Simultaneous CO2 and NO Conversion by Spatially Locating Dual Photocatalytic Sites on a Microporous Polymer.

Direct photocatalytic recycling of CO2 from practical exhaust gas is highly desirable but challenged by the competitive O2 reduction and coexisting NO pollutant. O2 as an inevitable component seriously suppresses CO2 reduction while being essential for photocatalytic NO removal. Herein, we introduce a SiO2-templated porphyrin-based polymer (STP) for integrating Pd(II) sites toward selective CO2 reduction and assembling TiO2 nanoparticles as NO oxidation sites. The TiO2-mediated electron transfer process facilitates the charge separation at the spatially separated Pd(II) and TiO2 sites. The O2 effect can be balanced between CO2 reduction and NO oxidation to achieve remarkable efficiency for CO2 reduction (2.8 mmol g-1 h-1) and NO removal (50.6%) in simulated flue gas under visible-light irradiation. In contrast, CO2 reduction is almost completely inhibited on Pd/TiO2 without the STP layer. Further, the reaction mechanism reveals the parallel pathways of selective CO2 reduction and NO oxidation on the designed TiO2/Pd-STP composite. This study demonstrates a feasible strategy for building dual active sites into CO2-affinitive polymers capable of simultaneous carbon recycling and pollution abatement in practical environments.