Green Alternatives to Zinc Dialkyldithiophosphates: Vanadium Oxide Based Additives

Andrew Johnson, Elizabeth Willneff, Sven Schroeder, Anne Neville, Callum Sweeney, Joshua J. Smith, Kathyola Thokozile, James Parish, Andrew Straiton, Ardian Morina

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We demonstrate here that a functionalized vanadyl(IV) acety-lacetonate (acac) complex is a superior and highly effective antiwear agent, affording remarkable wear protection compared to the current industry standard, zinc dialkyldithiophosphates (ZDDPs). Analysis of vanadium speciation and the depth profile of the active tribofilms by a combination of X-ray absorption near-edge structure (XANES), X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) indicated a mixed va-lence oxide composite, comprising V(III), V(IV) and V(V) species. A marked difference in composition between the bulk and the sur-face of the tribofilms was found. The vanadyl(VI) acac precursor has the potential to reduce the use of, or even replace, ZDDP, which would represent a paradigm shift in antiwear agent design. A major benefit relative to ZDDPs is the absence of S and P moieties, eliminating the potential for forming noxious and environmentally harmful by-products of these elements.
Original languageEnglish
JournalACS Applied Engineering Materials
Early online date31 Oct 2023
Publication statusPublished - 31 Oct 2023

Bibliographical note

This manuscript is dedicated to the memory of Prof. Anne Neville (1970−2022). The authors thank the Diamond Light Source for the award of beamtime at I18 and B07 under proposal numbers SP28437 and SI29334. Infineum UK Ltd. is thanked for the provision of PhD studentships for A.J.S. and C.S. and PDRA funding for J.D.P. and T.A.K. We gratefully acknowledge EPSRC support for T.A.K. through the University of Leeds Impact Acceleration Account (EP/R511717/1). A.L.J. wishes to thank the Department of Chemistry at the University of Bath. S.L.M.S. was financially supported by EPSRC through the Future Continuous Manufacturing and Advanced Crystallization (CMAC) Hub (EP/P006965/1) as well as through the Royal Academy of Engineering Bragg Centenary Chair supported by the Diamond Light Source and Infineum UK Ltd. The authors would also like to thank Stuart L. Micklethwaite (University of Leeds), Zabeeda P. Aslam (University of Leeds), Chun Wang (University of Leeds), Paul T. Edwards (University of Leeds), James M. Bucag (University of Leeds), and Stuart A. Bartlett (Diamond Light Source) for their help collecting the SEM–EDX, TEM, AFM, NEXAFS, and XANES data.


  • Antiwear Additives
  • Molecular Structures
  • Zirconium
  • Titanium
  • Vanadium
  • metal oxide


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