<p>Chalcogenide-based semiconductors have advanced from laboratory curiosities to multifunctional platforms that now underpin water purification, gas conversion, sensor technology and solar-driven fuel generation. Recent surveys have examined these themes in isolation, concentrating either on photocatalysis or on single pollutant classes. The present review offers the first integrative analysis that links adsorption forces, band edge engineering and catalytic kinetics across the entire environmental value chain, drawing on multiple primary studies published between 2016 and 2025. Emphasis is placed on less explored selenides and tellurides, on stability-limiting photocorrosion pathways, and on the life-cycle and toxicity constraints that determine industrial viability. A unified set of activity units and performance descriptors is used to compare adsorption affinities, degradation quantum yields, gas reduction Faradaic efficiencies and sensor detection limits, thereby exposing the trade-offs that guide material selection. The review further distils how defect engineering, heterojunction construction, and cocatalyst loading simultaneously enhance charge separation, enlarge surface basicity and prolong catalyst lifetimes, with case studies that translate these principles into pilot-scale photoreactors and Internet of things (IoT)-enabled sensor arrays. By situating chalcogenides within a broader sustainability framework that includes green synthesis and end-of-life recovery, this article provides a comprehensive roadmap for researchers and engineers aiming to deploy these materials in next-generation environmental and renewable energy technologies.</p> Graphical abstract <p></p>