Non-Platinum metal oxide nano particles and nano clusters as oxygen reduction catalysts in fuel cells.

An attempt has been made in this study to prepare the oxygen electrodes containing low-scale particles of copper, nickel, cobalt and iron oxides and evaluate their catalytic activity for the oxygen reduction. 1:1 stoichiometric oxides (Copper and Nickel) and higher stoichimetric oxides (Cobalt and Iron) have been synthesized and their catalytic properties have been analyzed by electrochemical methods. The conductivity of the fabricated electrodes showed steady values even with change in temperature from the ambient (30 ± 20 C) to 700 C

Novel Nanofluids Based on Magnetite Nanoclusters and Investigation on Their Cluster Size-Dependent Thermal Conductivity

To probe the effect of particle size on thermal conductivity (<i>k</i>) enhancement in nanofluids, especially in a very large particle size range, we study the cluster size-dependent <i>k</i> in novel nanofluids containing magnetite (Fe₃O₄) nanoclusters. The Fe₃O₄ nanoclusters in the size range of 115 to 530 nm were synthesized by a facile and cost-effective solvothermal approach. The structural, surface, and magnetic characteristics of Fe₃O₄ nanoclusters were investigated by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Thermal conductivity studies in diethylene glycol (DEG)-based Fe₃O₄ cluster nanofluids showed an enhancement in <i>k</i> with an increase in nanocluster size. With a fixed volume fraction (ϕ) = 0.0193, the <i>k</i> enhancement was about 5.3% and 12.6%, respectively, for nanofluids having cluster size of 115 and 530 nm. The observed increase in nanofluid <i>k</i> with increase in cluster size being contrary to the microconvection hypothesis confirms the less prominent role of Brownian motion-induced microconvection on the <i>k</i> enhancements of nanofluids. The increase in nanofluid <i>k</i> with increase in cluster size is attributed to the growth of clusters into fractal-like aggregates in the suspensions which was confirmed by optical microscopy, dynamic light scattering (DLS), and atomic force microscopy (AFM) studies. Furthermore, the experimental <i>k</i> data fall within the upper and lower Maxwell bounds for homogeneous systems, confirming the classical nature of thermal conduction in nanofluids. The nanofluids developed in the present study are promising candidates for heat transfer applications because of their improved thermal conductivity and long-term stability. The present study can provide new insights for engineering efficient nanofluids containing nanoclusters with superior thermal conductivity for heat transfer applications

Is the H2 economy realizable in the foreseeable future? Part II: H2 storage, transportation, and distribution

The goal of the review series on the H2 economy is to highlight the current status, major issues, and opportunities associated with H2 production, storage, transportation, distribution and usage in various energy sectors. In particular, Part I discussed the various H2 (grey and green) production methods including the futuristic ones such as photoelectrochemical for small, medium, and large-scale applications. Part II of the H2 economy review identifies the developments and challenges in the areas of H2 storage, transportation and distribution with national and international initiatives in the field, all of which suggest a pathway for establishing greener H2 society in the near future. Currently, various methods, comprising physical and chemical routes are being explored with a focus on improving the H2 storage density, capacity, and reducing the cost. H2 transportation methods by road, through pipelines, and via ocean are pursued actively in expanding the market for large scale applications around the world. As of now, compressed H2 and its transportation by road is the most realistic option for the transportation sector. Peer reviewe

Is the H2 economy realizable in the foreseeable future? Part I: H2 production methods

The efforts on energy system decarbonization and improved sustainable energy efficiency in developed countries led energy enthusiasts to explore alternative highly effective pathways in accomplishing these goals. Specifically, the transition from hydrocarbon to H2 economy using fuel cells and H2 technologies is a sustainable and favorable approach forward in meeting stationary, transportation, industrial, residential, and commercial sectors. This review in three Parts brings out the capability of H2 for enabling an energy revolution through much-needed flexibility in renewable energy resources. The review identifies the developments and challenges within the H2 generation, storage, transportation, distribution, and usage - as well as applications along with national and international initiatives in the field, all of which suggest a pathway for a greener H2 society. The review also highlights the opportunities and challenges in major energy sectors for H2 technologies. Part I of the series highlights the importance of H2 economy and initiatives from various agencies, and presents several H2 generation methods.Peer reviewe

Is the H2 economy realizable in the foreseeable future? Part II: H2 storage, transportation, and distribution

The goal of the review series on the H2 economy is to highlight the current status, major issues, and opportunities associated with H2 production, storage, transportation, distribution and usage in various energy sectors. In particular, Part I discussed the various H2 (grey and green) production methods including the futuristic ones such as photoelectrochemical for small, medium, and large-scale applications. Part II of the H2 economy review identifies the developments and challenges in the areas of H2 storage, transportation and distribution with national and international initiatives in the field, all of which suggest a pathway for establishing greener H2 society in the near future. Currently, various methods, comprising physical and chemical routes are being explored with a focus on improving the H2 storage density, capacity, and reducing the cost. H2 transportation methods by road, through pipelines, and via ocean are pursued actively in expanding the market for large scale applications around the world. As of now, compressed H2 and its transportation by road is the most realistic option for the transportation sector.Peer reviewe