Research trends in proton exchange membrane fuel cells during 2008-2018: A bibliometric analysis

Analyzing consumer behaviour towards food and nutrition labeling: A comprehensive review

Studying consumer behaviour towards food and nutrition labelling (F&NL) is increasingly becoming important across the world. Bibliometric analysis is a way to identify influential research, track trends, and understand methodologies in any field. In this paper, we used bibliometric analysis and a review of theories too to critically evaluate theories and concepts used in studying consumer behaviour towards F&NL. Using the Scopus database, we obtained 1017 articles, which were further filtered to perform various analyses like Co-occurrence and co-authorship network analysis. We found limited East and Southeast Asia-based research. Personal beliefs, attitudes, and past experiences were identified as influencers of consumer behaviour regarding food labelling. Trending topics were food waste, purchase intention, and sustainability labels.

A scientometric review of hotspots and emerging trends in sustainable business model

A sustainable business model (SBM) has become an inevitable trend for the traditional business model to follow the development of the times. Based on scientometrics, we explored and visually analyzed SBM's hotspots and emerging trends using the references co-citation networks, landmark references, burst references, keywords co-occurring networks, timeline map, and burst keywords indicators. Our findings consist of four aspects: hotspots and emerging trends, hotspots evolution history, landmark references, and burst references evolution history. First, the core hotspots are "sustainable innovation" and "open innovation". Second, the main hotspots have evolved from "sustainable innovation," "strategy," "performance," and "supply chain" from 1998 to 2012 into "resource-based view," "product-service system," "China," "life cycle assessment," and "conceptual framework" in 2013-2017. And "circular economy," "renewable energy," "value creation," "decarbonization" have appeared since 2019, which are emerging trends of SBM. Third, we have found ten landmark references in total. Articles written by Bocken & Short, Boons & Ludeke-Freund, and Zott & Amit are the three most landmark references that significantly impact the whole field. Last, the top 10 cited references have burst since 2011 and lasted until 2022. The article written by Teece became a long-term cited hotspot from 2011 to 2018. Moreover, the article written by Geissdoerfer & Vladimirova, which burst in 2020-2022, was the most cutting-edge. This research aims to enrich the existing research theories related to SBM and help governments and enterprises capture hotspots and emerging trends of SBM so that they can better understand and study SBM.

N,S-co-doped FeCo Nanoparticles Supported on Porous Carbon Nanofibers as Efficient and Durable Oxygen Reduction Catalysts

Finding high-performance, low-cost, efficient catalysts for oxygen reduction reactions (ORR) is essential for sustainable energy conversion systems. Herein, highly efficient and durable iron (Fe) and cobalt (Co)-supported nitrogen (N) and sulfur (S) co-doped three-dimensional carbon nanofibers (FeCo-N, S@CNFs) were synthesized via electrospinning followed by carbonization. The as-prepared FeCo-N,S@CNFs served as efficient ORR catalysts in alkaline 0.1 m KOH solutions that were N₂ and O₂ -saturated. The experimental results revealed that FeCo-N,S@CNFs were highly active ORR catalysts with defect-rich active pyridinic N and pyrrolic N and metal bonds to N and S atom sites, which enhanced the ORR activity. FeCo-N,S@CNFs exhibited a high onset potential (E_onset =0.89 V) and half-wave potential (E_1/2 =0.85 V), similar to the electrocatalytic activity of commercial Pt/C. Additionally, the durability of the as-prepared FeCo-N,S@CNFs catalysts was maintained for 14 h with long-term stability and high tolerance to methanol stability, accounting for their excellent catalytic ability. Furthermore, Co-N@CNFs, Fe-N@CNFs, and varying Fe and Co ratios were compared with those of FeCo-N,S@CNFs. Synergistic interactions between metals and heteroatoms were believed to play a significant role in enhancing the ORR activity. Owing to their excellent catalytic reduction ability, the as-prepared FeCo-N,S@CNFs can be widely used in battery-based systems and replace commercial Pt/C in fuel cell applications.

Board gender diversity and corporate social responsibility: A bibliometric analysis

The objective of this study to analyze developments in relating to board gender diversity (BGD) and corporate social responsibility (CSR) research and provide future researchers with new avenues for research in the field. A bibliometric analysis was conducted by focusing on the most productive articles, authors, journals, institutions, sponsors, and countries and as co-occurrence analyses based on 1961 peer-reviewed articles published between January 1966 and April 2021 in the Scopus database. Results revealed that the number of publications relevant to BGD and CSR has been gradually increasing, and a significant increase has been observed since 2010. Keywords such as "gender," "gender equality," "sustainable development," and "corporate social responsibility" reveal the key themes in BGD and CSR research. Cluster analysis revealed three clusters: Cluster 1 focused primarily on the board composition and board structure, Cluster 2 focused on board composition and its connection to CSR or philanthropy, and Cluster 3 (comprising more recent articles) mainly stressed the impact of gender diversity on CSR or sustainability initiatives. Results also provided different implications with future research directions. It reveals the collaboration between authors in conducting research in the domain of BGD and CSR is still lacking, suggesting further research in collaboration different authors in CSR and BGD. Journal of business ethics, Corporate governance: an international review, and Academy of management journal were the top-ranking journals in term of source co-citation, and thus journals ought to be further expanded more research in CSR and BGD to enhance their source co-citations. The most productive sponsors and institutions were in developed countries, while country co-authorship analysis revealed more research need to cooperatively be undertaken in developing countries.

A Bibliometric Study on Trends in Proton Exchange Membrane Fuel Cell Research during 1990-2022

Proton exchange membrane fuel cell (PEMFC) with high density and safe reliability has been extensively studied in the world. With the circumstance of extensive PEMFC research, in this study we carried out a bibliometric analysis to understand the technological development. The information of 17,769 related publications from 1990 to 2022 was retrieved from the Web of Science Core Collection for bibliometric analysis based on the VOSviewer tool. The results show that the International Journal of Hydrogen Energy dominates among all of the source journals. The closest collaboration is between China and the USA, and publications from both of those account for 53.9% of the total. In terms of institutions, the Chinese Academy of Sciences has prolific publications, in which representative groups, such as Shao Zhigang's, have achieved many outputs in this field. The theme of PEMFC research can be divided into three aspects: "materials", "design" and "mechanisms". This study demonstrated overall mapping knowledge domain and systematic analysis, and contributed to making a guide for researchers on the progress and trends of PEMFC.

Review on Magnetism in Catalysis: From Theory to PEMFC Applications of 3d Metal Pt-Based Alloys

The relationship between magnetism and catalysis has been an important topic since the mid-20th century. At present time, the scientific community is well aware that a full comprehension of this relationship is required to face modern challenges, such as the need for clean energy technology. The successful use of (para-)magnetic materials has already been corroborated in catalytic processes, such as hydrogenation, Fenton reaction and ammonia synthesis. These catalysts typically contain transition metals from the first to the third row and are affected by the presence of an external magnetic field. Nowadays, it appears that the most promising approach to reach the goal of a more sustainable future is via ferromagnetic conducting catalysts containing open-shell metals (i.e., Fe, Co and Ni) with extra stabilization coming from the presence of an external magnetic field. However, understanding how intrinsic and extrinsic magnetic features are related to catalysis is still a complex task, especially when catalytic performances are improved by these magnetic phenomena. In the present review, we introduce the relationship between magnetism and catalysis and outline its importance in the production of clean energy, by describing the representative case of 3d metal Pt-based alloys, which are extensively investigated and exploited in PEM fuel cells.

Experimental Analysis of a Fuzzy Scheme against a Robust Controller for a Proton Exchange Membrane Fuel Cell System

Proton exchange membrane fuel cells (PEMFC) are capable of transforming chemical energy into electrical energy with zero emissions. Therefore, these devices had been a point of attention for the scientific community as to provide another solution to renewable sources of energy. Since the PEMFC is commonly driven with a power converter, a controller has to be implemented to supply a convenient voltage. This is an important task as it allows the system to be driven at an operative point, which can be related to the maximum power or an user desired spot. Along this research article, a robust controller was compared against a fuzzy logic strategy (with symmetric membership functions) where both were implemented to a commercial PEMFC through a dSPACE 1102 control board. Both proposals were analysed in an experimental test bench. Outcomes showed the advantages and disadvantages of each scheme in chattering reduction, accuracy, and convergence speed.

Research and Development Investment and Collaboration Framework for the Hydrogen Economy in South Korea

South Korea developed its hydrogen strategies to achieve carbon neutrality and dominate the hydrogen economy amidst, and with the impetus, of the coronavirus disease 2019 (COVID-19) pandemic. The government strives toward the goal via continuous investment in green hydrogen technologies, as well as strategic collaborations. To facilitate the transition into the hydrogen economy, this study presents a research and development (R&D) investment and collaboration framework as a national strategy. The framework offers abundant information to elucidate the technology, R&D spectrum, and regional dimensions of the strategy. Furthermore, the proposed framework was applied to the Korean hydrogen economy comprising 955 nationally funded projects worth USD 565.7 million. The statuses and trends of the government’s investment in nationally funded research projects are illustrated with regard to the value chains of the hydrogen economies of 16 regions, as well as nine technology clusters relating to the hydrogen economy, thereby determining the research organizations that played crucial roles in each cluster of the 16 regions between 2015 and 2020. The results indicate that the research organizations in Daejeon acquired the highest government R&D funding in many hydrogen-economy-related research fields, and that an R&D spectrum-based research/strategic collaboration is required to accomplish specialized complexes in the regions.

Evolutionary Overview of Consumer Health Informatics: Bibliometric Study on the Web of Science from 1999 to 2019

BACKGROUND

Consumer health informatics (CHI) originated in the 1990s. With the rapid development of computer and information technology for health decision making, an increasing number of consumers have obtained health-related information through the internet, and CHI has also attracted the attention of an increasing number of scholars.

OBJECTIVE

The aim of this study was to analyze the research themes and evolution characteristics of different study periods and to discuss the dynamic evolution path and research theme rules in a time-series framework from the perspective of a strategy map and a data flow in CHI.

METHODS

The Web of Science core collection database of the Institute for Scientific Information was used as the data source to retrieve relevant articles in the field of CHI. SciMAT was used to preprocess the literature data and construct the overlapping map, evolution map, strategic diagram, and cluster network characterized by keywords. Besides, a bibliometric analysis of the general characteristics, the evolutionary characteristics of the theme, and the evolutionary path of the theme was conducted.

RESULTS

A total of 986 articles were obtained after the retrieval, and 931 articles met the document-type requirement. In the past 21 years, the number of articles increased every year, with a remarkable growth after 2015. The research content in 4 different study periods formed the following 38 themes: patient education, medicine, needs, and bibliographic database in the 1999-2003 study period; world wide web, patient education, eHealth, patients, medication, terminology, behavior, technology, and disease in the 2004-2008 study period; websites, information seeking, physicians, attitudes, technology, risk, food labeling, patient, strategies, patient education, and eHealth in the 2009-2014 study period; and electronic medical records, health information seeking, attitudes, health communication, breast cancer, health literacy, technology, natural language processing, user-centered design, pharmacy, academic libraries, costs, internet utilization, and online health information in the 2015-2019 study period. Besides, these themes formed 10 evolution paths in 3 research directions: patient education and intervention, consumer demand attitude and behavior, and internet information technology application.

CONCLUSIONS

Averaging 93 publications every year since 2015, CHI research is in a rapid growth period. The research themes mainly focus on patient education, health information needs, health information search behavior, health behavior intervention, health literacy, health information technology, eHealth, and other aspects. Patient education and intervention research, consumer demand, attitude, and behavior research comprise the main theme evolution path, whose evolution process has been relatively stable. This evolution path will continue to become the research hotspot in this field. Research on the internet and information technology application is a secondary theme evolution path with development potential.

Ion-Exchanged UPG-1 as Potential Electrolyte for Fuel Cells

Proton-exchange membrane fuel cells are an attractive green technology for energy production. However, one of their major drawbacks is instability of the electrolytes under working conditions (i.e., temperature and humidity). Some metal-organic frameworks (MOFs) have recently emerged as promising alternative electrolyte materials because of their higher stability (compared with the organic polymers currently used as electrolytes), proton conductivity, and outstanding porosity and versatility. Here, we present ionic exchange in a microporous zirconium phosphonate, UPG-1, as an efficient strategy to enhance its conductivity and cyclability. Thus, labile protons of the hybrid structure were successfully replaced by different alkali cations (Li⁺, Na⁺, and K⁺), leading to 2 orders of magnitude higher proton conductivity than the pristine UPG-1 (up to 2.3 × 10^-2 S·cm^-1, which is comparable with those of the commercial electrolytes). Further, the proton conductivity was strongly influenced by the MOF hydrophilicity and the polarization strength of the cation, as suggested by molecular simulation. Finally, a mixed-matrix membrane containing the best-performing material (the potassium-exchanged one) was successfully prepared, showing moderate proton conductivity (up to 8.51 × 10^-3 S·cm^-1).

Performance assessment and economic perspectives of integrated PEM fuel cell and PEM electrolyzer for electric power generation

The study presents a complete one-dimensional model to evaluate the parameters that describe the operation of a Proton Exchange Membrane (PEM) electrolyzer and PEM fuel cell. The mathematical modeling is implemented in Matlab/Simulink® software to evaluate the influence of parameters such as temperature, pressure, and overpotentials on the overall performance. The models are further merged into an integrated electrolyzer-fuel cell system for electrical power generation. The operational description of the integrated system focuses on estimating the overall efficiency as a novel indicator. Additionally, the study presents an economic assessment to evaluate the cost-effectiveness based on different economic metrics such as capital cost, electricity cost, and payback period. The parametric analysis showed that as the temperature rises from 30 to 70 °C in both devices, the efficiency is improved between 5-20%. In contrast, pressure differences feature less relevance on the overall performance. Ohmic and activation overpotentials are highlighted for the highest impact on the generated and required voltage. Overall, the current density exhibited an inverse relation with the efficiency of both devices. The economic evaluation revealed that the integrated system can operate at variable load conditions while maintaining an electricity cost between 0.3-0.45 $/kWh. Also, the capital cost can be reduced up to 25% while operating at a low current density and maximum temperature. The payback period varies between 6-10 years for an operational temperature of 70 °C, which reinforces the viability of the system. Overall, hydrogen-powered systems stand as a promising technology to overcome energy transition as they provide robust operation from both energetic and economic viewpoints.

Effects of the Chemical Treatment on the Physical-Chemical and Electrochemical Properties of the Commercial Nafion™ NR212 Membrane

Polymer Electrolyte Fuel Cells (PEFCs) are one of the most promising power generation systems. The main component of a PEFC is the proton exchange membrane (PEM), object of intense research to improve the efficiency of the cell. The most commonly and commercially successful used PEMs are Nafion™ perfluorosulfonic acid (PFSA) membranes, taken as a reference for the development of innovative and alternative membranes. Usually, these membranes undergo different pre-treatments to enhance their characteristics. With the aim of understanding the utility and the effects of such pre-treatments, in this study, a commercial Nafion™ NR212 membrane was subjected to two different chemical pre-treatments, before usage. HNO3 or H2O2 were selected as chemical agents because the most widely used ones in the procedure protocols in order to prepare the membrane in a well-defined reference state. The pre-treated membranes properties were compared to an untreated membrane, used as-received. The investigation has showed that the pre-treatments enhance the hydrophilicity and increase the water molecules coordinated to the sulphonic groups in the membrane structure, on the other hand the swelling of the membranes also increases. As a consequence, the untreated membrane shows a better mechanical resistance, a good electrochemical performance and durability in fuel cell operations, orienting toward the use of the NR212 membrane without any chemical pre-treatment.

Proton Conductive Zr-Phosphonate UPG-1-Aminoacid Insertion as Proton Carrier Stabilizer

Proton exchange membrane fuel cells (PEMFCs) are an attractive green technology for energy generation. The poor stability and performances under working conditions of the current electrolytes are their major drawbacks. Metal-Organic Frameworks (MOFs) have recently emerged as an alternative to overcome these issues. Here, we propose a robust Zr-phosphonate MOF (UPG-1) bearing labile protons able to act a priori as an efficient electrolyte in PEMFCs. Further, in an attempt to further enhance the stability and conductivity of UPG-1, a proton carrier (the amino acid Lysine, Lys) was successfully encapsulated within its porosity. The behaviors of both solids as an electrolyte were investigated by a complete experimental (impedance spectroscopy, water sorption) and computational approach (MonteCarlo, water sorption). Compared with the pristine UPG-1, the newly prepared Lys@UPG-1 composite showed similar proton conductivity but a higher stability, which allows a better cyclability. This improved cyclability is mainly related to the different hydrophobic-hydrophilic balance of the Lys@UPG-1 and UPG-1 and the steric protection of the reactive sites of the MOF by the Lys.

Comparative Performance of a Hybrid Renewable Energy Generation System with Dynamic Load Demand

This article presents the modeling and simulation of a hybrid generation system, which uses solar energy generation, wind energy, and the regulation of a proton exchange membrane (PEM) cell to raise the demanded load, empowering the use of these hydride systems worldwide. This generation system was simulated for different locations in Puerto Bolivar (Colombia), Bremen (Germany), Beijing (China), and Texas (USA), for two demand profiles. The data used for the simulation was calculated using the mathematical solar model proposed by Beistow and Campbell for solar radiation. In contrast, for the wind resource evaluation, the Weibull probability distribution was used to calculate the most probable wind speed for each day, according to the historical data for each of the studied locations. Considering these data, the process transfer functions were used for tuning the control parameters for the hydrogen and oxygen production system. For the evaluation of the performance of these controllers, the indices of the absolute value of the error (IAE), the integral of the square of the error (ISE), the integral of the absolute value of the error for time (ITAE), and the integral of the square of the error for time (ITSE) were used. It was found that in the second load profile studied, better performance of the ITSE performance parameter was obtained, with stabilization times lower than those of the first profile.

Fuel-Cell Electric Vehicles: Plotting a Scientific and Technological Knowledge Map

The fuel-cell electric vehicle (FCEV) has been defined as a promising way to avoid road transport greenhouse emissions, but nowadays, they are not commercially available. However, few studies have attempted to monitor the global scientific research and technological profile of FCEVs. For this reason, scientific research and technological development in the field of FCEV from 1999 to 2019 have been researched using bibliometric and patent data analysis, including network analysis. Based on reports, the current status indicates that FCEV research topics have reached maturity. In addition, the analysis reveals other important findings: (1) The USA is the most productive in science and patent jurisdiction; (2) both Chinese universities and their authors are the most productive in science; however, technological development is led by Japanese car manufacturers; (3) in scientific research, collaboration is located within the tri-polar world (North America–Europe–Asia-Pacific); nonetheless, technological development is isolated to collaborations between companies of the same automotive group; (4) science is currently directing its efforts towards hydrogen production and storage, energy management systems related to battery and hydrogen energy, Life Cycle Assessment, and greenhouse gas (GHG) emissions. The technological development focuses on technologies related to electrically propelled vehicles; (5) the International Journal of Hydrogen Energy and SAE Technical Papers are the two most important sources of knowledge diffusion. This study concludes by outlining the knowledge map and directions for further research.