Time-dependent chemical vapor deposition growth of three-dimensional graphene on carbon fiber fabric for efficient electricity harvesting from water evaporation

Harvesting electricity from natural water evaporation has emerged as a promising alternative to realize the environmental energy conversion directly and sustainably. However, most reported water evaporation-induced electric generators (WEIGs) still involve a tedious preparation process and exhibit a low electric output, which hinders their practical applications. In this study, a facile fabrication of WEIG by depositing three-dimensional (3D) graphene on carbon fiber (CF) fabric by plasma-enhanced chemical vapor deposition (PECVD) was developed. By simply modulating the growth time during PECVD process, the precise control of crystalline quality, chemical bonding, morphology and electrical conductivity of 3D graphene/CF composite fabric was fulfilled. Benefited from the favorable structure with high specific surface area, small nanochannel size and large oxygen content, the 3D graphene/CF composite fabric-based WEIG prepared for 60 min presented a champion output of 0.78 V, 43.36 μA cm⁻² and 10.93 μW cm⁻², which exceeds those of reported WEIGs. The prominent electrokinetic effect was attributed to the high zeta potential for efficient surface charge generation, the large electron double layer overlap for significant counter ions induction and the good conductivity for facile electrical conduction. This work paves a new alternative way for material construction toward efficient and sustainable electricity harvesting from environment.