 H 4 being formed during the dimerization process (NH 2 coupling) within the framework of the Gerischer and Mauerer mechanism. The unique chemodosimeter approach demonstrated in this study opens a novel pathway for understanding electrochemical reactions in depth.

No abstract

In the current study zidovudine loaded PLGA nanoparticles were prepared, coated and further investigated for its effectiveness in brain targeting. IR and DSC studies were performed to determine the interaction between excipients used and to find out the nature of drug in the formulation. Formulations were prepared by adopting 2(3) factorial designs to evaluate the effects of process and formulation variables. The prepared formulations were subjected for in vitro and in vivo evaluations. In vitro evaluations showed particle size below 100 nm, entrapment efficiency of formulations ranges of 28-57%, process yield of 60-76% was achieved and drug release for the formulations were in the range of 50-85%. The drug release from the formulations was found to follow Higuchi release pattern, n-value obtained after Korsemeyer plot was in the range of 0.56-0.78. In vivo evaluations were performed in mice after intraperitoneal administration of zidovudine drug solution, uncoated and coated formulation. Formulation when coated with Tween 80 achieved a higher concentration in the brain than that of the drug in solution and of the uncoated formulation. Stability studies indicated that there was no degradation of the drug in the formulation after 90 days of preparation when stored in refrigerated condition.

No abstract

No abstract