Photocatalytic self-propelled N/Se-codoped resin nanomotors for selective and sustainable palladium recovery

A photocatalytic self-propelled nanomotor adsorbent was developed for Pd(II) recovery. • Self-propulsion overcomes diffusion-limited adsorption kinetics. • EPR reveals the ROS-mediated mechanism of long-term propulsion. • Selective Pd(II) recovery is achieved in complex acidic wastewater. The recovery of palladium (Pd) from complex acidic industrial wastewater is severely restricted by sluggish interfacial mass transfer and inherent diffusion-limited adsorption kinetics. To address this long-standing bottleneck, asymmetric N/Se-codoped resorcinol-formaldehyde nanomotors (Se-RF@NMs) were rationally fabricated via an emulsion-confined anisotropic growth strategy for photocatalytic self-propulsion-boosted Pd(II) recovey. Under light irradiation, the photoresponsive resin framework enables continuous in-situ H 2 O 2 generation. Meanwhile, the adsorption-induced in-situ reduction of Pd(II) further accelerates catalytic H 2 O 2 decomposition to generate oxygen microbubbles, endowing nanomotors with sustainable autonomous motion and dynamically promoting interfacial ion transport. EPR characterization confirms that photogenerated holes and reactive oxygen species sustain the cyclic H 2 O 2 generation-decomposition system, effectively stabilizing the self-propulsion behavior of Se-RF@NMs. Benefiting from the synergistic coupling of photocatalytic self-propulsion and N/Se-based selective coordination adsorption, the optimized Se-RF@NMs achieve a superior Pd(II) adsorption capacity of 196.75 mg g −1 , as well as excellent selectivity in multi-metal competitive systems and practical industrial wastewater matrices. This work elucidates a photocatalysis-driven active mass transfer enhancement mechanism, establishing a feasible paradigm to break the intrinsic diffusion limitation of conventional adsorption. It provides new insights into the rational design of intelligent self-propelled catalytic adsorbents for high-efficiency precious metal recovery in complex and harsh water environments. Download: Download high-res image (152KB) Download: Download full-size image