Electrochemical reduction of gaseous feeds such as CO2, CO, and N2 holds promise for sustainable energy and chemical production. Practical application of this technology is impeded by slow mass transport of the sparingly soluble gases to conventional planar electrodes. Gas diffusion electrodes (GDEs) maintain a high gas concentration in the vicinity of the catalyst and improve mass transport, thereby resulting in current densities higher by orders of magnitude. However, gaseous feeds cause changes to the GDE environment, and specific features are required to efficiently tune the product selectivity and improve reaction stability. Herein, with a comprehensive review of the challenges and advances in GDE development for various electrocatalytic reactions, we intend to complement the body of material-focused reviews. This review outlines GDE fundamentals and highlights key advantages of GDE over conventional electrodes. Through critical discussion about steps in GDE fabrication, and specific shortcomings and remedial strategies for various electrochemical applications, this review discusses connections, unique design criteria, and potential opportunities for gas-fed reactions and desired products. Finally, priorities for future studies are suggested, to support the advancement and scale-up of GDE-based electrochemical technologies.

Gas diffusion electrodes (GDEs) for electrochemical reduction of carbon dioxide, carbon monoxide, and dinitrogen to value-added products: a review

Recently, mechanical micro-milling is one of the most promising micro-manufacturing processes for productive and accurate complex-feature generation in various materials including metals, ceramics, polymers and composites. The micro-milling technology is widely adapted already in many high-tech industrial sectors; however, its reliability and predictability require further developments. In this paper, micro-milling related recent results and developments are reviewed and discussed including micro-chip removal and micro-burr formation mechanisms, cutting forces, cutting temperature, vibrations, surface roughness, cutting fluids, workpiece materials, process monitoring, micro-tools and coatings, and process-modelling. Finally, possible future trends and research directions are highlighted in the micro-milling and micro-machining areas.

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A review on micro-milling: recent advances and future trends

Advancing green energy solution with the impetus of COVID-19 pandemic

The study of the electrochemical catalyst conversion of renewable electricity and carbon oxides into chemical fuels attracts a great deal of attention by different researchers. The main role of this process is in mitigating the worldwide energy crisis through a closed technological carbon cycle, where chemical fuels, such as hydrogen, are stored and reconverted to electricity via electrochemical reaction processes in fuel cells. The scientific community focuses its efforts on the development of high-performance polymeric membranes together with nanomaterials with high catalytic activity and stability in order to reduce the platinum group metal applied as a cathode to build stacks of proton exchange membrane fuel cells (PEMFCs) to work at low and moderate temperatures. The design of new conductive membranes and nanoparticles (NPs) whose morphology directly affects their catalytic properties is of utmost importance. Nanoparticle morphologies, like cubes, octahedrons, icosahedrons, bipyramids, plates, and polyhedrons, among others, are widely studied for catalysis applications. The recent progress around the high catalytic activity has focused on the stabilizing agents and their potential impact on nanomaterial synthesis to induce changes in the morphology of NPs.

Proton Exchange Membrane Fuel Cells (PEMFCs): Advances and Challenges

An overview of proton exchange membranes for fuel cells: Materials and manufacturing

Energy storage and conversion is a very important link between the steps of energy production and energy consumption. Traditional fossil fuels are a natural and unsustainable energy storage medium with limited reserves and notorious pollution problems, therefore demanding a better choice to store and utilize the green and renewable energies in the future. Energy and environmental problems require a clean and efficient way of using the fuels. Fuel cell functions to efficiently convert oxidant and chemical energy accumulated in the fuel directly into DC electric, with the by-products of heat and water. Fuel cells, which are known as effective electrochemical converters, and electricity generation technology has gained attention due to the need for clean energy, the limitation of fossil fuel resources and the capability of a fuel cell to generate electricity without involving any moving mechanical part. The fuel cell technologies that received high interest for commercialization are polymer electrolyte membrane fuel cells (PEMFCs), solid oxide fuel cells (SOFCs), and direct methanol fuel cells (DMFCs). The optimum efficiency for the fuel cell is not bound by the principle of Carnot cycle compared to other traditional power machines that are generally based on thermal cycles such as gas turbines, steam turbines and internal combustion engines. However, the fuel cell applications have been restrained by the high cost needed to commercialize them. Researchers currently focus on the discovery of different materials and manufacturing methods to enhance fuel cell performance and simplify components of fuel cells. Fuel cell systems’ designs are utilized to reduce the costs of the membrane and improve cell efficiency, durability and reliability, allowing them to compete with the traditional combustion engine. In this review, we primarily analyze recent developments in fuel cells technologies and up-to-date modeling for PEMFCs, SOFCs and DMFCs.

https://www.mdpi.com/2077-0375/10/5/99/pdf

New Perspectives on Fuel Cell Technology: A Brief Review

Effect of degradation by temperature onto nitrile rubber elastomer mechanical properties

Ball end milling process is one of the high-precision processes in fabricating spline and curve feature in manufactured components and parts. However, due to its complex geometrical feature, it is suggested to utilize expensive high-end tools to maintain its output accuracy during production due to its limited tool life. However, to utilize downscale tools, an online monitoring system is proposed as a method in observing machining process in real time and preventive or diversion action can be taken. The paper is going to discuss on the modelling of analog to fuzzy inference system during the ball end milling process, as a motivation on the application of artificial intelligence into manufacturing sector. In current stage of the study, ideal ball end-milling cutting force output signal is estimated through finite-element simulation and analog to fuzzy inference system is modelled. Parameters such as cutting speed, feed rate and depth of cut are analyzed and it is expected that this method will optimize the application of end milling tool especially high precision micro ball end mill during the machining processes.

Modelling of Fuzzy Inference System for Micro Milling—A Preliminary Study Through FEM

Viscosity is one of the factors affecting the performance of the centrifugal pump. A centrifugal pump is a device that used driven motor called impeller to move fluid by rotational energy. This thesis is about the analysis of the performance of the centrifugal pump when transferring viscous liquids. For this project, the objective is to design and fabricate a device that can pump liquid with various viscosity using centrifugal pump. The liquids used in the experiment are comprised of a mixture of detergent and water with different ratio to alter the viscosity. The viscosity is being identified by the usage of Zahn Cup Method with the temperature kept constant at 26 °C throughout the experiment. The performance of the centrifugal pump is being investigated by four parameters which is the flowrate, Total Dynamic Head (TDH), power and efficiency. The performance of the centrifugal pump can be accessed by altering the pump shaft speed in order to get various reading for the flow rate. In order to alter the pump shaft speed, the usage of motor with Variable Frequency Drive (VFD) is implemented. The values for the flowrate and pump shaft power are measured by flowmeter and Variable Frequency Drive (VFD). The Total Dynamic Head (TDH), hydraulic power and pump efficiency is calculated based on the reading of the flowmeter and pump shaft power displayed at Variable Frequency Drive (VFD). At the end of this project, the pump performance while pumping different viscous liquids at different flowrates is being identified.

/pdf/study-on-custom-centrifugal-pump-performance-in-supplying-3ibkv88zdv.pdf

Study on custom centrifugal pump performance in supplying food based high viscos liquid

The primary goal of this work is to investigate the performance of micro mill tools in terms of tool wear, average surface roughness, and chip size when machining aluminium alloy, as well as to evaluate the effect of cutting fluid application, using a 0.9 mm tungsten carbide (WC) tool with two flutes. This is because it is recognized that one of the essential factors in the micro-cutting process is the micro-cutting tool itself. The tool failure or wear affects the cost, average surface roughness, functionality, and the quality of the finished product greatly. The research is conducted under different cutting conditions with a varying feed rate of 0.001mm/tooth to 0.005mm/tooth and a cutting speed of 3.142m/min to 9.425m/min using a side milling process where the side flank face wear progression of the tool is measured. Then, the average surface roughness and chip size data are collected using a 3D laser measurement microscope. Based on the results, there is a similar tool wear trend in the micro-cutting process with the conventional methods. The results show that the use of cutting fluid has a significant impact on the quality of machined parts, both in terms of burr formation and machined surface quality. The relative size of the burrs formed is much larger than in macro machining operations, depending on the cutting conditions. Tool life and surface finish are impacted by built-up edges on cutting tools. The premature tool failure of the dry condition micro-cutting process is often focused on the entrance of the work-piece. Other than that, it is found that there are some instances where the average surface rough-ness decreases abruptly when it is reaching the fracture zone which is caused by the geometrical effect from the worn edge of the tool. This could be applied in the future design of the micro tool suitable for high-speed machining in dry conditions. It is also concluded that an appropriate selection of machining conditions has the potential to reduce tool wear rate and encourages longer tool life. 

Mohd Nizar Mhd Razali

Papers

New Perspectives on Fuel Cell Technology: A Brief Review

Effect of degradation by temperature onto nitrile rubber elastomer mechanical properties

Modelling of Fuzzy Inference System for Micro Milling—A Preliminary Study Through FEM

Study on custom centrifugal pump performance in supplying food based high viscos liquid

Micromilling performance analysis – cold air assisted aluminium machining behaviour observation