Photocatalytic water oxidation with iron oxide hydroxide (rust) nanoparticles

Hematite has attracted considerable interest as a photoanode material for water oxidation under visible illumination. Here, we explore the limits of photocatalytic water oxidation activity with iron (III) oxide hydroxide nanocrystals and NaIO 4 as a sacrificial electron acceptor ( E = 1.63 V NHE at pH = 0.5 ). The sol was prepared by hydrolysis of FeCl 3 in boiling 0.002-M HCl solution and confirmed to mainly consist of s - FeO ( OH ) (akaganeite) particles with 5 to 15 nm diameter. From a 0.01 M aqueous NaIO 4 solution, the sol evolves between 4.5 and 35.2 μ mol O 2 h − 1 , depending on pH, light intensity ( > 400 nm , 290 to 700 mW cm