Engineering Double Sulfur-Vacancy in CoS_1.097@MoS₂ Core–Shell Heterojunctions for Hydrogen Evolution in a Wide pH Range

Abstract

Heterostructured nanomaterials have arisen as electrocatalysts with great potential for hydrogen evolution reaction (HER), considering their superiority in integrating different active components but are plagued by their insufficient active site density in a wide pH range. In this report, double sulfur-vacancy-decorated CoS 1.097 @MoS 2 core−shell heterojunctions are designed, which contain a primary structure of hollow CoS 1.097 nanocubes and a secondary structure of ultrathin MoS 2 nanosheets. Taking advantage of the core−shell type heterointerfaces and double sulfur-vacancy, the CoS 1.097 @MoS 2 catalyst exhibits pH-universal HER performance, achieving the overpotentials at 10 mA cm −2 of 190, 139, and 220 mV in 0.5 M H 2 SO 4 , 1.0 M KOH, and 1.0 M PBS, respectively. Systematic theoretical results show that the double sulfur-vacancy can endow the CoS 1.097 @MoS 2 core−shell heterojunctions with promoted electron/mass transfer and enhanced reactive kinetics, thus boosting HER performance. This work clearly demonstrates an indispensable role of double sulfur-vacancy in enhancing the electrocatalytic HER performance of core−shell type heterojunctions under a wide pH operating condition.

ReS2/CdIn2S4–SV Heterojunctions for Photocatalytic Hydrogen Production

“…Analysis of the 5RCIS-S V photocatalyst revealed binding energies situated at 412.3, 405.6, 452.6, 445.1, 162.8, 161.6, 44.1, and 41.7 eV, correlating with the valence states of Cd, In, S, and Re as +2, +3, −2, and +4, respectively. Commonly, a shift toward a lower binding energy signifies an increase in electron density (electrons being gained), whereas a shift toward a higher binding energy denotes a decrease in electron density (loss of electrons), aiding in the analysis of electron transfer dynamics among components in heterojunction composite materials. , This principle is substantiated by a noticeable shift of 0.6 eV toward lower binding energy for the Re 4f 7/2 and 4f 5/2 peaks following the formation of the 5RCIS-S V composite, accompanied by a significant shift toward higher binding energy for the Cd 3d and In 3d peaks, indicative of electron transfer from CIS-S V to ReS 2 . A pronounced discrepancy in the S 2p binding energies between CIS-S V (162.5 and 161.3 eV) and ReS 2 (164.5 and 163.1 eV) is observed, attributable to S atoms being situated in dissimilar chemical environments.…”