Supplementary material for the article "Identification of relevant research topics based on pooled bibliometric data of the International Journal of Hydrogen Energy publications for 2022–2024 from The Lens and ScienceDirect platforms"

The article is scheduled to be published in 2025 in the online scientific journal Actual Problems of Oil and Gas (https://oilgasjournal.ru).Abstract. Background. Hydrogen is given the role of a clean energy carrier in the energy transition. Objective. To identify relevant research topics based on pooled bibliometric data of the International Journal of Hydrogen Energy publications from 2022–2024, collected from The Lens and ScienceDirect platforms. Materials and methods. 10,928 bibliometric records were exported from The Lens database and 10,857 records were exported from ScienceDirect. Keywords clustering and visual data analysis were performed using the following programs and algorithms: VOSviewer, Scimago Graphica, Inkscape, FP-growth utility. Results. The study showed the feasibility of merging bibliometric records from the open platforms ScienceDirect and The Lens, which complement each other. The “Fields of Study” data of The Lens was interpreted as system keywords similar to Scopus Index Keywords. The possibility of using “Fields of Study” data in a method similar to bibliographic coupling is shown. The practicality of using an alluvial diagram to show the co-occurrence of the four terms was demonstrated. The study also emphasizes the advisability of joint use of VOSviewer and Scimago Graphica programs for complex visualization of bibliometric analysis results. The study identified two dominant publication topics in the International Journal of Hydrogen Energy for 2022–2024, which can be described in terms of: “Catalysis, Hydrogen, Physical_chemistry, Chemical_engineering, Nanotechnology, Electrochemistry, Organic_chemistry, Materials_science” and “Electrical_engineering, Hydrogen_production, Renewable_energy, Environmental_science, Hydrogen_economy, Hydrogen, Engineering”. Conclusions. Joint use of metadata of different open abstract databases allows to compensate partial representation of their data.