Triphase Photocatalytic CO₂ Reduction over Silver‐Decorated Titanium Oxide at a Gas–Water Boundary

Abstract

Photocatalytic CO2 reduction reaction (CO2RR) is an attractive process to convert CO2 into valuable chemicals. But this reaction is often restricted by the poor mass transfer of CO2 in the liquid phase. Here, we have developed a triphase photocatalytic CO2RR system by supporting Ag‐decorated TiO2 nanoparticles at a gas–water boundary with hydrophobic–hydrophilic abrupt interfacial wettability. Such a triphase system allows the rapid delivery of gas‐phase CO2 to the surface of photocatalysts while maintaining an efficient water supply and uncovered active sites. Ag‐TiO2 supported at the gas–water boundary showed a CO2 reduction rate of 305.7 μmol g−1 h−1, without hole scavengers, approximately 8 times higher than the nanoparticles dispersed in the liquid phase. Even using diluted CO2 (10 %) as the reactant, the CO2RR activity was superior to most reported Ag‐TiO2 based photocatalysts using pure CO2. The findings provide a general strategy to promote the interfacial CO2 mass transfer to improve photoactivity and selectivity.

Photocatalytic CO2reduction on Cu single atoms incorporated in ordered macroporous TiO2toward tunable products

“…The photocatalytic CO 2 reduction reaction in liquid-solid system is restricted by the low solubility of CO 2 in water (33 mM at 1 atm and 25 °C) and the poor mass transfer of CO 2 in the liquid phase. 79 However, the diffusion coefficient of CO 2 in the gas phase (∼0.1 cm 2 s −1 ) is about 10 000 times that in the liquid phase (∼1 × 10 −5 cm 2 s −1 ), which allows the rapid delivery of CO 2 molecules to the surface of photocatalysts with uncovered active sites. The adsorption and activation of CO 2 and H 2 O can be implemented more efficiently in the gas-solid system, and thus the photocatalyst shows higher activity.…”

Photocatalytic CO2conversion: from C1 products to multi-carbon oxygenates

“…(b) Schematic illustration of the photocatalytic CO 2 reduction system based on Ag-TiO 2 supported at the gas-water boundary. 97 Copyright 2022, Wiley-VCH. (c) The mechanism of three-phase photocatalysis for boosting mass transfer.…”

“…7b). 97 The gas-liquid-solid three-phase interface promoted the transfer of gas-phase CO 2 to the surface of photocatalyst, while maintaining high-efficiency water supply and uncovered active sites. Even without hole scavengers, the CO 2 photoreduction rate was approximately 8 times higher than the nanoparticles dispersed in the liquid phase, providing a strategy for boosting the interfacial CO 2 mass transfer.…”

Robust route to photocatalytic nitrogen fixation mediated by capitalizing on defect-tailored InVO4 nanosheets

“…4 Among the myriad reports to duplicate the work of nitrogenase, as an energy-saving and environmentally-friendly strategy, photocatalytic nitrogen fixation using solar light provides new opportunities for NH 3 synthesis. [5][6][7] Nevertheless, the cleavage energy of the nitrogen-nitrogen triple bond in the nitrogen molecule is as high as 941 kJ mol −1 , which makes the activation of nitrogen extremely difficult. 8,9 Clearly, it is highly desirable to design efficient photocatalysts to address the aforementioned problems.…”