Manipulating Coordination Structures of Mixed-Valence Copper Single Atoms on 1T-MoS₂ for Efficient Hydrogen Evolution

Abstract

Directing single atoms (SAs) to occupy specific lattice sites in support materials and correlating the resulting changes in atomic coordination structures to catalytic activity are crucial for the rational design of high-performance single-atom catalysts (SACs). Herein, for the same copper (Cu) SAs, two coordination structures on 1T-phase molybdenum disulfide (MoS2) are identified. In the adsorption model, Cu SAs are coordinated onto the outermost sulfur (S) plane in a trigonal pyramidal geometry (Cuads@MoS2), while in the substitution model, Cu SAs are substituted with molybdenum (Mo) atoms (Cusub@MoS2), octahedrally coordinating with six S atoms in 1T-MoS2. Interestingly, in both coordination models, Cu­(I) and Cu­(II) SAs simultaneously exist. Cuads@MoS2 (173 mV) and Cusub@MoS2 (160 mV) demonstrate significantly reduced overpotential (at 10 mA cm–2) for the hydrogen evolution reaction (HER) compared to that of 1T-MoS2 (235 mV) under acidic condition (0.5 M H2SO4). Additionally, theoretical results reveal that different coordination structures would result in distinct active sites, where in Cuads@MoS2, the Cu SAs are the active sites, whereas in Cusub@MoS2, the S atoms most adjacent to the Cu SAs are the major active sites. Accurately determining the atomic coordination structures of SAs and uncovering their structure–property relationships are essential to guiding future geometry and structural research on SACs.

Detecting and Quantifying Wavelength‐Dependent Electrons Transfer in Heterostructure Catalyst via In Situ Irradiation XPS

“…As expected, the Tafel slope of CS‐2 (201 mV dec −1 ) was smaller than SnO 2 (229 mV dec −1 ) and g‐C 3 N 4 (211 mV dec −1 ), revealing that the sluggish hydrogen evolution kinetics had been significantly accelerated after the heterojunction formed (Figure S14c , Supporting Information). [ 52 , 53 , 54 ] The photoelectrochemical performances of other composite samples were also compared to illustrate the effect of g‐C 3 N 4 content. The CS‐2 showed the highest current density among three composites.…”

Zinc Single Atom Confinement Effects on Catalysis in 1T-Phase Molybdenum Disulfide

“… 37 Li et al reported the ability to enhance the HER performance of 1T-MoS 2 by either substituting lattice sites with copper (Cu) SAs or adsorbing Cu SAs along the 1T-MoS 2 basal plane. 38 Each of these methods of stabilizing Cu SAs was achieved by employing syringe injection and hydrothermal synthetic methods, respectively. Meanwhile, in a volcano plot reported by Deng et al, Zn demonstrated a Δ G H* value near 0 eV, indicating that it is one of the few nonprecious metals that may be able to modify the HER activity of MoS 2 .…”

“…Huang et al discovered that hydrothermally synthesizing 1T-MoS 2 with Fe, Co, and Ni enhances HER activity in alkaline media by doping the guest metals into the 1T-MoS 2 lattice in a 1:6 X:Mo ratio (X = Fe, Co, or Ni) . Li et al reported the ability to enhance the HER performance of 1T-MoS 2 by either substituting lattice sites with copper (Cu) SAs or adsorbing Cu SAs along the 1T-MoS 2 basal plane . Each of these methods of stabilizing Cu SAs was achieved by employing syringe injection and hydrothermal synthetic methods, respectively.…”

Directly Grow Ultrasmall Co2P QDs on MoS2 Nanosheets to Form Heterojunctions Greatly Boosting Electron Transfer toward Hydrogen Evolution

“…However, since the catalytically active sites of MoS 2 are usually located in a few edge positions, resulting in catalytic inertness at most of the exposed sites, which also leads to its low catalytic activity. 15 Besides, severe aggregation and unsatisfactory electrical conductivity further hinder the enhancement of HER activity. 16 Therefore, there is an urgent need to find out how the activity of the base surface can avoid aggregation and enhance conductivity.…”

“…(2) Many 2D materials themselves are good electrocatalysts for HER, such as molybdenum disulfide (MoS 2 ). However, since the catalytically active sites of MoS 2 are usually located in a few edge positions, resulting in catalytic inertness at most of the exposed sites, which also leads to its low catalytic activity . Besides, severe aggregation and unsatisfactory electrical conductivity further hinder the enhancement of HER activity .…”