Infrared Light-Driven LaW(O,N)3 OER Photoelectrocatalysts from Chloride Flux-Grown La4W3O15 Templating Precursors

Lanthanum tungsten oxynitride, LaW(O,N)3, possesses a perovskite structure and an n-type semiconducting character and is a promising candidate for photocatalytic (PC) and photoelectrochemical (PEC) solar water decomposition into oxygen and hydrogen. To maximize PC and PEC performance, synthesis of LaW(O,N)3 with a high specific surface area and high crystallinity is essential. Herein, we report the fabrication of highly porous, crystalline LaW(O,N)3 crystal structures through thermal ammonolysis and acidification of NaCl and KCl flux-grown La-rich lanthanum tungstate (La4W3O15) crystals. The NaCl and KCl flux-grown La4W3O15 samples were polyhedral crystals with smooth surfaces and high particle-dispersivity (i.e., a low degree of particle aggregation) that were dependent upon solute concentration rather than flux choice. After thermal ammonlysis and acidification, these La4W3O15 crystals became highly porous LaW(O,N)3 crystal structures with relatively high specific surface areas (13.3–17.6 m2 g–1). The r...