This study investigates the effect of Ca²⁺ doping on the photocatalytic degradation of 4-Nitrophenol (4-NP) using AgInS₂ (AIS) under visible light. The researchers synthesized AIS and Ca-AIS with varying amounts of Ca²⁺ using a low-temperature liquid phase method. Characterization techniques such as SEM, XRD, XPS, HRTEM, BET, PL, and UV-Vis DRS were employed to analyze the structural, morphological, and optical properties of the materials. The results showed that Ca²⁺ doping improved the visible light catalytic activity of AIS. Under visible light illumination for 120 minutes, a degradation rate of 63.2% for 4-NP was achieved. The study suggests that appropriate Ca²⁺ doping can enhance the photocatalytic performance of AIS, making it a promising candidate for environmental applications. The findings provide insights into the potential use of cheap alkaline earth metal dopants to improve the photocatalytic activities of materials.This study investigates the effect of Ca²⁺ doping on the photocatalytic degradation of 4-Nitrophenol (4-NP) using AgInS₂ (AIS) under visible light. The researchers synthesized AIS and Ca-AIS with varying amounts of Ca²⁺ using a low-temperature liquid phase method. Characterization techniques such as SEM, XRD, XPS, HRTEM, BET, PL, and UV-Vis DRS were employed to analyze the structural, morphological, and optical properties of the materials. The results showed that Ca²⁺ doping improved the visible light catalytic activity of AIS. Under visible light illumination for 120 minutes, a degradation rate of 63.2% for 4-NP was achieved. The study suggests that appropriate Ca²⁺ doping can enhance the photocatalytic performance of AIS, making it a promising candidate for environmental applications. The findings provide insights into the potential use of cheap alkaline earth metal dopants to improve the photocatalytic activities of materials.