Neodymium-Doped Novel Barium Tungstate Nanospindles for the Enhanced Oxygen Evolution Reaction

Srinivasan Swathi; Marimuthu Priyanga; Yuvakkumar Rathinam; Ravi Ganesan; Abdullah G Al-Sehemi; Dhayalan Velauthapillai

doi:10.1021/acsomega.2c05156

Neodymium-Doped Novel Barium Tungstate Nanospindles for the Enhanced Oxygen Evolution Reaction

ACS Omega. 2023 Jan 17;8(4):3745-3754. doi: 10.1021/acsomega.2c05156. eCollection 2023 Jan 31.

Authors

Srinivasan Swathi¹, Marimuthu Priyanga¹, Yuvakkumar Rathinam¹, Ravi Ganesan^{1

2}, Abdullah G Al-Sehemi³, Dhayalan Velauthapillai⁴

Affiliations

¹ Department of Physics, Alagappa University, Karaikudi, Tamil Nadu630 003, India.
² Adjunct Professor, Department of Physics, Chandigarh University, Mohali, Punjab140 413, India.
³ Department of Chemistry, King Khalid University, Abha61413, Saudi Arabia.
⁴ Faculty of Engineering and Science, Western Norway University of Applied Sciences, Bergen5063, Norway.

Abstract

In this work, pristine, 0.02, 0.04, and 0.06 M neodymium (Nd)-doped barium tungstate nanostructures were synthesized via a simple co-precipitation method for the water oxidation process. The obtained X-ray diffraction high-intensity peak at a 2θ value of 26.4° corresponding to the (112) lattice plane confirmed the formation of a tetragonal structure of BaWO₄. Moreover, the BaWO₄ morphology was examined by scanning electron microscopy, which showed the existence of nanospindles. An energy-dispersive X-ray spectrum confirmed the subsistence of the produced materials, for example, barium (Ba), tungsten (W), oxide (O), and neodymium (Nd), with weight percentages of 28.58, 46.63, 16.64, and 8.16%, respectively. The 0.04 M Nd-doped BaWO₄ product was explored to attain a high surface area of 18.18 m²/g, a pore volume of 0.079 cm³/g, and a pore diameter of 2.215 nm. Compared to the other prepared electrodes, the 0.04 M Nd-doped BaWO₄ product exhibited low overpotential values of 330 mV and 450 mV to deliver current densities of 10 mA/cm² and 50 mA/cm², respectively. In addition, the optimized electrode achieved a small Tafel slope value of 158 mV dec^-1 and followed the Volmer-Heyrovsky mechanism. Moreover, the electrical conductivity of BaWO₄ was tuned due to the addition of a rare-earth metal dopant, and it exhibited the charge-transfer resistance and solution resistance values of 0.98 and 1.01 Ω, respectively. The prepared electrocatalyst was further studied by using cyclic voltammetry, and it exhibited a high double-layer capacitance value of 29.3 mF/cm² and high electrochemically active surface areas of 1.465 cm². The electrochemical performance was greatly improved depending on the concentration of the doping agent, and it was well consistent with the obtained results. The best electrocatalyst was subjected to a chronoamperometry test, which exhibited excellent stability even after 20 h. Hence, this work suggests that alkaline metal tungstates have a cost-effective, efficient, and promising electrocatalyst, and it is a new approach for the water oxidation process.