Flexible vacancy-mediated MoS2-x nanosheet arrays for solar-driven interfacial water evaporation, photothermal-enhanced photodegradation, and thermoelectric generation

Highlights: • Vertically aligned MoS_2-x nanosheet arrays were in situ grown on Mo meshes. • The positive impact of interfacial heat on photocatalysis was proved. • 3D solar absorber led to 0.45 kg m^–2h⁻¹ enhancement in evaporation rate. • Continuous power generation was achieved by the MoS_2-x nanosheet arrays. Integrating new functionalities into solar-driven interfacial evaporation systems has received considerable attention. Herein, a high solar energy utilization system was accomplished by using vertically aligned MoS_2-x nanosheet arrays with S vacancies (MoS_2-x NSAs) in situ grown on Mo meshes as solar absorbers. In this system, interfacial heat was used to drive water evaporation and photothermal-enhanced photodegradation, and the produced waste low-grade heat was converted to electricity simultaneously. The MoS_2-x NSAs possessed a solar absorptance of 94.2%, favorable photothermal conversion, and heat localization properties. The localized heat and S vacancies collaboratively improved the photodegradation performance by boosting the separation of photogenerated carriers, which avoided dye accumulation on the surface of the MoS_2-x NSAs during a long-term operation. Furthermore, the solar absorber with flexible and shape adaptiveness was greatly feasible for enhancing solar evaporating performance or integrating different functionalities. Specifically, a 0.45 kg m^–2h⁻¹ increase in evaporation rate was achieved by the three-dimensional (3D) U-shaped MoS_2-x NSAs in comparison with the two-dimensional (2D) counterpart. And the 3D U-shaped MoS_2-x NSAs coupled with a thermoelectric module could uninterruptedly convert waste heat to electricity all day. This study successfully introduced photocatalysis and light-induced thermoelectricity into state-of-art solar-driven interfacial evaporation systems, which broadened this technology's application.