Flexible point-of-use phosphate electrochemical sensors based on electrodeposited molybdenum oxide

Siqi Yu; Xiyu Sun; Zinan Yu; Jinwook Jung; Satoshi Ishii; Christopher T. Hayes; Valérie C. Pierre; Amar H. Flood; Jason D. Azoulay; Tse Nga Ng

doi:10.1039/D5MH00692A

Flexible point-of-use phosphate electrochemical sensors based on electrodeposited molybdenum oxide†

Siqi Yu,^a Xiyu Sun,^a Zinan Yu,

^b Jinwook Jung,^c Satoshi Ishii,

^dh Christopher T. Hayes,

^e Valérie C. Pierre,

^b Amar H. Flood,

^f Jason D. Azoulay

^g and Tse Nga Ng

*^ac

Author affiliations

* Corresponding authors

^a Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA 92093, USA
E-mail: tnn046@ucsd.edu

^b Department of Chemistry, The University of Utah, Salt Lake City, UT 84112, USA

^c Program in Materials Science and Engineering, University of California San Diego, La Jolla, CA 92093, USA

^d Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN 55108, USA

^e School of Ocean Science and Engineering, University of Southern Mississippi, Stennis Space Center, MS 39529, USA

^f Department of Chemistry, Indiana University, Bloomington, IN 47405, USA

^g School of Chemistry and Biochemistry and School of Materials Science and Engineering, Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA 30332, USA

^h BioTechnology Institute, University of Minnesota, St. Paul, USA

Abstract

To enable in situ phosphate monitoring for healthcare and environmental sustainability, this work demonstrates an electrochemical sensor based on electrodeposited mixed-valence molybdenum oxide (MoO_x) for selective phosphate sensing in complex aqueous media. The MoO_x film induces strong, specific detection through coordination between Mo centers and phosphate anions, generating well-defined redox signals under square wave voltammetry. The sensor exhibits a broad linear dynamic range between 10–1000 μM, a sensitive detection limit of 8 μM, and high specificity against competing anions including Cl⁻, SO₄²⁻, NO₃⁻, CO₃²⁻, and SiO₃²⁻. The sensors accurately measure phosphate levels in artificial saliva and influent wastewater field samples, with results validated to match those of standard molybdenum blue assays. The compact, flexible system achieves stable performance across varying ionic strengths, proving its robustness as a low-cost point-of-use monitoring platform for phosphate.

This article is part of the themed collection: Soft wearable sensors

Materials Horizons

Flexible point-of-use phosphate electrochemical sensors based on electrodeposited molybdenum oxide†

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Flexible point-of-use phosphate electrochemical sensors based on electrodeposited molybdenum oxide

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