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Digital games are one of the potential pedagogical approaches within STEM teaching and learning. The main idea behind using digital games in STEM contexts is to enhance the children’s conceptual understanding and to increase their interest in STEM. The interest in STEM is still an unsolved global issue. Most studies looking into digital games show there to be positive implications when it comes to STEM learning. This gap and the uncorrelated scenario from both the theoretical and practical perspectives need to both be solved. Here we conceptualise the usefulness of STEM digital games for stimulating an interest in STEM, particularly among children from a design perspective. The previous studies are the main qualitative sources for the interpretation of the main argument in this paper. As result, digital games have a strong empirically supportive foundational basis that acts as a medium to stimulate interest. To achieve this, STEM digital games should be designed to be of better quality. Good STEM digital games will contribute to better STEM learning outcomes and meaningful gaming experiences that can contribute to the interest in STEM. This study proposes a comprehensive framework to understand the purpose of the design and development of STEM digital games. https://doi.org/10.26803/ijlter.20.10.13

This paper focused on the parametric investigation and optimization of passive direct ethanol alkaline fuel cells (DEAFCs). A mathematical model was developed to simulate cell performance behaviour with variations in the ethanol feed concentration, the alkaline feed concentration and the operating temperature. In addition, the crossover ethanol behaviour was examined for different operating temperatures and ethanol feed concentrations. The mathematical model was solved in Matlab Environment. The simulation results showed that the ethanol and alkaline feed concentration ratio was the key parameter affecting the cell performance. Although higher alkaline addition yielded better performance, it was not favourable for prolonged applications due to practical limitations, such as corrosion, electrode destruction and catalyst decomposition. The ethanol crossover effect was greatly affected by the operating temperature and the ethanol concentration. Higher operating temperatures and ethanol concentrations significantly increased the crossover rate and reduced the cell performance. Thus, with all of the limitations and constraints, the suggested conditions for adequate performance of passive DEAFCs systems are 4 M ethanol and 4 M OH– at T = 30 °C.

The world has relied on fossil fuel energy for a long time, producing many adverse effects. Long-term fossil fuel dependency has increased carbon emissions and accelerated climate change. In addition, fossil fuels are also depleting and will soon be very costly. Moreover, the expensive national electricity grid has yet to reach rural areas and will be cut off in inundation areas. As such, alternative and carbon-free hydrogen fuel cell energy is highly recommended as it solves these problems. The reviews find that (i) compared to renewable energy such as solar, biomass, and hydropower, a fuel cell does not require expensive transmission through an energy grid and is carbon-free, and hence, it is a faster agent to decelerate climate change; (ii) fuel cell technologies have reached an optimum level due to the high-efficiency production of energy, and they are environmentally friendly; (iii) the absence of a policy on hydrogen fuel cells will hinder investment from private companies as they are not adequately regulated. It is thus recommended that countries embarking on hydrogen fuel cell development have a specific policy in place to allow the government to fund and regulate hydrogen fuel cells in the energy generation mix. This is essential as it provides the basis for alternative energy governance, development, and management of a country.

A cell network consists of a combination of fuel cells to achieve the targeted power consumption for a specific application. The main objective of this study is to design and optimise direct methanol fuel cell (DMFC) via cell integrated network model targeted for small portable application, such as cell phones and tablets. The target current and voltage was 1400 mA and 3.7 V, respectively, for a 5.18 W of cell network power. The optimisation was performed using 16 cells that were arranged in series with a voltage output of 3.781 V and a current of 1400 mA. The overall active area for the cell network was 128 cm2, and the cost of 1 set of cell networks is USD 1400.

UNSTRUCTURED In the modern age, digital games are widely used as informal media for Science, Technology, Engineering, and Mathematics (STEM) education and medical therapy for game-based learning. Digital games provide learners with a graphical system of interaction that enhances scientific concepts within an enjoyable environment. The vastly increasing number of digital games produced in the market affects the quality of STEM digital games while requiring multidisciplinary expertise. This paper proposes a framework for STEM digital game-based learning encompassing input-process-output stages. Several studies from the early 2000s onward were reviewed to discuss and present a new perspective on a framework for the design and development of digital games, particularly for STEM. This proposed framework consists of digital game development as input, experience as a process, and constructs as output. This simple and precise framework will generate a universal product for various types of learners. It can thus be used as a guideline for game designers, developers, and experts to develop STEM digital games and achieve better learning outcomes.

In the modern age, digital games are widely used as informal media for Science, Technology, Engineering, and Mathematics (STEM) education and medical therapy for game-based learning. Digital games provide learners with a graphical system of interaction that enhances scientific concepts within an enjoyable environment. The vastly increasing number of digital games produced in the market affects the quality of STEM digital games while requiring multidisciplinary expertise. This paper proposes a framework for STEM digital game-based learning encompassing input-process-output stages. Several studies from the early 2000s onward were reviewed to discuss and present a new perspective on a framework for the design and development of digital games, particularly for STEM. This proposed framework consists of digital game development as input, experience as a process, and constructs as output. This simple and precise framework will generate a universal product for various types of learners. It can thus be used as a guideline for game designers, developers, and experts to develop STEM digital games and achieve better learning outcomes.

Using games to teach science, technology, engineering, and mathematics (STEM) can enhance the quality of education. The idea of using digital games to increase individual interest towards STEM has been implemented as gaming technology has evolved in the 21st century. A correlation exists between using digital games and the learning outcomes which suggests that incorporating digital games may develop interest; however, the theoretical discussion on how interest may be developed with digital games remains inconclusive, thus, resulting in the need for further discussion. Hence, we aim to contribute with a discussion on how STEM digital games can develop individual interest in STEM. Previous studies on digital games in the STEM education context support the arguments presented in this study, therefore, there is a high probability that STEM digital games develop interest. Nevertheless, this can only be achieved with a good STEM game design and defining what is a good STEM game design is subjective. Several elements can be used as indicators to describe the quality of a design. These include the pedagogical learning content and the inclusion of fun elements within a design. Therefore, we propose the integration of theories with pedagogy, learning strategies, STEM learning content, game elements, and game principles design to ensure the presence of a three-layer process to develop interest. The creativity of game designers and developers is key to creating appealing STEM digital games providing young players with an inspiring experience.

This paper presents a 2D multiphase non-isothermal mass transfer model for a single-cell direct methanol fuel cell (DMFC). The model includes the reaction of methanol and oxygen at the anode and cathode, respectively. In addition, it also considers the diffusion of every component involved in DMFC—i.e., methanol, water and oxygen at the diffusion layer and the methanol crossover phenomena. It also includes the relation between the temperature and concentration towards the power output. Later, the model was optimised and the result shows this model can generate up to 48 mWcm−2 of power density reflected to 190 mAcm−2 and 0.26 V of current density and voltage, respectively. It shows this study generate a good model compare to previous study, at a methanol concentration of 4 M and operating temperature of 60 °C.

The direct methanol fuel cell (DMFC) is currently one of the most promising alternative power sources because of its high energy, simple design and operation. However, the DMFC still faces several problems, such as sluggish methanol oxidation and oxygen reduction, as well as a high methanol crossover. In other areas of study, it is well-known that methanol can be photocatalytically oxidized by wide band gap semiconductors under solar illumination. Methanol has been used in photocatalytic water splitting to enhance the performance of photo-electrochemical cells (PECs). Therefore, by combining photocatalytic and electro-catalytic mechanisms, methanol is expected to promote a new type of photo-assisted DMFC. In this work, the semiconductor TiO2 was used as a photo-catalyst in a PEC using a methanol solution. A TiO2 P25 suspension was cast onto carbon paper and then dried at 80 °C for 60 min. The photo-electrochemical measurements were carried out in a 3-arm electrochemical cell, using Pt wire as the counter electrode and Ag/AgCl as the reference electrode. Linear scan voltammetry (LSV) was carried out using a 20 V/400 mA potentiostat. The current densities of the electrode were monitored with and without simulated solar illumination. From the investigation, the current density of the TiO2 electrode under solar illumination was higher than it was without solar illumination. However, the value is low due to the low activity of TiO2 under visible light illumination. Further studies were carried out by combining TiO2 with a carbon material and a noble metal alloy to maximize the current density. This modified photo-catalyst can be utilized in a new photo-assisted DMFC to produce higher electricity.

The diffusion layer is an important structure in the membrane electrode assembly (MEA) of direct methanol fuel cells (DMFCs) that provide a support layer for catalysts, electronic channels, and gas–liquid mass transport channels. In this study, three types of carbon-based materials were used to fabricate anode diffusion layers – carbon black Vulcan® (CBV), M-15 grade graphene nanosheets (GM-15) and C-500 grade graphene nanosheets (GC-500). The microporous layers of cathodes were constructed with CBV. A carbon-based microporous layer with a 2 mg cm−2 loading was coated onto a PTFE-pretreated carbon cloth, while a Nafion-117 membrane was applied as the electrolyte to the DMFCs. Pt–Ru black and Pt black were used as anode and cathode electrode catalysts, each with loadings of 8 mg cm−2 and 4 mg cm−2, respectively. All tests were conducted using MEAs with active areas of 4 cm2 and air was supplied to single cells by passive modes. Surface morphology was studied using scanning electron microscopy (SEM), which produced pictures of complex network formations within the structures. CBV consists of nanosized carbon particles, while both GM-15 and GC-500 are made of stacks of graphene sheets with flaky structures that increase catalyst utilization. Performance tests of the DMFCs were conducted using a potentiostat that generated polarization curves. The highest peak power density of 13.7 mW cm−2 was obtained by the GC-500 anode diffusion layer using 3 M methanol as fuel. The energy efficiency of the passive DMFCs was approximately 10% with a specific energy of approximately 610 Wh kg−1, which is higher than that of conventional lithium-ion batteries, portraying the bright future of alternative energy sources for use in power applications for portable devices. The high power densities obtained by both graphene-based materials, GM-15 and GC-500, demonstrate that graphene is a material other than state of the art carbon black that has the potential to be used as a DMFC anode support material.

A mathematical model is developed for a liquid-feed DEAFC incorporating an alkaline anion-exchange membrane. The one-dimensional mass transport of chemical species is modelled using isothermal, single-phase and steady-state assumptions. The anode and cathode electrochemical reactions use the Tafel kinetics approach, with two limiting cases, for the reaction order. The model fully accounts for the mixed potential effects of ethanol oxidation at the cathode due to ethanol crossover via an alkaline anion-exchange membrane. In contrast to a polymer electrolyte membrane model, the current model considers the flux of ethanol at the membrane as the difference between diffusive and electroosmotic effects. The model is used to investigate the effects of the ethanol and alkali inlet feed concentrations at the anode. The model predicts that the cell performance is almost identical for different ethanol concentrations at a low current density. Moreover, the model results show that feeding the DEAFC with 5 M NaOH and 3 M ethanol at specific operating conditions yields a better performance at a higher current density. Furthermore, the model indicates that crossover effects on the DEAFC performance are significant. The cell performance decrease from its theoretical value when a parasitic current is enabled in the model.

Small fuel cells appear to be appealing solutions to the problem of providing portable energy sources. One promising system is the Direct Ethanol Fuel Cell (DEFC) stacks, which are modular and simple to construct and have certain attributes, such as being a compact and lightweight cell, that make it favorable for portable applications. Nevertheless, there are still many challenges for DEFC commercialization, such as water transport management, EtOH crossover and the sluggish Ethanol Oxidation Reaction (EOR) kinetics on the anode. The phenomena involved with DEFCs are complicated and include transport processes, thermochemical reactions and fluid mechanics that are hard to quantify experimentally. On the other hand, mathematical modeling is a powerful and economical tool that enables us to better understand the physical phenomena that occur during operation. In this study, a conceptual design was developed to obtain a power performance curve. The voltage and current characteristics with the proposed MEA geometry will be used as starting point for more detailed modeling and simulation studies that aim to provide a basic understanding of the internal process of the DEFC. This study is to be used as initial estimations for engineers to design and optimize the DEFC for use in portable applications.

The commercialization of Direct Ethanol Fuel Cells (DEFCs) is still hindered because of economic and technical reasons. Fundamental scientific research is required to more completely understanding the complex electrochemical behavior and engineering technology of DEFCs. To use the DEFC system in real-world applications, fast, reliable, and cost-effective methods are needed to explore this complex phenomenon and to predict the performance of different system designs. Thus, modeling and simulation play an important role in examining the DEFC system as well as in designing an optimized DEFC system. The current DEFC literature shows that modeling studies on DEFCs are still in their early stages and are not able to describe the DEFC system as a whole. Potential DEFC applications and their current status are also presented.

Membrane-less micro fuel cells (MMFCs) are high potential alternative power sources compared to conventional batteries. They use the advantage of laminar flow without the presence of a membrane to separate the anode and the cathode. This article is a wide-ranging review of recent studies on mass transfer, performance, modelling advances and future opportunity in MMFCs research. The discussion focuses on the critical factors that limit the performance of MMFCs. Because MMFCs are diffusion-limited, most of this review focuses on design considerations to enhance the power density output. Moreover, the current status of computational modelling for MMFC systems to upgrade the cell performance will be presented. The review also identifies the challenges and opportunities available for increasing cell performance and making the MMFC a practical application device in the future.

The aim of this research was to study the effect of the membrane electrode assembly fabrication factors on the performance of a passive micro direct methanol fuel cell by studying the hot pressing parameters. The MEA was prepared with a Nafion 117 membrane and porous electrodes having an active area of 1 cm 2 with Pt and Pt/Ru catalysts of 8 mg cm −2 loading at the cathode side and anode side, respectively. The Design of Experiment work was performed with the Response Surface Method using the Central Composite Design. The One-factor-at-a-time method was used to select the significant level of factors for the DOE method, which are temperature in the range of 100–135 °C and pressure in the range of 6.0–16.0 kgf cm −2 . The results show that the proposed mathematical model in the Response Surface Method can be used adequately for prediction and optimization within the factor levels investigated. The combined optimum hot pressing parameters that gave the highest performance of 7.23 mW cm −2 predicted in this study are temperature 130 °C and pressure 6 kgf cm −2 .

Methanol crossover through proton conducting membranes represents one of the main drawbacks in DMFCs. This study presented a novel organic-inorganic hybrid membrane with several different compositions by casting mixtures of zirconium phosphate (ZP), polybenzimidazole (PBI) and Nafion dispersion in dimethylacetamide. The presence of PBI and ZP in the membranes was demonstrated with energy dispersive X-ray (EDX) analysis. From the scanning electron microscopy (SEM) analysis, it was observed that the hybrid Nafion-PBI-ZP membrane had the finest structure. This is because the synthesized films were homogeneous and therefore formed a dense membrane. The water content was higher in the hybrid membrane: 39.91% compared with 35.52% in Nafion117. The water content is important for the ion transportation in the membrane; therefore, a higher water uptake rate will contribute to a better fuel cell performance. It was determined that the proton conductivity of the hybrid membrane was 0.020 S cm −1 , which was comparable with Nafion117, which had a proton-conductivity of 0.022 S cm −1 . The methanol permeability of the hybrid membrane was 2.34 × 10 −7 cm 2 s −1 , while the value for Nafion117 was 8.91 × 10 −7 cm 2 s −1 . This showed that the methanol permeability of the hybrid membrane was almost 4 times lower than that of Nafion117. The selectivity factor for the Nafion-PBI 1%–ZP 1% membrane was 8.64 × 10 4 Scm −3 , while that of Nafion117 was 2.48 × 10 4 S scm −3 . From a thermogravimetry analysis (TGA), the addition of PBI and zirconium phosphate was shown to improve the thermal durability in the temperature range from room temperature to 450 °C over that of Nafion117. This study proofed that the Nafion-PBI 1%–ZP 1% performed better than commercial Nafion117 and other type of membranes. The membrane was tested on as single cell of DMFC. It gave the highest power density as compared to other type of membrane and proofed that it has potential to be used in DMFCs.

The relatively inexpensive SiO2 layer was studied as the silicon etch mask in a KOH etching process for the fabrication of a flow field pattern that consists of channels as well as through-holes on the substrate of a fuel cell. The SiO2 layer was grown in a wet thermal oxidation process to obtain a thickness of up to 6.5 μm and the growth was predicted using the Deal–Grove model. The flow fields on the cathode and anode sides were done using a wet etch process with KOH as etchant. Etching time was utilized to control the depth of the required pattern and the pattern shape was found to have an influence over the etch rate. With constant monitoring of the conditions and parameters used throughout the micro-fabrication process, the thick SiO2 layer was found to be a reliable masking material for a long KOH etching.

The direct-methanol fuel cell (DMFC), a type of polymer-electrolyte membrane fuel cell, has lately received much attention because of its potential applicability as a good alternative power source for the future. In order to achieve commercially viable performance goals for the DMFC, a membrane with several important selective behaviors will need to be developed. Over roughly the past four decades, researchers have used the commercial Nafion membrane by DuPont as a proton-conductive membrane in DMFCs due to its chemical stability and high proton conductivity, as well as high mechanical strength. However, Nafion membranes also have several weaknesses such as high methanol permeability and an operational temperature limited to ∼100 °C or lower, and Nafion is also a very expensive material. Besides Nafion, there have been several engineering thermoplastic polymers such as poly(etheretherketone) (PEEK), polysulfone (PSF) and polybenzimidazole (PBI) used as alternative membranes due to their lower cost and very high mechanical and thermal stability in high temperature operation. To date, there has been continuous extensive research on developing a membrane which can fulfill all of the essential characteristics to yield the desired performance in DMFCs. In the course of this research, hybrid membranes have been developed by modifying the original membranes to produce new membranes with variously enhanced properties. This review discusses recent advances in hybrid membranes of two main types: Nafion-based and non-Nafion-based membranes. Recent achievements and prospect of applications also been included in this paper.

An unsteady-state model was developed for a liquid-feed Direct Methanol Fuel Cell (DMFC) delivery considering two-phase system. The model considered the mass and heat transport in the feed delivery system attached to the anode and cathode of the fuel cell. The results were then compared with the experimental data from in-house fabricated DMFC and steady-state model. It was observed that the unsteady-state model gave more similar results with experimental data then the steady-state model. The effects of feed methanol concentration in the reservoir and current density on mass transport to the catalyst layer were revealed.

Interests in the feasibility of micro-direct methanol fuel cells (DMFC) for commercialization, especially in the portable applications area, have encouraged the R&D sections in companies and institutions to create a better, simpler and more economical prototype. Despite the increase in knowledge on how to handle this type of cells, many challenges still remain to be conquered. There is also the question of individuality for each prototype created, which is similar to what is faced in MEMS with its lack of a single driving market, and until one dominant application can be established, fuel cell designs will continue to evolve and bringing with each of them a host of pros and cons. This paper will draw out the current challenges and development of micro-DMFC. Besides that, this paper will also show some marketing prediction in term of economics view.

Abstrac t—An extensive research has been carried out to improve the performance of direct methanol fuel cells (DMFCs) using low methanol concentration below 5 M either in active or passive conditions due to methanol crossover (MCO) problem which the methanol crosses over the membrane and reacts directly with oxygen at cathode. However, a low methanol concentration leads to a low energy density of the fuel cell system and a short runtime which cannot meet the requirement of commercialization. Therefore, it is important to use a high concentration of methanol in DMFC to achieve a high energy density. This study was done to improve the performance of passive vapor feed DMFC by using high methanol concentrations from 12 M (molarity) to neat methanol. From the results obtained, it was showed that the performance of passive vapor feed DMFC that used high methanol concentration improved. It was a linear dependence of current density on methanol concentration which is the current density increased when the methanol concentration increased up to neat. The linear dependence of current density on the concentration suggested that the cell operation was under the rate controlling by the methanol transport. Therefore, it can conclude that high methanol concentration can leads to high energy density achieved by the DMFCs.

In a passive vapor-feed direct methanol fuel cell (DMFC), methanol vapor is typically obtained using a pervaporation plate in a process by which liquid methanol contained in the fuel reservoir undergoes a phase change to vapor in the anodic vapor chamber. This work investigates the effect of pervaporation plate thickness on the rate of methanol evaporation using a three-dimensional simulation model developed by varying the plate thickness. A. The rate of methanol evaporation was measured using Darcy's law. The rate of methanol evaporation was found to be inversely proportional to the plate thickness, where the decrease in thickness inevitably lowers the resistance along the plate and consequently increases the methanol transport through the plate. This shows that the plate thickness has a significant influence on the rate of methanol evaporation and thereby plays an important role in improving the performance of the passive vapor-feed direct methanol fuel cell.

The Direct Methanol Fuel Cell (DMFC) is a promising portable power source for mobile electronic devices because of its advantages including easy fuel storage, high energy density, low temperature operation and compact structure. In DMFC, methanol is used as a fuel source where it can be fed in liquid or vapor phase. However, the vapor feed DMFC has an advantage over the liquid feed system as it has the potential to have a higher operating temperature to increase the reaction rates and power outputs, to enhance the mass transfers, to reduce methanol crossover, reliable for high methanol concentration and it can increase the fuel cell performance. Methanol vapor can be delivered to the anode by using a pervaporation membrane, heating the liquid methanol or another method that compatible. Therefore, this paper is a review on vapor feed DMFC as a better energy source than liquid feed DMFC, the pervaporation membrane used to vaporize methanol feed from the reservoir and its applications in vapor feed DMFC.

Direct methanol fuel cell is the best candidate in generating high energy density and compatible as power source for small mobile device. DMFC operate in two basic manners which are active and passive where methanol can be fed in liquid or vapoor phase. Passive DMFC is simpler than active DMFC since it operates without using any external devices to deliver methanol and air to the fuel cell. Due to methanol crossover problem faced by liquid feed DMFC operated at high methanol concentration, vapor feed DMFC is an alternative way to solve this problem. Vapor feed DMFC proposed by some groups since it can increase the fuel cell performance and reliable for high methanol concentration. Methanol vapor delivered to the anode by heating the liquid methanol or using a pervaporation membrane. However, there are challenges to overcome such as methanol crossover and water management. Mass transfer resistance should be increased to reduce the methanol crossover and Water management also needed in order to block the water removal from the cathode and thus help to push more water backward from the cathode to the anode in vapor feed DMFC operation to achieve high performance.