Active Adsorption Materials: A Review of Smart Sorbents for Environmental and Energy Applications

Abstract

Active adsorption materials smart sorbents that dynamically respond to external stimuli are revolutionizing conventional strategies in environmental remediation and energy storage. Unlike traditional passive adsorbents, these advanced materials exhibit tunable physicochemical properties
that can be selectively activated or modulated by variations in temperature, pH, light, electric fields, or magnetic fields. This stimuli-responsive behavior offers significant advantages, including enhanced selectivity, reversible adsorption, energy-efficient regeneration, and real-time adaptability to changing operational conditions. As a result, active adsorbents are increasingly being integrated into cutting-edge applications such as water purification, gas separation, air filtration, and carbon dioxide capture. This review provides a comprehensive and structured analysis of the current landscape of active adsorption materials. The discussion is organized around the types of stimuli used to trigger adsorption mechanisms, the classes of materials employed including metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), nanocomposites, and responsive polymers and the specific application domains where these materials demonstrate the most promise. Particular attention is given to how molecular architecture, pore structure, and surface chemistry influence performance under external stimuli. Additionally, the review highlights recent advances in fabrication and functionalization techniques that have enabled the precise engineering of stimuli-responsive sites and dynamic frameworks. Key examples from experimental studies and scalable prototypes are analyzed to illustrate the state-of-the-art. The mechanisms underlying adsorption responsiveness such as conformational switching, charge modulation, and photothermal transformation are also examined to elucidate how these materials achieve targeted performance. Despite their potential, challenges remain regarding long-term stability, material toxicity, cost-effective synthesis, and integration into industrial-scale systems. The review concludes by identifying future research directions, emphasizing the need for interdisciplinary approaches that blend materials science, environmental engineering, and nanotechnology to overcome existing limitations and unlock the full potential of smart sorbents in sustainable technologies.