Bimetallic sulfide catalysts photocatalytically reduce carbon dioxide into high-value fuels: A review

Abstract

With the growing concerns over global climate change and rising energy demands, environmental challenges linked to carbon dioxide (CO₂) emissions have gained significant visibility. Converting CO₂ into high-value fuels not only helps mitigate the greenhouse effect but also facilitates the reuse of carbon resources. Among available conversion approaches, photocatalytic CO₂ reduction has drawn interest for relying on solar energy and operating through a green process. Bimetallic sulfide catalysts stand out in this context, offering distinct advantages including broad visible-light absorption, adjustable electronic properties, and plentiful surface-active sites. This review systematically surveys recent developments in bimetallic sulfide photocatalysts applied to CO₂ reduction. It clarifies fundamental structure-property correlations in representative materials including ZnIn₂S₄, CuInS₂, and CdIn₂S₄, illustrating how synergistic interactions between metal components direct their optoelectronic performance. This review scrutinizes the complex reaction mechanisms leading to products such as CO, CH₄, and C₂H₅OH, with particular emphasis on the role of sulfur vacancies and surface configurations in activating inert CO₂ molecules. Furthermore, it delineates methodologies for boosting photocatalytic efficiency, including structural and morphological control, defect engineering, constructing heterojunctions, and cocatalyst loading. This work concludes by identifying prevailing limitations and promising avenues within this dynamic research domain. Intended as a foundational guide, this review aims to serve as a foundational reference for the rational design of efficient and selective bimetallic sulfide catalysts toward solar-driven CO₂ valorization.