Enhanced photocatalytic performance of LaFeO3/g-C3N4 heterojunctions for the degradation of orange G dye under visible light

In this study, LaFeO3/g-C3N4 (LFO/g-CN) hybrid materials with mass ratios of LFO and g-CN of 1/0.5, 1/1, and 1/1.5 were synthesized and evaluated for the visible light photocatalytic degradation of the azo-dye Orange G (OG). The composite materials were characterized to determine their textural, morphological, and optical properties. Preliminary photocatalytic results highlighted a significant synergistic interaction between LFO and g-CN. The LFO/g-CN (1/1.5) composite exhibits the highest activity, achieving 50% OG removal, representing a 2.7-fold improvement over pristine g-CN, with a rate constant of 0.0048 min−1 (3.7 times higher than bare g-CN). The degradation kinetics follow a pseudo-first-order model. The influence of key operational parameters, including catalyst loading, initial pH, pollutant concentration, and visible-light intensity, was systematically investigated using the optimized LFO/g-CN (1/1.5) composite. Optimal OG conditions (0.5 g L−1 catalyst, pH 2.0, 10 mg L−1 OG concentration, 0.95 W cm−2 visible light intensity) yielded a maximum rate constant of 0.0119 min−1 and 82% OG decolorization after 135 min. At higher catalyst or dye concentrations, the photocatalytic activity declined due to light scattering and surface saturation. Enhanced OG degradation under acidic conditions was attributed to favourable electrostatic attraction between the positively charged catalyst surface and anionic OG moieties. The composite also demonstrated excellent stability, retaining over 77% of its initial activity after four reuse cycles. These findings highlight the potential of LFO/g-CN heterojunctions as efficient visible-light photocatalysts for sustainable water remediation.