Synthesis of double-helical snip nanowires for visible-light-driven photocatalytic degradation of dyes

As the first carbon-free double helical semiconductor at an atomic scale, tin phosphide iodide (SnIP) has garnered growing interest due to its high structural flexibility, band gap in the visible spectrum range, and non-toxicity. Herein, we report the chemical vapor transport synthesis of SnIP nanowires (NWs). The photocatalytic activity of SnIP NWs was evaluated through the degradation of two representative toxic dyes, methylene blue (MB) and malachite green (MG), under visible light irradiation (lambda > 400 nm). These NWs exhibited notable photocatalytic efficiency, achieving degradation rates over 97% for MB and 95% for MG within 100 min of visible light exposure. The degradation data align well with a pseudo-first-order reaction kinetics model for both dyes, with rate constants of 0.0347 and 0.0295 min-1. Furthermore, the synthesized catalyst demonstrated exceptional stability and recyclability, maintaining its efficient performance till six duplicate operations cycles. Scavenger testing indicated that holes and OH radicals were the main active species driving the dye's photodegradation. The unusual photocatalytic efficiency can be attributed to their favorable band gap within the visible spectrum range and unique one-dimensional structure. The results demonstrate that the SnIP NWs offer a promising choice for eco-friendly dye photodegradation.