PLOS ONE retracts hydrogen-enriched biodiesel engine study over references and AI policy

The editors of PLOS ONE have retracted a 2025 research article concerning engine performance and emissions, hydrogen-enriched biodiesel and an analytical approach identified in the paper’s title as grey relational analysis. The retraction, attributed to the PLOS ONE Editors and dated October 21, 2026, cites concerns about unretrievable references and compliance with the journal’s policies on artificial intelligence tools and technologies.

The notice lists 37 references that could not be retrieved: references 3, 4, 7, 8, 9, 10, 11, 13, 14, 17, 19, 20, 21, 22, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46 and 47. It does not provide details about the article’s experimental procedure, test conditions, numerical measurements, statistical uncertainty or comparative results, so the supplied retraction record does not support conclusions about engine output, fuel efficiency or emissions.

The retracted paper was published in PLOS ONE in December 2025 as article e0339019. Its title describes an investigation of performance and emission optimization in a CRDI engine operating in RCCI mode with hydrogen-enriched biodiesel through a grey relational analysis approach. The retraction notice does not define those technical abbreviations, describe how the fuels or engine settings were evaluated, or present the underlying findings. The paper’s title therefore indicates its stated subject but does not establish the validity of its results.

The editors said they regretted that the issues had not been identified before publication, and all of the article’s authors agreed with the retraction. The journal record consequently marks the 2025 paper as retracted. The notice gives no information about whether a corrected version will be published or whether the experimental work will be reassessed, so the present record supports only the fact of the retraction and its stated reasons—not any claim about the engine technology’s performance.

Subject of Research: A retraction of a 2025 engine-performance and emissions study over unretrievable references and journal AI-policy compliance concerns.

Article Title: Retraction: Performance and emission optimization of a CRDI engine in RCCI mode using hydrogen enriched biodiesel through grey relational analysis approach

Article References: The PLOS One Editors (2026). Retraction: Performance and emission optimization of a CRDI engine in RCCI mode using hydrogen enriched biodiesel through grey relational analysis approach. PLOS One, 21(10), e0360871. https://doi.org/10.1371/journal.pone.0360871

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360871

Keywords: PLOS ONE, research retraction, engine performance, engine emissions, hydrogen-enriched biodiesel, grey relational analysis, artificial intelligence policy, publication integrity, Retraction, Performance, emission, optimization