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

Abstract

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 cost-effective 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 μmol·g⁻¹·h⁻¹), while the CH₄ selectivity over CoOOH/BiOBr reached 72.59 % (20.06 μmol·g⁻¹·h⁻¹). The outstanding photocatalytic 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.