Porous single-crystalline titanium dioxide at 2 cm scale delivering enhanced photoelectrochemical performance.

Porous single-crystalline (P-SC) titanium dioxide in large size would significantly enhance their photoelectrochemical functionalities owing to the structural coherence and large surface area. Here we show the growth of P-SC anatase titanium dioxide on an 2 cm scale through a conceptually different lattice reconstruction strategy by direct removal of K/P from KTiOPO4 lattice leaving the open Ti-O skeleton simultaneously recrystallizing into titanium dioxide. The (101) facet dominates the growth of titanium dioxide while the relative titanium densities on different parent crystal facets control the microstructures. Crystal growth in reducing atmospheres produces P-SC TinO2n-1 (n = 7~38) in magneli phases with enhanced visible-infrared light absorption and conductivity. The P-SC TinO2n-1 shows enhanced exciton lifetime and charge mobility. The P-SC TinO2n-1 boosts photoelectrochemical oxidation of benzene to phenol with P-SC Ti9O17 showing 60.1% benzene conversion and 99.6% phenol selectivity at room temperature which is the highest so far to the best of our knowledge.