Plasma-modified Ti3C2Tx/CdS hybrids with oxygen-containing groups for high-efficiency photocatalytic hydrogen production.

Noble-metal-free Ti3C2Tx/CdS hybrids with oxygen-containing groups were successfully prepared through a mild solvothermal method of in situ heterogeneous nucleation. The abundant oxygen-containing groups and the increased surface roughness of plasma-treated Ti3C2Tx sheets provided active sites for the heterogeneous nucleation of CdS nanoparticles and strengthened the physical bond between CdS NPs and layered Ti3C2Tx. The optimized Ti3C2Tx/CdS hybrid without noble-metal co-catalyst achieved a high hydrogen-production rate of 825 μmol h-1 g-1 with an apparent quantum efficiency of 10.2% at 450 nm. The prepared Ti3C2Tx/CdS hybrid with 1.0 wt% Ti3C2Tx had a photocatalytic hydrogen-production rate higher than those of pure CdS nanoparticles and the Ti3C2/CdS hybrid obtained using non-plasma-treated Ti3C2 as the support matrix under visible-light irradiation. The photocatalytic-activity improvement of CdS nanoparticles was due to the increased hydrophilicity after plasma treatment with the abundant oxygen-containing groups on the Ti3C2Tx surface and the intimate contact between CdS nanoparticles and layered Ti3C2Tx. The former enabled the effective capture of water molecules and hydrogen ions by oxygen-containing groups on the surface of plasma-treated Ti3C2Tx. The latter provided a stable transfer channel for electrons to suppress the recombination of photogenerated electron-hole pairs. The proposed schematic for the improved photocatalytic activity of CdS nanoparticles decorated with plasma treated Ti3C2Tx was further confirmed by transient photocurrent response and time-resolved photoluminescence analyses.