Hybrid covalent organic frameworks: advanced material for critical metals recovery and other applications

The surging demand for critical metals (CMs)—driven by their pivotal role in renewable energy technologies—has intensified global supply chain vulnerabilities and environmental degradation, underscoring an urgent need for sustainable recovery strategies. To address this dual challenge of resource scarcity and ecological impact, sustainable recovery of CMs from liquid waste streams has emerged as a cost-effective and environmentally strategic alternative. While materials such as membranes, carbon-based adsorbents, and metal–organic frameworks (MOFs) have shown promise in CMs recovery, covalent organic frameworks (COFs) offer unique advantages, including tunable porosity, structural precision, and functional versatility. However, despite their transformative potential, the design, synthesis, and application of hybrid COF-based materials—engineered by integrating COFs with complementary functional components—remain underexplored. This review systematically addresses this gap by elucidating innovative design strategies for hybrid COFs (H-COFs) integrated with MOFs, magnetic nanoparticles, carbon nanomaterials (e.g., graphene oxide, carbon dots), membranes, and multilayer COFs architectures. We critically evaluate their unparalleled potential in CMs recovery through tailored porosity, selective binding sites, and enhanced stability while mapping their multifunctional applications in water purification, energy storage, catalytic systems, and sensor technologies. By correlating structural engineering with performance metrics, this review provides a blueprint for synthesizing next-generation H-COFs, bridging fundamental research with industrial scalability. Beyond advancing material science, the review establishes a cross-disciplinary framework to address pressing global challenges—from resource sustainability to clean energy transitions—positioning H-COFs as keystones in developing circular economies and high-performance technologies. This comprehensive analysis catalyzes future innovation in hybrid material design and aligns scientific progress with the United Nations Sustainable Development Goals (SDGs), emphasizing such research's societal and environmental imperative.