Solar light-responsive Ag/CdS/TNTs (TiO2 nanotubes) photocatalysts for enhanced CO2 photoreduction and hydrogen evolution

Abstract

The prepared ternary Ag/CdS/TNTs S-scheme heterojunction has superior morphology and enhanced photocatalytic performance. Under solar light, the yield of photocatalytic CO 2 to CO by Ag/CdS/TNTs nanocomposites was 1455.6 μmol‧g -1 ‧h -1 and the H 2 evolution rate by the nanocomposites was 3700.57 μmol‧g -1 ‧h -1 , which were much better than pure materials. • The in situ one-time synthesis of Ag/CdS/TNTs (TiO 2 nanotubes) S-scheme heterojunction with the help of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) was simple and convenient. • The yield of photocatalytic CO 2 to CO by Ag/CdS/TNTs nanocomposites was 1455.6 μmol‧g -1 ‧h -1 , which was 1.5 times by pure CdS NPs. • It was found that Ag/CdS/TNTs nanocomposites displayed the H 2 evolution rate of 3700.57 μmol‧g -1 ‧h -1 , which was twice pure TiO 2 NPs. Solar-to-chemical energy conversion via heterogeneous photocatalysis is one of the effective approaches to tackle the growing environmental and energy challenges. Homogeneously dispersed silver nanoparticles (Ag NPs) and cadmium sulfide nanoparticles (CdS NPs) with average particle size not more than 20 nm were fabricated on the surface of titanium dioxide nanotubes (TNTs) (Ag/CdS/TNTs) with the help of sodium dodecyl benzene sulfonate (SDBS). Herein, more surface active sites are created on the surface of nanocomposites. The experimental results demonstrate that the photocurrent intensity of the nanocomposites obviously increased, which effectively improves the photocatalytic activity. The results of photocatalytic experiments indicated that using triethanolamine (TEOA) and acetonitrile (MeCN) as sacrificial agents, the nanocomposites afford the CO yield from CO 2 (1455.6 μmol‧g −1 ‧h −1 ). Besides, Ag/CdS/TNTs nanocomposites displayed the H 2 evolution rate of 3700.57 μmol‧g -1 ‧h -1 , which was twice as much as pure TiO 2 NPs. The increase in the photocatalytic ability of the nanocomposites is basically attributed to the three materials formation S-scheme heterojunction which reduce the recombination probability of the photo-induced electrons and holes and thus enhances the photocatalytic activitys. Ultimately, a photocatalytic reaction mechanism is proposed for Ag/CdS/TNTs nanocomposites in the reduction of CO 2 .