Understanding the Role of Nanoscale Heterointerfaces in Core/Shell Structures for Water Splitting: Covalent Bonding Interaction Boosts the Activity of Binary Transition-Metal Sulfides

Abstract

The appropriate catalyst model with a precisely designed interface is highly desirable for revealing the real active site at the atomic level. Herein, we report a proof-of-concept strategy for creating an exposed and embedding interface model by constructing a unique Co9S8 core with a full WS2 shell (Co9S8/FWS2) and a half WS2 shell (Co9S8/HWS2) to uncover the synergistic effect of heterointerfaces on the catalytic performances. Tailoring the heteroepitaxial growth of WS2 shell, Co9S8/HWS2 with exposed Co–S–W interfaces leads to the exceptional electron density changes on edged-S atoms with large amounts of lone-pair electrons. Meanwhile, the unique Co9S8/HWS2 could accelerate the kinetic adsorption of hydrogen- and oxygen-containing intermediates. Such Co9S8/HWS2 electrocatalysts show extremely low overpotentials of 78 and 290 mV at a current density of 10 mA cm–2 for hydrogen evolution reaction (HER) and oxygen evolution reaction, respectively. Using Co9S8/HWS2 as both the cathode and anode, an alkali electrolyzer delivers a current density of 10 mA cm–2 at a quite low cell voltage of 1.60 V. The results of both operando Raman spectroscopy and electron spin resonance indicate the presence of S–S terminal and S–S bridging with unsaturated S atoms during the HER process. The present work reveals the synergistic effects of nanoscale interfaces on overall electrocatalytic water splitting.

High‐Entropy Metal Sulfide Nanoparticles Promise High‐Performance Oxygen Evolution Reaction

“…e) Comparison of the overpotentials and Tafel slopes among quinary (CrMnFeCoNi)S x , quaternary (MnFeCoNi) 9 S 8 , ternary (FeCoNi) 9 S 8 , binary (NiFe) 9 S 8 , and unary Mn 9 S 8 , Co 9 S 8 , Ni 9 S 8 , and Fe 9 S 8 . f) Comparison of the overpotentials and Tafel slopes of our work (overpotential of quinary (CrMnFeCoNi)S x at a current density of 100 mA cm −2 ) with M x S y reported in the literature [ 15,25,42–51 ] (overpotential of M x S y at a current density of 10 mA cm −2 ).…”

Electronic modulation and interface engineering of electrospun nanomaterials‐based electrocatalysts toward water splitting

“…By using such electrocatalysts as both cathode and anode, low‐cost water splitting electrolyzer can be realized, which avoids the usage of different equipment and processes for the different types of HER and OER electrocatalysts. Similarly, to enhance the overall water splitting performance, the electronic modulation and interface engineering of the electrocatalysts are also desirable 199‐213 …”

“…(J) LSV curves for the electrolyzer before and after the 10 h testing. Reproduced with permission: Copyright 2020, American Chemical Society 212 . HAADF‐STEM, high‐angle annular dark‐field scanning transmission electron microscopy; HER, hydrogen evolution reaction; HWS 2 , half WS 2 shell; LSV, linear sweep voltammetry; OER, oxygen evolution reaction; STEM‐EDX, scanning transmission electron microscopy‐energy dispersive X‐Ray…”

Versatile construction of a hierarchical porous electrode and its application in electrochemical hydrogen production: a mini review

“…also had been widely investigated as electrocatalysts for oxygen evolution via solid-vapor treatment, and the rational design of catalysts is also an important concern. [94][95][96] Hollow and conductive Fe-Co-P alloys as excellent OER electrocatalysts were developed by carbonization and phosphidation of the Fe-Co metal-organic complex (MOC). 97 The structure of the Fe-Co MOC consists of highly uniform nanospheres.…”