Efficient solar steam generation enabled by nanolamellar λ-Ti3O5 based on designing the bandgap through morphology modulation

Abstract

Solar steam generation has attracted wide interest in desalination and sewage purification due to its cost-effectiveness and environmental friendliness. However, the low evaporation rate and energy utilization efficiency limit the further application of the evaporation system. In order to solve the above problems, a lot of efforts have been made in the development of new materials. With excellent semiconductor properties and photothermal performance, titanium suboxides (Ti_nO_2n−1) are considered as promising materials used as the photothermal conversion materials (PTCMs). However, less emphasis is placed on how crucial it is to adjust the grain size of Ti_nO_2n−1 in order to design the bandgap and improve evaporation performance. Therefore, in this work, we report a pathway to modulate the grain size and morphology to prepare nanolamellar λ-Ti₃O₅ (NL-T3). The tuned λ-Ti₃O₅ has a narrower bandgap and can thus generate more electron–hole pairs under solar irradiation, with up to 92.2% solar absorptivity and 91.7% photothermal conversion efficiency. And the lamellar morphology has a remarkably high specific surface area of 131.3 m² g⁻¹, which makes NL-T3 have superior hydrophilicity. Its application in a structurally optimized 3D evaporation system achieved an evaporation rate of 6.41 kg m⁻² h⁻¹ and superior cycling performance under long-term use. This study emphasizes the importance of modulation of morphology for semiconductor PTCMs and provides a theoretical basis for their subsequent efficient application in the solar field.