To improve the performance of solar energy-driven water generation, two-dimensional (2D) photothermal materials requisite to be optimized by some strategies such as alloying, combination of plasmonic and defect modulation. However, the challenges faced in practical utilization are the complex preparation process and insufficient solar spectrum absorption. Herein, we propose a strategy of self-enhancing photothermal performance induced by topological surface states (TSSs). 2D WTe₂ is fabricated on the mixed cellulose ester (MCE) for photothermal device. Compared to the MCE and pure water, WTe₂ @MCE has an excellent photothermal evaporation rate of 1.09 kg·m⁻²·h⁻¹ upon 1 sun irradiation, promoting 6.1 and 3.1 times, respectively. It can be attributed to the characteristics of 2D Weyl semimetal WTe₂ with TSSs bringing about high optical absorption capacity, low thermal diffusivity, specific heat capacity, and high carrier density, which are strongly proved by experiments and calculation. More importantly, the contribution of TSSs to the enhancement of optical absorption for efficient solar water generation is revealed by the comparative experiment between 2D WTe₂ with TSSs and that without TSSs. Furthermore, photothermal conversion mechanism is explored in-depth understanding that the photoexcited electrons recombinate with the holes through nonradiative mode for releasing thermal energy by phonons emission via multiple pathway. This work promotes the application of Weyl semimetal material with TSSs in solar water evaporation.

Sub-nanometer armchair graphene nanoribbons (GNRs) with moderate band gap have great potential towards novel nanodevices. GNRs can be synthesized in the confined tubular space of single-walled carbon nanotubes (SWCNTs), in which precursor molecules have been specifically designed to form the GNRs with certain width and edge. However, it is still unexplored how the diameter and metallicity of SWCNTs influence the synthesis of the GNRs. Herein, we applied a series of SWCNTs with different average diameters to study the diameter-dependent synthesis of GNRs. By using Raman spectroscopy and transmission electron microscopy, we found that the width of the GNRs can be tailored by the diameter of the SWCNTs. Especially, the SWCNTs with average diameter of 1.3 nm produced 6 and 7 armchair GNRs with the highest yield, which can be well explained by considering the width of the GNRs and van der Waals radius of hydrogen and carbon atoms. In addition, semiconducting and metallic SWCNTs produced GNRs with different yields, which could attribute to different diameter distributions and density of defects. These results enable the possibility of a high-yield production of certain armchair graphene nanoribbons in large scale, which would benefit future applications as semiconductor with sub-nanometer in width.