Synthesis of transition metal doped lanthanum silicate oxyapatites by a facile co-precipitation method and their evaluation as solid oxide fuel cell electrolytes

Henri Joel Mbah Ngantchou; Rizwan Raza; Edwin Akongnwi Nforna; John Lambi Ngolui; Tauqir A Sherazi

doi:10.1039/d2ra07088j

Synthesis of transition metal doped lanthanum silicate oxyapatites by a facile co-precipitation method and their evaluation as solid oxide fuel cell electrolytes

RSC Adv. 2023 Apr 19;13(18):12285-12294. doi: 10.1039/d2ra07088j. eCollection 2023 Apr 17.

Authors

Henri Joel Mbah Ngantchou^{1

2}, Rizwan Raza³, Edwin Akongnwi Nforna⁴, John Lambi Ngolui⁵, Tauqir A Sherazi¹

Affiliations

¹ Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus Abbottabad 22060 Pakistan sherazi@cuiatd.edu.pk.
² Department of Chemistry, Faculty of Sciences, University of Douala P.O Box 24157 Douala Cameroon.
³ Department of Physics, COMSATS University Islamabad, Lahore Campus Lahore 54000 Pakistan razahussaini786@gmail.com.
⁴ Department of Fundamental Science, Higher Technical Teacher Training College, The University of Bamenda P.O. Box 39 Bambili Cameroon.
⁵ Chemistry Department, Higher Teacher Training College, University of Yaoundé I Yaoundé 47 Cameroon.

Abstract

Transition metal doped apatite La₁₀Si_6-x Co _x O_27-δ (x = 0.0; 0.2; 0.8) and La₁₀Si_5.2Co_0.4Ni_0.4O_27-δ are synthesized by co-precipitation method followed by sintering. The precursor precipitates and apatite products are characterized by XRD, FTIR, TGA/DTA, Raman Spectroscopy, SEM-EDX and electrochemical impedance spectroscopy. The presence of apatite phase with hexagonal structure is confirmed through the XRD results. The conductivity measurements of the samples sintered at 1000 °C show that the ionic conductivity increases with increasing content of Co²⁺ doping into apatite that is further increased by co-doping of Ni²⁺. The Co doped apatite (La₁₀Si_5.2Co_0.8O_27-δ ) exhibited conductivity of 1.46 × 10^-3 S cm^-1 while Co-Ni co-doped sample (La₁₀Si_5.2Co_0.4Ni_0.4O_27-δ ) exhibited highest conductivity of 1.48 × 10^-3 S cm^-1. The maximum power density achieved is also for Co, Ni co-doped sample i.e., 0.65 W cm^-2 at 600 °C. The results represented show that Co and Ni enhances the SOFC performance of apatite and makes it potential electrolyte candidate for solid oxide fuel cell application.