Fuel-free micro/nanomotors as adsorptive platforms for water treatment

Micro/nanomotors (MNMs), which can actively move in fluid environments via self-propulsion, have emerged as a powerful platform for environmental remediation. Among them, fuel-free micro/nanomotors (FMNMs) are gaining particular attention due to their biocompatibility, long operational lifetime, and compatibility with real-world water treatment conditions. This review focuses on the emerging paradigm of FMNMs as active adsorbents, where autonomous motion overcomes the diffusion limitations of conventional passive adsorption systems, thereby enhancing pollutant capture efficiency. We summarize representative applications of FMNMs in removing a broad spectrum of pollutants and organize this discussion within a three-level framework, progressing from dynamic adsorption for accelerating mass transfer, to multifunctional adsorption for integrating detection and degradation of pollutants, and finally to advanced adsorption for adaptive and collective pollutant removal. Looking ahead, we outline both engineering and fundamental research directions for advancing FMNMs toward practical implementation. We hope this review can stimulate interdisciplinary collaborations to address the fundamental challenges in adsorption-based pollutant removal and to advance the application of fuel-free micro/nanomotors for water purification.