Infrared active narrow bandgap Ni doped LaFeO3 nanoparticles for desalination and decontamination of water leveraging interfacial solar steam generation

Abstract

Photothermal Ni-doped LaFeO3 (NLFO) (LaFe1-xNixO3, x = 0, 0.2, 0.3, 0.4, and 0.5) microspheres composed of nanoparticles synthesized by hydrothermal method are utilized for interfacial solar steam generation (ISSG) of salty and contaminated water. The orthorhombic (pnma) to rhombohedral (R3c¯) phase transition of LaFeO3 (LFO) at morphotropic phase boundary (MPB) flattens the free energy profile, and high absorbance in the 800–2000 nm Vis-NIR region arises due to the creation of intra-band gap states are accountable for superior activity towards the ISSG for desalination. The La, Ni, and Fe possess the oxidation states of 3+, 2+, and 3+/4+, respectively, showing successful doping of Ni2+ at the Fe3+ sites that produce lattice distortion at La/FeO6 octahedra. LaFe0.5Ni0.5O3 (NLFO5) sample exhibits surface temperature of 50.4 °C due to heat localization and produces evaporation flux of 2.89 kg/m2h under IR illumination at the air-water interface. Importantly, NLFO5 loaded cellulose paper shows good repeatability and cyclic stability for 10 consecutive cycles under IR illumination and equivalent evaporation flux of 2.4 kg/m2h under direct sunlight illumination. Moreover, 3.5 wt% saline water shows a drastic decrement in ion concentration after ISSG, as confirmed by atomic absorption spectroscopy. Furthermore, NLFO5 possesses good evaporation flux of 2.27 and 2.20 kg/m2h for water contaminated with RhB and MB organic dye. Our results propose the NLFO as distinguished photothermal material for ISSG application and wastewater purification by means of evaporation.