Research progress of biochar in the world based on bibliometrics analysis

Abstract: In order to understand in depth the status and future development trend of biochar research in the world, and to reflect scientific capabilities and influences of relevant countries, institutions and individuals objectively, a bibliometric analysis was applied to assess the literature regarding biochar research from the Web of Science database during the period of 2003 to 2020. Since 2010, the number of papers on biochar research in the world is increasing rapidly, and in 2019 alone, the number of papers has reached 1 741. The results of polynomial trend line simulation show that in 2020, the number of papers in the world will exceed 2 000. China, USA and Australia rank in the top three in the number of papers on biochar research, among which 3 608 biochar papers was published by China, accounting for 46.94% of the total. However, the average citations per paper in China is only about half of that of the USA, Australia and UK. China has 10 institutions in the global top 17 institutions, among which the Chinese Academy of Sciences are on global top of the list in number of papers, total citations and H-index. China and the USA were most active in publications collaboration. Among individuals, Ok Yong Sik of the Korea University is in the lead in number of papers, total citations and in H-index in the world. China has 8 scholars in the top 20 in the number of papers, showing a strong overall strength. Cao Xinde, from Shanghai Jiaotong University, ranked first in terms of the number of papers and average citations per paper. Among the top 10 most cited papers, only one was by Chinese authors, ranking 10th. Although published papers from China increased dramatically in recent years, the research ability, the quality and innovation of biochar research in China need to be further improved. "Science of the Total Environment" was the journal which published most of the biochar papers, while "Bioresource Technology" is the journal with the highest citations and H-index. The research topics were diversified, which were mainly divided into "Environmental Sciences", "Soil Sciences" and "Energy Fuels". Based on the results of high frequency keywords by VOSviewer visual analysis, the biochar researches was mostly classified into four clusters: the application of biochar in the soil improvement and agricultural production, wastewater treatment, remediation of polluted soil, and the preparation method and process of biochar, and the top 10 keywords in biochar researches was biochar, adsorption, carbon, pyrolysis, soil, sorption, removal, black carbon, activated carbon and water. The comparison of high-frequency keywords in different countries shows that China pays more attention to the biochar research in the treatment of environmental pollution. Additionally, CiteSpace software was further applied to analyze the focus and frontier in biochar research, and magnetic biochar, zero valent iron, nanoparticles, microbial community, organic carbon, performance and balance was the bursts keywords in the papers published from 2018 to 2020, reflecting that the preparation of new functional biochar composite materials and the application of biochar in new fields may become the research focus at present and in the future, which also means that biochar research has expanded to a broader field. These results can provide insight into the research progress regarding biochar.