In Situ Fabrication of a Nickel/Molybdenum Carbide-Anchored N-Doped Graphene/CNT Hybrid: An Efficient (Pre)catalyst for OER and HER

Abstract

Despite the recent promise of transition metal carbides as nonprecious catalysts for the hydrogen evolution reaction (HER), their extension to the oxygen evolution reaction (OER) to achieve the goal of overall water splitting remains a significant challenge. Herein, a new Ni/Mo x C (MoC, Mo2C) nanoparticle-supported N-doped graphene/carbon nanotube hybrid (NC) catalyst is developed via a facile, one-step integrated strategy, which can catalyze both the HER and OER in an efficient and robust manner. The catalyst affords low overpotentials of 162 and 328 mV to achieve a current density of 10 mA/cm2 for HER and OER, respectively, in alkaline medium, which either compares favorably or exceeds most of the Mo-based catalysts documented in the literature. It is believed that there is an electronic synergistic effect among Mo x C, Ni, and NC, wherein a tandem electron transfer process (Ni → Mo x C → NC) may be responsible for promoting the HER as well as OER activity. This work opens a new avenue toward the development of multicomponent, highly efficient but inexpensive electrocatalysts for overall water splitting.

RuNi Nanoparticles Embedded in N‐Doped Carbon Nanofibers as a Robust Bifunctional Catalyst for Efficient Overall Water Splitting

“…[40,41] The signals of Ni 3+ species appear clearly in the XPS spectrum of the post-OER sample, which is known to be highly active for OER. [59] Above results suggest that both Ru and Ni with high oxidation states are formed in the Ru 1 Ni 1 -NCNFs after OER test, which are conducive to the enhanced OER activity. By observing the sample after HER test in acidic media, it is found that the signal of Ni 0 almost disappears, whereas the majority of surface Ni in Ru 1 Ni 1 -NCNFs is oxidized with a +2 oxidation state, which is consistent with the previous results of EDX and XRD.…”

Ni‐Activated Transition Metal Carbides for Efficient Hydrogen Evolution in Acidic and Alkaline Solutions

“…[ 29,30 ] In its Ni 2p XPS spectrum (Figure 2c), the peak at 853.0 eV corresponds to the state of NiC, while no NiV bond was found in XPS analysis, illustrating that the V atoms have no interaction with Ni. [ 31,32 ] In its V 2p XPS spectrum (Figure 2d), four fitted V 2p peaks are located at 513.2, 515.6, 520.4, and 522.9 eV. They correspond to VC 2p 3/2 , VO 2p 3/2 , VC 2p 1/2 , and VO 2p 1/2 from the VC composition of VC, respectively.…”

“…They correspond to VC 2p 3/2 , VO 2p 3/2 , VC 2p 1/2 , and VO 2p 1/2 from the VC composition of VC, respectively. [ 29,32,33 ] As control experiments, the XPS spectra of V 2p and O 1s of the Ni‐GF/V 2 O 3 catalyst were also recorded (Figure S4, Supporting Information). The binding energy of the V 2p 3/2 in the Ni‐GF/VC catalyst is higher, when compared to that in the Ni‐GF/V 2 O 3 catalyst.…”

Ni-Based Composites from Chitosan Biopolymer a One-Step Synthesis for Oxygen Evolution Reaction

“…Additionally, the direct role of Mo x C should be considered. The synergistic effect between molybdenum carbide and Ni has also been observed before [13,19]. The Mo x C/Ni heterostructures contributes to the formation of in situ NiOOH/NiO(OH) 2 and molybdenum species during the anodic process, increasing the active sites exposed on the composites and promoting the OER performance.…”

“…Among them, Ni-containing materials, such as nickel oxides, nickel hydroxides, and nickel-metal alloys have been given special attention because of their abundance and their good water oxidation potential [3,[11][12][13][14]16,17]. Furthermore, some reports have shown that coupling molybdenum carbide with Ni significantly improves the OER performance [13,18,19]. For example, Ni 2.0 Mo 0.26 @N-carbon nanostructures have shown excellent OER electrocatalytic performances which are mainly attributed to the synergistic effect between γ-MoC and Ni heterostructures [13].…”