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The oxygen evolution reaction (OER) holds pivotal importance in sustainable energy conversion, as it forms the critical half-reaction in various electrochemical processes, including water splitting for hydrogen production and rechargeable metal-air batteries. Here, a CoFe2O4@Co3O4 nano-composite was synthesized using a facile hydrothermal process and deposited onto the surface of nickel foam through electrophoresis. Characterization using XRD, Raman spectroscopy, and XPS confirmed the successful synthesis of the composite, exhibiting characteristic peaks of both Co3O4 and CoFe2O4. The nano-composite exhibited a more amorphous phase than pure oxides, benefiting electrocatalytic activity. Scanning and transmission electron microscopy highlighted the composite's morphological characteristics, showcasing a Co3O4 island distribution on the CoFe2O4 surface. Electrochemical evaluations revealed the superior oxygen evolution reaction (OER) performance of CoFe2O4@Co3O4, with low overpotentials, faster kinetics, and enhanced stability compared to pure oxides and the benchmark RuO2 catalyst. A comprehensive analysis was carried out to investigate the dynamic behavior during electrocatalytic oxygen evolution reaction. This study unveils the intricate charge and electron transfer mechanisms between cobalt and iron atoms, providing insights into their collaborative role throughout the OER process. [ABSTRACT FROM AUTHOR]

This paper focuses on the analysis of the COVID-19 effects on passenger shipping in Danish waters as an example and aims to analyse the differences in passenger vessel activities and emissions before and after the COVID-19 outbreak. Two sets of Automatic Identification System (AIS) data for the passenger ships sailing in Danish waters associated with the whole year respectively for 2020 and 2019 are used for a comprehensive evaluation of the passenger shipping activities in the region by means of the analysis of variance and bottom-up emission models. A comparison of those results based on the two datasets shows that the COVID-19 pandemic has a major impact on cruise ships, with a significant reduction in the number of ships, average speed, and average draught. In contrast, the pandemic has a smaller impact on ferry-pax only and ferry-ro pax vessels. The effects can also be seen from the fact that, after the COVID-19 outbreak, SOx emissions from cruise ships, ferry-pax only and ferry-ro pax vessels were reduced by 50.71%, 0.51% and 0.82%, respectively. This investigation provides an important reference for policy makers in the marine environment sector. [ABSTRACT FROM AUTHOR]

Solar air collectors are commonly used in a variety of domestic and industrial fields. The simple design and low maintenance cost are among their advantages compared to other solar collectors. However, the main challenge of this type of collector is the low heat transfer coefficient. In this work, the effect of different designs of the absorber plate (waved and V corrugated modification) on the thermal performances, the heat exchange effectiveness and the air outlet temperature of a Double-Pass Parallel-Flow air solar collector was investigated under the solar radiation of MarrakechMorocco in a clear day and for three different mass flows rates (0.008 kg s-1, 0.012 kg s-1 and 0.016 kg s -1). The numerical study was done using Computational Fluid Dynamics (CFD) by the mean of ANSYS Fluent 16.0. The obtained results showed that the V corrugated modification is the most efficient one with efficiency equal to 76.92 % and 87.97 % under the lowest and highest mass flow, respectively. [ABSTRACT FROM AUTHOR]