Bio-inspired polypyrrole nanowire arrays on melamine foam with high-performance photo/electro-thermal conversion for all-weather cleanup of crude oil

Abstract

The high viscosity and low fluidity of crude oil impede its adsorption by porous sorbents, making the effective cleanup of crude oil a significant challenge. Herein, inspired the nano-structure of moth eyes, we developed a hierarchical adsorbent material via electrochemically polymerizing polypyrrole nanowire arrays (PPy NWAs) onto melamine foam (MF), where 1D ordered PPy NWAs were vertically grown on the 3D MF skeleton. The aligned PPy NWAs enhanced hydrophobicity (water contact angle of 151.0°) and served as numerous capillary tubes, thereby achieving 81.0 g/g oil adsorption. Due to the continuous PPy network, the MF@PPy foams exhibited remarkable light-trapping effect with a high light absorption ration of 98.8% and good electrical conductivity of 201 S/m. The surface temperature could quickly reach 85.5 °C under simulated illumination (1 sun) and 88.1 °C with a power input (2 V). Interestingly, the photothermal and superhydrophobic effects induced Marangoni flow that leaded to controllable light-driven motion. Furthermore, the MF@PPy foams could be remotely operated, allowing for the sustained removal of crude oil from water surfaces via light-activated and pump-assisted systems. This work provides new insights for developing oil adsorption materials by constructing moth-eye structured PPy NWAs, demonstrating great potential for all-weather crude oil adsorption.