S.N. Manjula^1,2,, M. Chandrasekhar^2,*,, M.R. Anil Kumar^3,, N. Raghavendra^2,, C.R. Ravikumar^2,*,, H.C. Ananda Murthy^4,5, and H. Nagabhushana^6,

¹Department of Physics, SJR College for Women, Rajajinagar, Bengaluru-560010, India

²Research Center, Department of Science, East West Institute of Technology, (Affiliated to Visvesvaraya Technological University), Bangalore-560091, India

³Department of Chemical and Materials Engineering, Gina Cody School of Engineering and Computer Science, Concordia University, Montreal, Canada, H3G 2W1

⁴Department of Applied Chemistry, School of Applied Natural Science, Adama Science and Technology University, PO Box 1888, Adama, Ethiopia

⁵Department of Prosthodontics, Saveetha Dental College & Hospital, Saveetha Institute of Medical and Technical Science (SIMATS), Saveetha University, Chennai-600077, India

⁶Prof. C.N.R. Rao Center for Advanced Materials, Tumkur University, Tumkur-572103, India

*Corresponding authors: E-mail: mcshekar7@gmail.com; ravicr128@gmail.com

Ho³⁺-doped MgAl₂O₄ nanophosphors (1-11 mol%) was synthesised via solution combustion method using oxalyl dihydrazide (ODH) as fuel. The findings revealed a range of band gap energies (E_g) between 4.86 and 5.42 eV. It was confirmed that these values correspond extremely well with the experimental data using the DFT approach. The Ho³⁺ ions in the host undergo f-f transitions that are triggered at 406 nm and as a result, exhibit discrete photoluminescence emission peaks between 406 and 605 nm. Enhanced MgAl₂O₄ have CIE coordinates from orange-red to yellow region and 97% colour purity. Photocatalytic properties of nanophosphors under UV light led to the discovery that a rapid orange-red dye is activated at 493 nm. Removal of fast orange red (F-OR) dye using the new photocatalysts and MgAl₂O₄:Ho³⁺ nanophosphors has been demonstrated. The investigation showed that 89.02% of the dye lost its colour after being exposed to radiation for 120 min. The modified MgAl₂O₄:Ho³⁺ carbon paste electrode used in the cyclic voltametric (CV) technique for lead pollution detection. Based on their electrochemical performance, it is concluded that MgAl₂O₄:Ho³⁺ nanophosphors are a viable material for lead detecting electrodes.

Nanophosphors, MgAl₂O₄:Ho³⁺, Solution combustion, Fast orange red dye, Photocatalysis, Electrochemical sensor.