Built-in electric field mediated S-scheme charge migration and Co-N4(II) sites in cobalt phthalocyanine/MIL-68(In)-NH2 heterojunction for boosting photocatalytic nitric oxide oxidation.

The novel Molecular Cobalt Phthalocyanine modified MIL-68(In)-NH 2 S-scheme Heterojunction exhibit excellent NO oxidation performance with low toxic NO 2 generation. The enhanced activity can be attributed to the Strong O 2 Activation and Enhanced Built-in electric fields [Display omitted] • Molecular-dispersed CoPc/MIL-68(In)–NH 2 heterojunction with Co-N4(II) sites has been successfully synthesized. • The enhanced built-in electric field promote an efficient S-scheme charge transfer. • The Co-N4(II) sites displays bifunctional effects for capturing photoexcited electrons and promoting the O 2 activation. • Improved NO oxidation efficiency and suppression of toxic by-products are achieved. The efficiency of photocatalytic Nitric Oxide(NO) oxidation is limited by the lack of oxygen(O 2) active sites and poor charge carrier separation. To address this challenge, we developed a molecular Cobalt Phthalocyanine modified MIL-68(In)–NH 2 photocatalyst with a robust Built-in electric field(BIEF). In the 2 % CoPc-MIN sample, the BIEF strength is increased by 3.54 times and 5.83 times compared to pristine CoPc and MIL-68(In)–NH 2 , respectively. This BIEF facilitates the efficient S-scheme charge transfer, thereby enhancing photogenerated carrier separation. Additionally, the Co-N4(II) sites in CoPc can effectively trap the separated photoexcited electrons in the S-scheme system. In addition, the Co-N4(II) sites can also serve as active sites for O 2 adsorption and activation, promoting the generation of superoxide radical (O 2 –), thereby driving the direct conversion of NO to nitrate(NO 3 –). Consequently, the 2 % CoPc-MIN sample exhibits a remarkable photocatalytic NO removal efficiency of 79.37 % while effectively suppressing the formation of harmful by-product nitrogen dioxide(NO 2) to below 3.5 ppb. This study provides a feasible strategy for designing high-efficiency O 2 activation photocatalysts for NO oxidation. [ABSTRACT FROM AUTHOR]