Authors retract highly cited 2014 Science paper

The authors of a 2014 paper in Science have retracted it, after becoming aware that impurities in the chemicals they used for their experiments may have generated the apparent findings.

The paper, “Ammonia synthesis by N₂ and steam electrolysis in molten hydroxide suspensions of nanoscale Fe₂O₃,” has been cited 323 times, according to Clarivate Analytics’ Web of Science, earning it a “hot paper” designation. According to a summary of the work, “the protocol points to a way to produce ammonia from purely renewable resources.”

Here’s the retraction notice:

We have obtained new evidence, 6 years after the publication of our Report “Ammonia synthesis by N2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe2O3” (1), that there is a trace NOx– impurity in the nanoscale Fe2O3 that was unknown at the time. We no longer have the original nanoscale Fe2O3, and manufacturer’s content levels of impurities in chemicals may vary over time. However, recently purchased nanoscale Fe2O3 per gram contains 0.0005g N as NOx–, and, an 15N2 isotopic tracer analysis conducted by Wenzhen Li, Yifu Chen, and Hengzhou Liu at Iowa State University, Shuang Gu at Wichita State University, and author S.L., suggests that this trace impurity, rather than N2, is the major nitrogen reactant in the observed ammonia synthesis. We are retracting the original Report, and we encourage exploration of an N2 to NOx–intermediate to ammonia pathway, rather than direct elemental nitrogen pathway, to ammonia synthesis. All observed stimulation of ammonia generation with these (likely NOx–containing) nanoscale Fe2O3 materials, as well as all thermodynamic calculation results, remain accurate as documented in the original Report.

Stuart Licht, of The George Washington University and the corresponding author of the paper, did not respond to requests for comment from Retraction Watch.

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