Gas-liquid interface derived lightweight and twistable BiOI/In2O3/tape assembly for photocatalytic NO removal

Mimicking the movement of leaves in response to external stimulations is inspiring for designing photocatalyst system applicable in space- and weight-sensitive scenarios. Here, we demonstrate that by combining a novel gas–liquid film growth process with a tape assisted film transfer procedure driven by capillary force, a lightweight and twistable photocatalyst assembly can be easily constructed. Taking the gas–liquid interface as a solute transfer boundary to selectively trigger the film growth at the interface, BiOI and BiOI/In 2 O 3 thin films up to 15 cm in diameter can be grown at a solution surface. Thanks to the capillary force present at the dynamic contact front during the film pick-up procedure, the grown film can be peeled off from the solution surface with tape so that a lightweight BiOI/In 2 O 3 /tape assembly can be easily constructed. Due to its low density and the BiOI/In 2 O 3 heterojunction formed, the resulting BiOI/In 2 O 3 /tape assembly exhibits superior photocatalytic activity per gram towards NO removal. Furthermore, the capillary force driven film pick-up process also induces a tight contact between the film and the tape, which makes the assembly highly twistable: its structural integrity and photocatalytic activity are largely preserved after 10,000 twists. Utilizing the film’s flexibility and twistability, we assemble a temperature-, auto-folding/unfolding photocatalyst system by transferring the film onto a memory-alloy-based structure, which mimics the movement of leaves in response to external stimulations and makes the gas–liquid interface-derived BiOI/In 2 O 3 /tape assembly suitable for use in space- and weight-limited environments.