Heterostructures Composed of N‐Doped Carbon Nanotubes Encapsulating Cobalt and β‐Mo₂C Nanoparticles as Bifunctional Electrodes for Water Splitting

Abstract

Herein, we demonstrate the use of heterostructures comprised of Co/β‐Mo2C@N‐CNT hybrids for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline electrolyte. The Co can not only create a well‐defined heterointerface with β‐Mo2C but also overcomes the poor OER activity of β‐Mo2C, thus leading to enhanced electrocatalytic activity for HER and OER. DFT calculations further proved that cooperation between the N‐CNTs, Co, and β‐Mo2C results in lower energy barriers of intermediates and thus greatly enhances the HER and OER performance. This study not only provides a simple strategy for the construction of heterostructures with nonprecious metals, but also provides in‐depth insight into the HER and OER mechanism in alkaline solution.

N‐Doped Carbon Nanotubes Encapsulating Ni/MoN Heterostructures Grown on Carbon Cloth for Overall Water Splitting

“…Besides, the XPS spectra (Figure S15a) show that after stability test the valence state of Ni was not be changed both in anode and cathode sides. Interestingly, the Ni in Ni/MoN@NCNT/CC was not be oxidized and remained unchanged in the OER process, which could be ascribed to the protection of carbon layer, consistent with some reported OER electrocatalysts, such as Co@NCF, FeNi@NC and Co/β‐Mo 2 C@N‐CNTs, Ni/Mo 2 C‐PC . However, the MoN was not very stable and oxidized into Mo 6+ species in the anode side (Figure S15b), which can enhance OER performance of electrocatalysts .…”

“…More TEM images are shown in Figure S7, further confirming nanoparticles were encapsulated in NCNT. Besides, many literatures reported that nanoparticles were encapsulated in carbon nanotubes, which are also confirmed by TEM images. Figure and S7 present similar results with those TEM images, so it is convincing that nanoparticles were encapsulated in NCNT and not anchored to their surface.…”

“…The value of I D /I G for Ni/MoN@NCNT/CC (1.18) is larger than that for Ni@NCNT/CC (1.13), indicating that more structural defects or higher disorder exist in the NCNT of Ni/MoN@NCNT/CC than in that of Ni@NCNT/CC. This might be ascribed to the process of co‐doping with N, Ni and MoN and the absence of part C atoms in the crystal structure of the NCNT, which could be beneficial to exposing more active sites.…”

“…Furthermore, a distinct lattice spacing of 0.28 nm is observed (Figure f), attributed to the (002) plane of MoN (PDF#89‐5024), which confirm the formation of MoN nanoparticles. The interface exists between Ni and MoN nanoparticles in the heterostructures might lead to higher intrinsic catalytic activity and exposing more active sites . Besides, the elemental mapping was employed to further examine the composition of Ni/MoN@NCNT/CC.…”

Unveiling the Origin of the High Catalytic Activity of Ultrathin 1T/2H MoSe2 Nanosheets for the Hydrogen Evolution Reaction: A Combined Experimental and Theoretical Study

“…In recent years, there has been an ever-growing interest in the development of efficient, earth-abundant and inexpensive Pt-free electrocatalysts with long-term stability.O ft hese, molybdenum (Mo)-based compounds including Mo 2 C, [17][18][19] MoS 2 [20,21] and MoSe 2 [22,23] nanostructured materials have demonstrated remarkable HER performance [24,25] and have proven to be alternatives for Pt-based electrocatalysiso ft he HER. In particular, MoSe 2 represents ap romising non-noble-metalbased electrocatalyst and has one of the best-known HER performance in media.…”