Hydrogenation is an effective approach to improve the performance of photocatalysts within
defect engineering methods. The mechanism of hydrogenation and synergetic effects
between hydrogen atoms and local electronic structures, however, remain unclear due to the
limits of available photocatalytic systems and technical barriers to observation and measurement.
Here, we utilize oxygen vacancies as residential sites to host hydrogen atoms in a
layered bismuth oxychloride material containing defects. It is confirmed theoretically and
experimentally that the hydrogen atoms interact with the vacancies and surrounding atoms,
which promotes the separati30on and transfer processes of photo-generated carriers via the
resulting band structure. The efficiency of catalytic activity and selectivity of defective bismuth
oxychloride regarding nitric oxide oxidation has been improved. This work clearly
reveals the role of hydrogen atoms in defective crystalline materials and provides a promising
way to design catalytic materials with controllable defect engineering.