Ultrathin two-dimensional amorphous carbon sheets with surface nanowrinkles via liquid-phase synthesis for...

Ultrathin two-dimensional (2D) amorphous carbon sheets with sp²-sp³ hybridization, efficient charge transfer capabilities, and highly accessible porosity have shown great potential in ultrasensitive detection associated with human health. However, the controllable synthesis of structurally well-defined 2D amorphous carbons remains a significant challenge, hindering their practical applications. Here, we present a facile liquid-phase assembly strategy to fabricate free-standing carbon sheets featuring large lateral dimensions (∼55 μm), ultrathin thicknesses (8.7-13.4 nm), and in-situ engineered surface nanowrinkles. These unique characteristics facilitate direct patterning into monolayers and enable the development of a metal-free surface-enhanced Raman scattering (SERS) platform for trace detection of diverse organic pollutants. The intrinsic correlation between the 2D characteristics of amorphous carbon and its SERS performance is systematically elucidated. Consequently, the ultrathin structures exhibit 10-100-fold higher sensitivity than their bulk counterparts, owing to enhanced adsorption capability and more efficient charge-transfer pathways that synergistically amplify the SERS response. In addition, the geometrical surface nanowrinkles are further confirmed to facilitate electron release and thus improve detection performance. This work establishes a well-defined 2D amorphous carbon platform via a novel liquid-phase strategy, providing fundamental insights into structure-performance relationships and advancing the rational design of next-generation, cost-effective SERS materials.