Facet-dependent photocatalytic NO conversion pathways predetermined by adsorption activation patterns.

Area of Science:

• Materials Science
• Environmental Chemistry
• Catalysis

Background:

• Different exposed facets of photocatalysts influence their properties and reactivity.
• The precise mechanisms behind facet-dependent photocatalytic reactions remain largely unelucidated.
• Understanding these mechanisms is crucial for designing efficient environmental remediation catalysts.

Purpose of the Study:

• To synthesize and compare bismuth oxycarbonate (Bi2O2CO3) with exposed {110} and {001} facets.
• To investigate the facet-dependent activation and reaction mechanisms in photocatalytic NO oxidation.
• To elucidate how different facets influence pollutant adsorption, activation, and product desorption.

Main Methods:

• Synthesis of flower-like Bi2O2CO3 with exposed {001} facets (001-BOC) and nanoflake Bi2O2CO3 with exposed {110} facets (110-BOC).
• Evaluation of photocatalytic activity for NO abatement using Electron Spin Resonance (ESR) spectra.
• Computational analysis using Density Functional Theory (DFT) and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS).

Main Results:

• 001-BOC demonstrated significantly higher photocatalytic activity for NO removal compared to 110-BOC.
• The superior performance of 001-BOC is attributed to enhanced activation of O2 and H2O, promoting reactive radical formation.
• Distinct adsorption-activation pathways were observed: 001-BOC facilitated NO to NO-/cis-N2O22- conversion, while 110-BOC led to NO+/N2O3 formation.

Conclusions:

• The {001} facet of Bi2O2CO3 enhances the oxidation of intermediates and promotes nitrate desorption, optimizing the NO oxidation pathway.
• Atomic arrangement differences on facets dictate distinct adsorption-activation patterns and conversion pathways.
• This study provides critical insights into facet-dependent reaction mechanisms, guiding the design of advanced photocatalysts for environmental applications.