Hydrogen-fuelled internal combustion engines - Bibliometric analysis on research trends, hotspots, and challenges

The advancement of hydrogen -fuelled internal combustion engines (H2ICEs) encourages a growing interest in studying the economic viability of hydrogen as a fuel for internal combustion engines (ICEs). The current study is a literature review based on the bibliometric method to analyse bibliographic data and generate visual representations and historical development of scientific studies on H2ICEs. The study analyses 2892 Scopus database documents from 1927 to 2023, including publication trends, publication types, research areas, sources, citations, collaborations, bursts, and keywords analysis, using VOSviewer (v1.6.19), CiteSpace (v6.2. R4), and Microsoft Excel. China, India, the United States, and Verhelst S., with a burst strength of 14.18, prevail in H2ICE studies. The analysis suggests major hotspot keywords for future studies, including nanoparticles, ammonia, machine learning, optimisation, injection strategy, learning algorithms, and ignition timing, with a focus on addressing major concerns, including knock, backfire, NOx emissions, and optimising the thermal and fuel efficiency of the engine.