Few-Layered WS₂ Anchored on Co, N-Doped Carbon Hollow Polyhedron for Oxygen Evolution and Hydrogen Evolution

Abstract

Tungsten disulfide (WS2) is well known to have great potential as an electrocatalyst, but the practical application is hampered by its intrinsic inert plane and semiconductor properties. In this work, owing to a Co-based zeolite imidazole framework (ZIF-67) that effectively inhibited WS2 growth, few-layered WS2 was confined to the surface of Co, N-doped carbon polyhedron (WS2@Co9S8), with more marginal active sites and higher conductivity, which promoted efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). For the first time, WS2@Co9S8 was prepared by mixing in one pot of a liquid phase and calcination, and WS2 realized uniform distribution on the polyhedron surface by electrostatic adsorption in the liquid phase. The obtained hybrid catalyst exhibited excellent OER and HER catalytic activity, and the OER potential was only 15 mV at 10 mA cm–2 higher than that of noble metal oxide (RuO2). The improvement of catalytic activity can be attributed to the enhanced exposure of sulfur edge sites by WS2, the unique synergistic effect between WS2 and Co9S8 on the metal–organic framework (MOF) surface, and the effective shortening of the diffusion path by the hollow multi-channel structure. Therefore, the robust catalyst (WS2@Co9S8) prepared by a simple and efficient synthesis method in this work will serve as a highly promising bifunctional catalyst for OER and HER.

Dual CoxSy-Modified Tungsten Disulfide Double-Heterojunction Electrocatalyst for Efficient Hydrogen Evolution in All-pH Media

“…To our delight, WS 2 /Co 9 S 8 /Co 4 S 3 with low loading mass is suitable for all-pH conditions and has much higher catalytic activity in alkaline media, such as the overpotentials of WS 2 /W 2 C@ NSPC (205 mV) and graphene/WS 2 (243 mV) are higher. More importantly, in contrast to the single heterojunction (WS 2 /Co 9 S 8 ) that both WS 2 and Co 9 S 8 decorate on the Co/ NC surface (271 mV), 59 it is very obvious that the overpotential of WS 2 /Co 9 S 8 /Co 4 S 3 decreases by nearly 100 mV to reach 10 mA cm −2 in 1 M KOH. Therefore, it can be concluded that the double heterojunctions (WS 2 /Co 9 S 8 and WS 2 /Co 4 S 3 ) have better HER activity than the single heterojunction (WS 2 /Co 9 S 8 ) or bare Co 9 S 8 /Co 4 S 3 due to the introduction of WS 2 /Co 4 S 3 heterojunctions.…”

2D iron/cobalt metal–organic frameworks with an extended ligand for efficient oxygen evolution reaction

“…Secondly, the energy density of hydrogen is extremely high, which is about 120 MJ kg −1 . [7][8][9] Hydrogen can be obtained from a variety of sources, 10,11 and water splitting is considered as a promising means and includes the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). 12,13 The OER involves a four-electron process, and its sluggish kinetics leads to inefficient energy conversion and thus severely limits the application of water electrolytic devices.…”

Reactive template‐derived interfacial engineering of CoP/CoO heterostructured porous nanotubes towards superior electrocatalytic hydrogen evolution

“…On the other hand, nanoarchitectonics design also enables improvement of the accessibility and utilization of active sites, reduction of the resistance of mass diffusion, and improvement of the electron‐transfer efficiency 44,45 . As a kinetically desirable open nanostructure, hollow and porous nanotubes are especially conducive to electrocatalysis due to the intriguing structure‐induced properties, including the abundant outer and inner accessible surface, available inside hollow space, low density, sufficient permeation of the electrolyte, and open voids for mass transportation and gas release, which distinctly differ from their solid counterparts and are synergistically beneficial to expedite the reaction kinetics 22,46,47 . Taking these considerations into account, it can be envisioned that the crafting of TMP/metal oxide heterojunction nanotubes would be a promising strategy to deliver superior HER performance by the synergistic utilization of the electronic regulation effect and architectural advantages.…”