Crystal Facet Engineering on SrTiO3 Enhances Photocatalytic Overall Water Splitting

Single-crystal semiconductor-based photocatalysts exposing unique crystallographic facets show promising applications in energy and environmental technologies; however, crystal facet engineering through solid-state synthesis for photocatalytic overall water splitting is still challenging. Herein, we develop a novel crystal facet engineering strategy through solid-state recrystallization to synthesize uniform SrTiO3 single crystals exposing tailored 111 facets. The presynthesized low-crystalline SrTiO3 precursors enable the formation of well-defined single crystals through kinetically improved crystal structure transformation during solid-state recrystallization process. By employing subtle Al3+ ions as surface morphology modulators, the crystal surface orientation can be precisely tuned to a controlled percentage of 111 facets. The photocatalytic overall water splitting activity increases with the exposure percentage of 111 facets. Owing to the outstanding crystallinity and favorable anisotropic surface structure, the SrTiO3 single crystals with 36. 6% of 111 facets lead to a 3-fold enhancement of photocatalytic hydrogen evolution rates up to 1. 55 mmol·h–1 in a stoichiometric ratio of 2: 1 than thermodynamically stable SrTiO3 enclosed with isotropic 100 facets.