Inorganic hydrogen-bonded SnO(OH)2 as molecular springs boosted the piezocatalytic degradation of contaminants

Abstract

The achievement of highly active and stable piezocatalysts is still challenging for the efficient transformation of mechanical energy to chemical energy. Herein various SnO_xH_y species were prepared by a simple precipitation–thermal treatment method and applied for the piezocatalytic degradation of tricyclazole. It is found that the catalytic activity depended on the thermal treatment and follows the order SnO(OH)₂ (80 °C) > SnO_2.55H_1.1 (200 °C) > SnO_2.3H_0.6 (300 °C) > SnO_2.22H_0.24 (400 °C) > SnO₂ (500 °C) > rutile SnO₂ (800 °C). SnO(OH)₂ (80 °C) boosted the degradation of tricyclazole and the reaction constant reached as high as 0.0354 min⁻¹, 7.1 fold that of SnO₂ (800 °C). The differences among these SnO_xOH_y piezocatalysts mainly stemmed from the dissimilarity of the relative content of SnO(OH)₂. In addition to the Sn–O piezoelectric motif, SnO(OH)₂ had rich hydrogen bond networks, which work like molecular springs under external pressure. Due to such a special structure, SnO(OH)₂ had not only a super high piezoelectric constant (d₃₃) of 409.1 pm V⁻¹ among the currently reported piezomaterials, but also a 0.49 eV-higher valence band than SnO₂, being beneficial to the generation of stronger oxidative ˙OH. This is the first example of inorganic hydrogen-bonded piezomaterials, which opens a new window to develop advanced piezocatalysts for highly efficient degradation of refractory pollutants by piezocatalysis.