Research Article Design of Sm-doped GdFeO 3 /g-C 3 N 4 heterostructure Z-scheme photo-catalyst for the elimination of malachite green dye from industrial water Firdous Bibi a , Muhammad Jamshaid b , Wedad A. Al-onazi c , Ambreen Kalsoom a,* , Mohammad Ashraf Hossain d , Rashid Iqbal e,f , Mohamed S. Elshikh g , Shahid Iqbal b,** a Department of Physics, The Govt Sadiq College Women University Bahawalpur, 63100, Pakistan b Institute of Chemistry, The Islamia University of Bahawalpur, 63100, Bahawalpur, Pakistan c Department of Chemistry, College of Science, King Saud University, P.O. Box 22452, Riyadh, 11495, Saudi Arabia d School of Materials Science and Engineering Tongji University, China e Department of Agronomy, Faculty of Agriculture and Environment, The Islamia University of Bahawalpur, 63100, Pakistan f Department of Life Sciences, Western Caspian University, Baku, Azerbaijan g Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia A R T I C L E INFO Keywords: Gd-orthoferrite Co-precipitation route Single phase Toxic pollutants Photo-degradation Malachite green dye ABSTRACT Herein, a highly efficient visible light-driven Sm-doped GdFeO 3 @g-C 3 N 4 heterostructure-based Z-scheme pho- tocatalyst was fabricated for the effective removal of malachite green (M.G) dye from the hazardous environ- mental pollutants. The structural study demonstrated the formation of the single-phase perovskite structure with the successful doping of Sm ions in the orthorhombic GdFeO 3 structure. The morphological investigation of Sm- doped GdFeO 3 @g-C 3 N 4 via SEM revealed the spiky rounded spherical structure having heterogeneous morphology. The Sm-doped g-C 3 N 4 nanocomposites (NC) based catalyst materials demonstrated the enhanced BET surface areas (36, 79 and 109 m 2 /g for GdFeO 3 NF, Sm-doped Gd 1-x Sm x FeO 3 nanoferrites (NFs) and Gd 1- x Sm x FeO 3 @g-C 3 N 4 nanocomposite) with well-porous structures. The improved electrical conductivity values, were noticed as 3.15 × 10  5 S/m, 4.24 × 10  3 S/m, and 96.08 S/m, for GdFeO 3 nanoferrites, Sm-doped Gd 1- x Sm x FeO 3 nanoferrites and Gd 1-x Sm x FeO 3 @g-C 3 N 4 nanocomposite respectively. The vibrating-sample magne- tometry (VSM) analysis exhibited the enhancement in magnetic characteristics of GdFeO 3 nanoferrite, Sm-doped Gd 1-x Sm x FeO 3 nanoferrites and Gd 1-x Sm x FeO 3 @g-C 3 N 4 nanocomposite i.e., saturation magnetization 0.81 to 0.93, and 0.99 emu/g, because of Sm-doping attributed to the larger magnetic moment of Sm ions. The nar- rowing of Egs values was noticed from 2.21, 2.07, and 2.02 (eV) for GdFeO 3 NF, Sm-doped Gd 1-x Sm x FeO 3 nanoferrites, and Gd 1-x Sm x FeO 3 @g-C 3 N 4 nanocomposites, respectively. The photo-degradation studies of syn- thesized catalysts were estimated by removing M.G dye under the natural sunlight irradiation. The Gd 1- x Sm x FeO 3 @g-C 3 N 4 nanocomposite demonstrated the superior elimination of M.G dye as 93.92 % within 70 min as compared to Gd 1-x Sm x FeO 3 nanoferrites and GdFeO 3 nanoferrite, which remove 71.45 % and 34.78 % of M.G dye. 1. Introduction All the living things including human and aquatic life are adversely impacted by synthetic organic colorants, which are discharged into water bodies from different industrial sources, including paper printing, textiles, dyeing, and cosmetics, without undergoing appropriate purification. These colorants are associated with multiple health issues, i.e., skin irritation and skin cancer, and adversely affect the respiratory, digestive, and neurological systems. Due to their hazardous impacts on living organisms, the eradication of these synthetic pollutants is crucial for maintaining an eco-friendly environment. Currently, many research studies have been adopted on the photo-catalytic oxidation procedures, * Corresponding author. ** Corresponding author. E-mail addresses: kalsoom.ambreen@gscwu.edu.pk (A. Kalsoom), Shahidiqbal0102@gmail.com (S. Iqbal). Contents lists available at ScienceDirect Optical Materials journal homepage: www.elsevier.com/locate/optmat https://doi.org/10.1016/j.optmat.2025.116696 Received 28 October 2024; Received in revised form 9 December 2024; Accepted 15 January 2025 Optical Materials 160 (2025) 116696 Available online 18 January 2025 0925-3467/© 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.