Sains Malaysiana 47(8)(2018): 1913–1922

http://dx.doi.org/10.17576/jsm-2018-4708-33

 

XPS Study of Sulfur and Phosphorus Compounds with Different Oxidation States

(Kajian XPS untuk Sebatian Sulfur dan Fosforus yang Mempunyai Pengoksidaan yang Berbeza)

 

KIM S. SIOW^1,2*, LEANNE BRITCHER¹, SUNIL KUMAR^1,3 & HANS J GRIESSER^1,4

 

¹Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia

 

²Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

 

³Coatings Mantra Science and Technology Consulting, 11 Beresina Place, Greenwith, Adelaide,

SA 5125, Australia

 

⁴Mawson Institute, University of South Australia, Mawson Lakes, SA 5095, Australia

 

Diserahkan: 9 Februari 2018/Diterima: 14 Mac 2018

 

ABSTRACT

In this report, we demonstrate that continuous improvement in XPS instruments and the calibration standards as well as analysis with standard component-fitting procedures can be used to determine the binding energies of compounds containing phosphorus and sulfur of different oxidation states with higher confidence. Based on such improved XPS analyses, the binding energies (BEs) of S2p signals for sulfur of increasing oxidation state are determined to be 166-167.5 eV for S=O in dimethyl sulfoxide, 168.1 eV for S=O₂ in polysulfone, 168.4 eV for SO₃ in polystyrene sulfonate and 168.8 eV for SO₄ in chondroitin sulfate. The BEs of P2p signals show the following values: 132.9 eV for PO₃ in triisopropyl phosphite, 133.3 eV for PO₄ in glycerol phosphate, 133.5 eV for PO₄ in sodium tripolyphosphate and 134.0 eV for PO₄ in sodium hexametaphosphate. These results showed that there are only small increases in the binding energy when additional oxygen atoms are added to the S-O chemical group. A similar result is obtained when the fourth oxygen or poly-phosphate environment is added to the phosphorus compound. These BE values are useful to researchers involved in identifying oxidation states of phosphorus and sulfur atoms commonly observed on modified surfaces and interfaces found in applications such as biomaterials, super-capacitors and catalysis.

 

Keywords: Binding energies; oxidation state; phosphorus; sulfur; XPS

 

ABSTRAK

Kajian ini menunjukkan bahawa penambahbaikan yang berterusan dalam spektroskopi foto-elektron x-ray (XPS), piawaian penentukuran dan prosedur pencocokan lengkung puncak, boleh menentukan tenaga pengikat untuk sebatian fosforus dan sulfur yang terdiri daripada pengoksidaan yang berbeza dengan lebih jitu. Berdasarkan analisis XPS ini, tenaga pengikat (BE) untuk puncak S2p daripada sebatian sulfur yang mempunyai pengoksidaan yang meningkat ialah: 166-167.5 eV untuk S=O dalam dimetil sulfoxida, 168.1 eV untuk S=O₂ dalam poli-sulfon, 168.4 eV untuk SO₃ dalam polistirena sulfonat dan 168.8 eV untuk SO₄ dalam kondroitin sulfat. BE untuk puncak P2p daripada sebatian fosforus menunjukkan bacaan berikut: 132.9 eV untuk PO₃ dalam tri-isopropil fosfit, 133.3 eV untuk PO₄ dalam fosfat gliserol, 133.5 eV untuk PO₄ dalam natrium tripolifosfat dan 134.0 eV untuk PO₄ dalam natrium hexametafosfat. Keputusan ini menunjukkan bahawa hanya ada peningkatan yang kecil dalam tenaga pengikat (eV) apabila atom oksigen ditambah kepada sebatian yang diikat oleh S-O. Keputusan yang sama diperoleh apabila persekitaran oksigen atau poli-fosfat keempat ditambah kepada sebatian fosforus. Nilai BE untuk sebatian sulfur dan fosforus ini adalah berguna untuk para penyelidik yang cuba mengenal pasti sebatian yang lazim terdapat di atas permukaan dan antara-muka untuk aplikasi seperti bio-bahan, super-kapasitor dan mangkin.

 

Kata kunci: Fosforus; keadaan pengoksidaan; spektroskopi fotoelektron sinar-x; sulfur; tenaga pengikat

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*Pengarang untuk surat-menyurat; email: kimsiow@ukm.edu.my