Developing a low-carbon, scalable strategy for the conversion of spent batteries into metal-organic framework-74 for CO2 capture

Abstract

The growing demand for upgraded electronic products has resulted in a significant amount of waste batteries. In this paper, we propose a low-carbon, scalable mechanochemical waste-to-value strategy to convert spent ZnO from alkaline batteries into Zn-MOF-74, a functional metal–organic framework (MOF), for CO2 capture. The conversion pathway of ZnO-to-MOF-74 was investigated via structural characterization techniques. Compared with commercial ZnO with a hexagonal prism-like morphology, spent ZnO, exhibiting a rod-shaped morphology, demonstrated greater readiness in transforming into Zn-MOF-74, completing the transformation in nearly 5 h via ball milling and reducing energy consumption by around 50%. Moreover, the CO2 adsorption capacity of Zn-MOF-74 synthesized using spent ZnO, which is 2.07 mmol/g (at 273 K), is nearly triple that synthesized from commercial ZnO that has a hexagonal prism-shaped morphology. Overall, this study highlights the potential of repurposing spent ZnO in waste valorization, thereby significantly contributing to the advancement of a circular economy.