Plasmon-induced catalytic CO2 hydrogenation by a nano-sheet Pt/HxMoO3-y hybrid with abundant surface oxygen vacancies

Taking full advantage of solar light to promote CO2 hydrogenation remains a challenge in the catalysis field. Combining a degeneratively-doped metal oxide and a precious metal to obtain hybrids with plasmonic absorption in the visible-light region enables the high-efficiency utilization of solar light in photothermal catalysis. Herein, MoO3 samples with different morphologies were synthesized and combined with Pt to form hybrid materials with a strong plasmonic effect. Among the Pt/MoO3 hybrids with various morphologies, the Pt/HxMoO3-y(Sheet) hybrid displayed the best performance in the photothermal synergistic catalysis of the reverse water-gas shift (RWGS) reaction at 140 degrees C under visible light irradiation because of the advantages of its nanosheet structure (e.g., a high specific surface area, high proportion of exposed surface atoms, and good optical transparency). The Pt/HxMoO3-y(Sheet) catalyst outperformed Pt/HxMoO3-y hybrids with a bulk, belt, or rod morphology. Thermogravimetry, UV-vis-NIR diffuse reflectance spectroscopy, and model reactions demonstrated that the Pt/HxMoO3-y(Sheet) hybrid contained the largest amount of surface O vacancies and exhibited the strongest plasmonic absorption, which are the primary reasons for its highest catalytic activity among the investigated hybrid catalysts. Photoelectric characterization revealed that the Pt/HxMoO3-y(Sheet) hybrid could generate hot electrons under visible-light irradiation. X-ray photoelectron spectroscopy measurements showed a reversible redox event of the Mo atoms, demonstrating that the O vacancies in Pt/HxMoO3-y(Sheet) acted as active sites and regenerated during the reaction. A possible mechanism is proposed for the photothermal synergistic catalysis in the RWGS reaction. The nanosheet-structured Pt/HxMoO3-y hybrid can exploit solar energy to greatly reduce energy consumption during the CO2 hydrogenation reaction, providing a greener and energy-saving scheme for the conversion of CO2 to CO.

Automated summary

Utilizing degeneratively-doped metal oxide and precious metal hybrids with plasmonic absorption in the visible-light region allows for efficient utilization of solar light in photothermal catalysis. Among various morphologies of Pt/MoO3 hybrids, the nanosheet-structured Pt/HxMoO3-y(Sheet) catalyst demonstrated the best performance in the photothermal synergistic catalysis of the RWGS reaction, attributed to its high specific surface area, proportion of exposed surface atoms, and optical transparency. Additionally, the Pt/HxMoO3-y(Sheet) hybrid contained the largest amount of surface O vacancies and exhibited the strongest plasmonic absorption, leading to its highest catalytic activity among the investigated hybrid catalysts.