Mo₂C-MXene/CdS Heterostructures as Visible-Light Photocatalysts with an Ultrahigh Hydrogen Production Rate

Abstract

Here, we report a visible-light photocatalyst (Mo 2 C-MXene/CdS) with H 2 production rate higher than that of state-ofthe-art catalysts based on noble metals or other MXenes. The photocatalyst was constructed from Mo 2 C MXene, Cd(NO 3 ) 2 • 4H 2 O, and thiourea with ethylenediamine, which has an acanthosphere structure with Mo 2 C two-dimensional (2D) sheets covered by wurtzite CdS nanocrystals. From theoretical calculation, Mo sites in the Mo 2 C-MXene/CdS(110) heterostructure provide an efficient reaction site for the hydrogen evolution reaction (ΔG H* = −0.18 eV). The electronic structures demonstrate that this heterostructure has favorable band gap and band edge position for water splitting. In experimental measurements, the photocatalyst shows a H 2 production rate of 17 964 μmol g −1 h −1 . The H 2 production is ca. 20% higher than the previously reported value of Ti 3 C 2 MXene catalysts and ca. 11% higher than that of noble-metal catalysts. Therefore, Mo 2 C-MXene/CdS heterostructure is a promising catalyst with ultrahigh performance to replace noble-metal catalysts.

Construction and performance of CdS/MoO2@Mo2C-MXene photocatalyst for H2 production

“…The number of formed heterostructures between CdS and MoO 2 @Mo 2 C-MXene increases with the loading of MoO 2 @Mo 2 C-MXene, which is beneficial to the enhancement of photocatalytic activity. In particular, the optimal sample of CMM5 exhibits the best H 2 production rate of 22,672 μmol/(g•h), which is ~21% higher than that of CdS/Mo 2 C [43]. The reduction of photocatalytic activity with the further increase of MoO 2 @Mo 2 C-MXene is probably because excessive MoO 2 @Mo 2 C-MXene can cover the active sites of the catalysts [28,56].…”

“…Mo 2 C MXene is another MXene prepared by etching Mo 2 Ga 2 C [38][39][40][41][42]. In the previous work [43], we found that Mo 2 C-MXene/CdS heterostructure exhibited an ultra-high H 2 production rate of 17,964 μmol/(g•h).…”

Recent Research Progress in the Structure, Fabrication, and Application of MXene-Based Heterostructures

“…The M@T/CIS photocatalyst exhibited a high H 2 evolution rate of 356.27 μmol·g −1 ·h −1 , which was about 69.5 and 636.2 times higher than that of the Ti 3 C 2 MXene@TiO 2 (M@T) and CIS sample, respectively. Jin et al [ 119 ] constructed Mo 2 C-MXene/CdS heterostructures as photocatalysts by the hydrothermal method. The experiment of photocatalytic hydrogen production showed that the photocatalyst showed excellent hydrogen production performance compared with the previously reported Ti 3 C 2 MXene catalyst.…”

Metal (Mo, W, Ti) Carbide Catalysts: Synthesis and Application as Alternative Catalysts for Dry Reforming of Hydrocarbons—A Review

“…When using an in situ HF-formed etchant, intercalation proceeds at the etching step due to the presence of Li + , NH 4 + , or K + ions. In the case of the basic intercalant, the MXene phase is further washed to obtain a pH below 8 [171,182,183].…”

“…Recently, an increasing number of research reports on modified metal carbides from the MXene group to improve catalytic [169,180], conducting [186,187], photocatalytic [167,182], and optical response properties [167,182] have been published. He et al [187] synthesized Ni 1.5 Co 1.5 S 4 @Ti 3 C 2 nanocomposites for high-performance supercapacitors.…”