Photocatalytic CO₂ conversion on highly ordered mesoporous materials: Comparisons of metal oxides and compound semiconductors

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>In this study, the ordered mesoporous metal oxides (TiO<SUB>2</SUB> and SnO<SUB>2</SUB>) and compound semiconductors (ZnS, ZnSe, CdS, and CdSe) are manufactured and they exhibit several micrometers (μm) of particle size, and high surface area of about 100m<SUP>2</SUP>g<SUP>−1</SUP>. Well-developed crystallinities are prepared <I>via</I> simple nano-replication method by using a 3-D bicontinuous cubic <I>Ia</I>3<I>d</I> meso-structured ordered mesoporous silica KIT-6 as a hard-template. The visible-light-driven photocatalytic CO<SUB>2</SUB> conversion into CH<SUB>4</SUB> is carried out in the presence of H<SUB>2</SUB>O over various mesoporous materials. Prepared mesoporous materials show different light absorption behaviors and photocatalytic activities for conversion of CO<SUB>2</SUB>. The mesoporous compound semiconductors show higher CO yield rates than the mesoporous metal oxides, while mesoporous metal oxides show higher CH<SUB>4</SUB> yield rates than the mesoporous compound semiconductors. Compared to the commercial TiO<SUB>2</SUB> material (P25, Degussa), the mesoporous metal oxides (TiO<SUB>2</SUB>, SnO<SUB>2</SUB>) show 9 to 10 times higher yields of CH<SUB>4</SUB> and 2 to 3 times higher yields of CO owing to their high surface area. Especially, the mesoporous ZnS shows the highest CH<SUB>4</SUB> yield rate (3.620μmolg<SUB>cat</SUB> <SUP>−1</SUP>h<SUP>−1</SUP>) and the mesoporous CdSe shows the highest CO yield rate (5.884μmolg<SUB>cat</SUB> <SUP>−1</SUP>h<SUP>−1</SUP>) out of all photocatalysts considered in the present study. Although mesoporous CdS and ZnSe have great visible light absorption properties, they show relatively low CH<SUB>4</SUB> yield rates.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly ordered mesoporous metal oxides and compound semiconductors are manufactured. </LI> <LI> The photocatalytic CO2 conversion experiments are carried out on various mesoporous materials. </LI> <LI> Mesoporous ZnS photocatalyst shows the highest CH4 yield rate. </LI> <LI> Mesoporous CdSe photocatalyst shows the highest CO yield rate. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Average yield rates of CH<SUB>4</SUB> and CO by using various photocatalysts.</P> <P>[DISPLAY OMISSION]</P>