Morphology-dependent photocatalytic performance of nanoporous anodized stainless-steel

Abstract

Nanostructures can be created three-dimensionally by anodization on a stainless-steel mesh or a flat plate (NSSM and NSSP, respectively). Photodegradation tests were completed to optimize anodization. A concentration of 5 v/v% of perchloric acid with conditions of 20 V for 15 min, 20 V for 13 min, and 40 V for 20 min were selected for the 200 mesh, 50 mesh, and stainless-steel plates, respectively. The photocatalytic degradation efficiency values of benzene for NSSP, NSSM50, and NSSM200 were 71.4%, 92.3%, and 98.7% (R2 = 0.96, 0.98, 0.99), respectively. Hydrogen peroxide was used as an oxidant to support photocatalysis. NSSM200 showed the highest overall degradation rate, as well as those per weight and per surface area (0.14 min−1, 0.13 min−1 g−1, 0.42 min−1 m−2, respectively). All substrates were more effective for photocatalytic degradation of benzene at pH 7 compared to pH 3 or 11. NSSM50 and NSSP were stable during the recycle test, but NSSM200 was not. The three-dimensional morphology of NSSM exhibited a higher specific surface area than the planar NSSM nanostructures. Moreover, the optimal condition for NSSM consumed 5–6 times less energy per unit area than did NSSP. Efficient treatment of organic contaminants with a small amount of energy is beneficial environmentally, and NSSM showed more effective results than other photocatalysts.