Enhancing interfacial solar-driven evaporation and hydrovoltaic electricity generation by porous carbon nanoparticles from waste polyester

Abstract

Solar energy collection through the natural process of water evaporation for interfacial evaporation and electricity generation has emerged as a promising method for freshwater and electricity co-generation. However, it remains a challenge to develop a high-performance porous carbon nanomaterial-based multifunctional evaporator. Herein, we propose the green synthesis of porous carbon nanoparticles (PCN) through the pyrolysis of a calcium-based metal–organic framework derived from waste polyester and prepare PCN evaporators for freshwater and electricity co-generation. The PCN-based evaporator is characterized by low evaporation enthalpy, excellent photothermal conversion, effective sunlight absorption, abundant functional groups, and rich pore channels. It achieves a large evaporation rate of 2.32 kg m⁻² h⁻¹, voltage output of 0.33 V, and current of 7 µA under 1 Sun irradiation. The rich pore channels, large specific surface area, and abundant functional groups are proven to be crucial factors for the generation of electricity, which are indispensable for promoting high-voltage output. Furthermore, radial distribution function analysis reveals the voltage formation mechanism; that is, more Na⁺ ions in the solution migrate directionally under the traction of negative charges derived from functional groups in the nanochannels. This study provides a novel method for the green synthesis of porous carbon nanomaterials and contributes to the development of multi-functional evaporators for freshwater-electricity co-generation.