Co species modulating of BiOBr-based Z-scheme heterojunction for the transform photoreduction CO2 products from CO to CH4

The utilization of solar energy in photocatalytic CO2 reduction technology has demonstrated a significant potential in addressing the challenges of environmental pollution and energy shortage issues. Precise modulating of the photoreduction CO2 pathway to achieve desired products is of particular interest, while the design of costeffective and robust catalysts remains crucial. Herein, a series of BiOBr-based photocatalysts with different Co species were synthesized through a facile simple hydrothermal method in combination with the mechanical mixing. The Co species, which can be precisely modulated from Co3O4 to CoOOH by adjusting the concentration of H2O2, were anchored into the BiOBr nanospheres to establish rich Z-scheme heterojunction interfaces. The Co species modulating of BiOBr-based Z-scheme heterojunction can achieve the transform photoreduction CO2 products from CO to CH4. The CO selectivity in CO2 photoreduction to reached 98.10 % (54.10 mu mol center dot g- 1 center dot h- 1), while the CH4 selectivity over CoOOH/BiOBr reached 72.59 % (20.06 mu mol center dot g- 1 center dot h- 1). The outstanding photo- catalytic performance and selective regulation of products are ascribed to the modulation of Co species in the BiOBr-based heterojunctions, which enables the customization of the photoreduction CO2 pathway to achieve the desired products transformation from CO to CH4. In situ experiments and theoretical calculations reveal that the excellent CO selectivity observed in Co3O4/BiOBr heterojunction can be ascribed to a lower energy for *CO species compared with that of hydrogenation to *HCOOH and *CHO intermediates. Conversely, the presence of *HCOOH and *CHO intermediates with lower energy levels compared with *CO species achieved superior CH4 selectivity in CoOOH/BiOBr heterojunction. This precise design strategy insights into the meticulous customization of Co species in semiconductor-based heterostructures at the molecular level, and enlightens the selective regulation of desired products for catalysis applications.