Flatband λ-Ti3O5 towards extraordinary solar steam generation.

Solar steam interfacial evaporation represents a promising strategy for seawater desalination and wastewater purification owing to its environmentally friendly character1-3. To improve the solar-to-steam generation, most previous efforts have focused on effectively harvesting solar energy over the full solar spectrum4-7. However, the importance of tuning joint densities of states in enhancing solar absorption of photothermal materials is less emphasized. Here we propose a route to greatly elevate joint densities of states by introducing a flat-band electronic structure. Our study reveals that metallic λ-Ti3O5 powders show a high solar absorptivity of 96.4% due to Ti-Ti dimer-induced flat bands around the Fermi level. By incorporating them into three-dimensional porous hydrogel-based evaporators with a conical cavity, an unprecedentedly high evaporation rate of roughly 6.09 kilograms per square metre per hour is achieved for 3.5 weight percent saline water under 1 sun of irradiation without salt precipitation. Fundamentally, the Ti-Ti dimers and U-shaped groove structure exposed on the λ-Ti3O5 surface facilitate the dissociation of adsorbed water molecules and benefit the interfacial water evaporation in the form of small clusters. The present work highlights the crucial roles of Ti-Ti dimer-induced flat bands in enchaining solar absorption and peculiar U-shaped grooves in promoting water dissociation, offering insights into access to cost-effective solar-to-steam generation.

Influences of hole/electron-lattice coupling on phase transition between λ-Ti3O5 and ß-Ti3O5.

The phase transition between λ-Ti3O5 and ß-Ti3O5 is an intriguing process that can be driven in multiple ways. However, the phase transition has not been reasonably and universally analyzed in atomic-scale, because it is limited by experimental inaccessibility. Here, the nudged elastic band method, crystal orbital Hamiltonian population integral calculation, phonon calculation, and electron (or hole) doping calculation are used to investigate the phase transition between λ-Ti3O5 and ß-Ti3O5. The atomic displacement mode in the phase transition between the ß-Ti3O5 and λ-Ti3O5 is provided, and a theory that the coupling between the lattice and excited electrons (or holes) is responsible for the phase transition between λ-Ti3O5 and ß-Ti3O5 is established.