Production and application of biochar: a bibliometric–bibliographic study from 2004 to 2023

Biochar is a carbon-rich material that has attracted considerable interest and has generated an important literature across various academic disciplines in the past decade. Environmental applications of biochar include climate change mitigation, waste management, soil fertility improvement, and contaminant remediation. In this study, a bibliometric analysis was performed to visualise the current research status and emerging trends in the field of biochar production and application research. A total of 33 718 documents related to the topic of biochar were collected from the Scopus database, covering the period from 2004 to December 2023. These publications were analysed using the bibliometric tools provided by the Bibliometrix package R and VOSviewer. The analysis focused on publication output, subject areas, authors, journals, institutions, and countries. The leading subject area is Environmental Science, and most articles are published in the Journal of Environmental Science and Pollution Research. China and the USA are the leading countries contributing in the number of publications, with China producing 17 096 publications and the USA 4255 publications. Based on the keyword co-occurrence analyses, in the last 5 years, searches on biochar are mainly focused on ‘biochar for adsorption’, ‘Biochar for global warming mitigation’, and ‘Biochar for heavy metals immobilisation’. Finally, the literature review highlighted several underexplored areas in biochar research, mainly using artificial intelligence to determine optimal production parameters for specific biochar applications and the scarcity of thorough assessment of the entire biochar life cycle. This review offers essential insights for stakeholders and researchers on the most extensively studied topics related to biochar production and applications, helping to identify areas that have received less attention.