Microchimica Acta

, 186:640 | Cite as

Fluorometric sensing of pH values using green-emitting black phosphorus quantum dots

  • Qiaoli YueEmail author
  • Yingying Hu
  • Lixia Tao
  • Baoqian Zhang
  • Chen Liu
  • Yongping Wang
  • Chunying Chen
  • Jinsheng Zhao
  • Chen-Zhong Li
Original Paper


A fluorometric method is described for “turn-on” sensing of pH values via black phosphorus quantum dots (BPQD). Water-stable BPQD were synthesized by a liquid exfoliation method and characterized by TEM, FT-IR, XPS, and absorption and fluorescence spectra. The nanoparticles of BPQD have a uniform distribution with an average size of 5.2 nm. They exhibit bright green fluorescence, with excitation/emission maxima at 420/515 nm. The fluorescence of the BPQD is likely to arise from the quasi-molecular fluorophores of polycyclic aromatic compounds carrying P-P, P-O-P, and PxOy functions on its surface. The protonation and deprotonation of hydroxyl groups of BPQD causes a different degree of quenching of the BPQD. At pH values below 4.0, protons bind to BPQD to form non-fluorescent ground state complexes. At pH values above 4.0, the hydroxyl groups become deprotonated, and this induces the recovery of fluorescence. The sensor has a linear response in the pH range of 1.0–9.0. It was successfully applied to the determination of the pH values in human urine and serum samples.

Graphical abstract

Schematic representation of the preparation of black phosphorus quantum dots (BPQDs) from powdered BP crystals using liquid-phase exfoliation in N-methyl-2-pyrrolidone solution. The BPQDs display green fluorescence at high pH values but no fluorescence at very low pH values.


Black phosphorus quantum dots pH sensor Green fluorescence Water-stability Liquid exfoliation Protonation Deprotonation Fluorometry Human urine Human serum 



This work was financially supported by the Natural Science Foundation of China (91543206), the Natural Science Foundation (ZR2014BQ017, ZR2015BM024, and 2013SJGZ07) and the Tai-Shan Scholar Research Fund of Shandong Province and research foundation of Liaocheng University.

Compliance with ethical standards

The authors declare that they have no competing interests.

Supplementary material

604_2019_3768_MOESM1_ESM.doc (528 kb)
ESM 1 (DOC 528 kb)


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Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2019

Authors and Affiliations

  • Qiaoli Yue
    • 1
    Email author
  • Yingying Hu
    • 1
  • Lixia Tao
    • 1
  • Baoqian Zhang
    • 1
  • Chen Liu
    • 1
  • Yongping Wang
    • 1
  • Chunying Chen
    • 3
  • Jinsheng Zhao
    • 1
  • Chen-Zhong Li
    • 1
    • 2
  1. 1.Department of ChemistryLiaocheng UniversityLiaochengChina
  2. 2.Nanobioengineering/Bioelectronics Laboratory, Department of Biomedical EngineeringFlorida International UniversityMiamiUSA
  3. 3.CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China and Institute of High Energy PhysicsChinese Academy of Sciences (CAS)BeijingChina

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