Coupled porosity and heterojunction engineering: MOF-derived porous CoO embedded on TiO nanotube arrays for water remediation.

Strive to develop the interaction and efficient co-catalysts is one of the vital projects in realizing hybrid photocatalytic systems for water remediation. In this work, p-type porous CoO was embedded onto n-type vertical TiO nanotube via an in-situ thermal etching method. ZIF-67 was employed as the structural template for CoO, which then augmented the light harvesting ability of the resultant photocatalyst. Such improvement was prompted by the light reflecting and directing attributes of porous CoO. Therefore, a remarkable MB removal rate was attained under sunlight irradiation, with superoxide radical being identified as the major reactive species. Photoelectric properties evaluation also verified that the p-n heterojunction developed herein exhibits outstanding charges separation ability with low impedance, particularly under light irradiation. This work highlights the idea on coupling both porous and p-n heterojunction engineering in augmenting photoactivity of catalyst, while offering insights in such structure-mediating approach.