β‑SnWO₄ Photocatalyst with Controlled Morphological Transition of Cubes to Spikecubes

A distinct morphology of β-SnWO₄ with hierarchically multiarmed architecture and overall hexahedral symmetry – entitled as spikecube – is fabricated for the first time via a polyol-mediated synthesis. The growth of the β-SnWO₄ spikecubes is investigated and attributed to thermodynamic and kinetic control. In a sequential reaction, crystalline cubes of β-SnWO₄ enclosed by {100} facets grow in a first Ostwald ripening-based step. A kinetically controlled growth process to spikecubes follows under formation of multiarmed spikes on the facets of the cubic seeds. Such a growth process differs significantly from the literature concerning highly branched crystals. The synergistic effect of morphological modification (i.e., introducing more surface reaction sites) and textural alteration (i.e., incorporation of the p-block Sn²⁺ into simple tungsten oxide to reframe its band structure) leads to an enhanced photocatalytic activity of the β-SnWO₄ spikecubes being 150% higher in comparison to benchmark WO₃ photocatalysts.