Activation of 2D cobalt hydroxide with 0D cobalt oxide decoration for microplastics degradation and hydrogen evolution

The 2D semiconductors are important players in environmental and energy fields due to their unique catalytic and physical properties defined by their dimensionality. Versatile functionalities on one 2D matrix will enlarge its application scopes but require dedicated engineering paths. In this work, we present a cross-dimensional strategy by decorating 0D Co3O4 onto 2D Co(OH)2 to form a multifunctional photocatalyst. The one-pot hydrothermally synthesized Co3O4@Co(OH)2 composite is capable of degrading polystyrene microplastics with an efficiency of 40% under 0.495 W white LED illumination. In a separated experiment, H2 evolution reaction from water splitting was evaluated in absence of sacrificial agents leading to 43 & mu;mol g-1 and to an apparent quantum efficiency of 3.48% at 420 nm. The study of the energy band diagrams by UV-Visible and ambient photoemission spectroscopy and the analysis of the radicals involved in the reaction of photocatalytic degradation allow to unveil the mechanisms for both the processes herein studied. Finally, we could confirm that the heterostructure benefits the redox potentials of 2D and 0D counterparts and facile electron transfers when crossing two different dimensions. These results provide guidelines and inspiration for cross-dimensional activations of lowdimensional materials for versatile functionalities.

Automated summary

In this study, a multifunctional photocatalyst was formed by decorating 0D Co3O4 onto 2D Co(OH)2. The synthesized Co3O4@Co(OH)2 composite showed an efficiency of 40% in degrading polystyrene microplastics under 0.495 W white LED illumination, and achieved a H2 evolution reaction of 43 μmol g-1 without sacrificial agents. The energy band diagrams and analysis of radicals involved in the photocatalytic degradation revealed the mechanisms of both processes.