Graphene meshes (GMs) have attracted considerable attention as advanced materials for high-performance gas sensing due to their high-density active edge sites and excellent electronic properties. However, the contamination-free preparation of GMs remains a challenge. Herein, we present a dewdrop-templated chemical vapor deposition approach to directly grow clean and intact graphene micromeshes (GMM) on SiO₂/Si substrates. The self-assembled micrometer-sized dewdrops from controlled water vapor condensation serve as a residue-free template for directing the growth of GMM with tunable hole sizes from submicrons to tens of microns. Density functional theory (DFT) calculations reveal that carbon species preferentially adsorb on pristine SiO₂ regions to form a mesh structure. Contamination-free GMM gas sensors were fabricated using a simple transfer-free process, demonstrating a record-high sensitivity of 7.25 %·ppm⁻¹ and an ultra-low detection limit of 1.18 ppb for NO₂ at room temperature. Complementary DFT studies elucidate that NO₂ molecules adsorb more strongly on the edges of GMM, leading to a high response of the sensor. This work offers profound insights into dewdrop-templated graphene growth mechanisms and establishes a simple yet effective approach for fabricating high-performance transfer-free GMM sensors, thus paving the way for their practical applications in environmental monitoring and industrial safety fields.

Graphene-based flexible transparent electrodes (FTEs) are promising candidate materials for developing next-generation flexible organic light-emitting diodes (OLEDs). However, the quest for high-efficiency OLEDs is hindered by the low light-extraction and charge injection efficiencies of graphene electrode. Here, we combine the frustrated Lewis pair doping with nanostructure engineering to obtain high-performance graphene FTE. A p-type dopant aci-nitromethane-tris(pentafluorophenyl) borane (ANBCF) was synthesized and deposited on graphene FTE to form an aperiodic nanostructure, which not only improves the light-extraction but also stably p-dopes graphene to enhance its hole injection. The use of ANBCF-doped graphene as the anode enables high-efficiency flexible green OLEDs with external quantum efficiency (EQE) and power efficiency (PE) out-performing most flexible graphene OLEDs of comparable structure. This study provides a simple and effective pathway to fabricate high-performance graphene FTEs for efficient flexible OLEDs.

We report a facile approach to synthesize narrow and long graphene nanoribbons (GNRs) by sonochemically cutting chemically derived graphene sheets (GSs). The yield of GNRs can reach ~5 wt% of the starting GSs. The resulting GNRs are several micrometers in length, with ~75% being single-layer, and ~40% being narrower than 20 nm in width. A chemical tailoring mechanism involving oxygen-unzipping of GSs under sonochemical conditions is proposed on the basis of experimental observations and previously reported theoretical calculations; it is suggested that the formation and distribution of line faults on graphite oxide and GSs play crucial roles in the formation of GNRs. These results open up the possibilities of the large-scale synthesis and various technological applications of GNRs.