Coupled porosity and heterojunction engineering: MOF-derived porous Co₃O₄ embedded on TiO₂ 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 Co₃O₄ was embedded onto n-type vertical TiO₂ nanotube via an in-situ thermal etching method. ZIF-67 was employed as the structural template for Co₃O₄, which then augmented the light harvesting ability of the resultant photocatalyst. Such improvement was prompted by the light reflecting and directing attributes of porous Co₃O₄. 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.