Ti₃C₂ Quantum Dots Modified 3D/2D TiO₂/g-C₃N₄ S-Scheme Heterostructures for Highly Efficient Photocatalytic Hydrogen Evolution

Abstract

Photocatalytic hydrogen production is a promising technology to alleviate the problems of energy shortage and environmental pollution faced by human society. In this paper, the S-scheme heterojunction TiO 2 /g-C 3 N 4 was modified by Ti 3 C 2 quantum dots (QDs) to prepare a three-dimensional/two-dimensional/zero-dimensional (3D/2D/0D) photocatalyst for photocatalytic hydrogen production. The S-scheme heterojunction structure reduces the recombination rate of photogenerated electron−hole pairs and produces more photogenerated electrons. At the same time, Ti 3 C 2 quantum dots as electron acceptors improve the ability to capture transition electrons, obtain more photogenerated carriers involved in surface reactions, and increase the number of active sites. The TiO 2 /g-C 3 N 4 /Ti 3 C 2 QDs composite catalyst shows excellent photocatalytic hydrogen evolution performance under visible light due to its unique structure and optical properties. The photocatalytic hydrogen production rate reached the maxima of 5540.21 μmol•h −1 g −1 , which is nearly 2 times higher than the production rates observed for TiO 2 /g-C 3 N 4 . The structure of 3D/2D/0D TiO 2 /g-C 3 N 4 /Ti 3 C 2 QDs was constructed, and the electron transfer path was verified by transient absorption spectroscopy and density functional theory calculation. KEYWORDS: TiO 2 /g-C 3 N 4 composites, Ti 3 C 2 quantum dots, S-scheme heterojunction, photocatalytic hydrogen production, DFT calculation

Femtosecond transient absorption spectroscopy investigation into the electron transfer mechanism in photocatalysis

“…103 For cocatalyst-modified S -scheme HPs, Dong et al revealed the electron dynamics of Ti 3 C 2 quantum dot (QD)-modified TiO 2 /g-C 3 N 4 S -scheme HPs by fs-TAS. 104 The fs-TAS results indicate that the photogenerated electrons in the CB of g-C 3 N 4 will further transfer to Ti 3 C 2 QDs. In conclusion, the dynamics of photogenerated carriers are more complicated in multicomponent HPs, so it is necessary to investigate them more intensively via the fs-TAS technique.…”

Manipulation of Charge-Transfer Kinetics via Ti3C2Tx (T = −O) Quantum Dot and N-Doped Carbon Dot Coloading on CdS for Photocatalytic Hydrogen Production

“…Obvious electron transfer at the CdS/MQDs and CdS/NCDs interfaces can be observed in Figure 7d and Figure 7e, respectively. 79,80 The consequential schematic of charge transfer (inset of Figure 7d,e) reveals that the CdS to MQDs electron transfer would happen upon hybridization, while at the CdS/NCDs interface, the elelctron would transfer from NCDs to CdS. This means that the hole will be transfer from CdS to NCDs.…”

An efficient photocatalytic system composed of Ti3C2 quantum dots incorporated in TiO2 nanosheets and CuWO4 nanoparticles: fabrication and its photocatalytic activity for H2 production

“…The photocatalytic activity of the TiO 2 -based photocatalyst is obviously enhanced when using MXene quantum dots. 35 It is well known that Ti 3 C 2 T x can be oxidized to TiO 2 in air. It was reported that a highly efficient photocatalyst consisting of Ti 3 C 2 T x and TiO 2 could be prepared by partial oxidation of the Ti 3 C 2 T x .…”