Analyzing the Research Trends in Biohydrogen Production Strategy: A Longitudinal Techno‐Historical Study

ABSTRACT The constantly rising global energy demand creates a necessity for new and sustainable renewable fuels to address related issues with greenhouse gas releasing, including climate change. This aids in the progress towards decarbonization. Consequently, lately in recent years, biohydrogen has been regarded as a potential key player in worldwide renewable energy initiatives, where the production of biohydrogen is receiving increased attention in comparison to hydrogen derived from fossil fuels. The focus of this review is to give an overview of current research status and to identify the research gap in the field of biohydrogen production and evaluation of the study carried out throughout this period 1996—till March 2025. The search term is “biohydrogen production”; the related information was gathered from the WoS database and VoS viewer. The study includes literature on the ways that biohydrogen is made by biophotolysis, photofermentation, and dark fermentation. The analysis was performed based on the different documents and different languages, high productivity of authors, institutions, journals, keywords, and cited articles. Most biohydrogen productive countries are China, India, South Korea, and the USA. This study gives us the numbers that we need to understand biohydrogen for researchers to extend their research, which eventually leads to more publications in biohydrogen production.